Managing Cover Crops Profitably - Valley Crops Home

$19.00 

Managing Cover Crops Profitably 

SECOND EDITION 

Farmers across the U.S. are using cover crops to smother weeds, deter pests and 

slow erosion.They find that cover crops help them cut costs and boost profits 

while improving their soil and protecting natural resources. 

This book distills findings from published studies and on-farm experience into 

a user-friendly reference tool for farmers and agricultural educators.You will find 

detailed information on how to select cover crops to fit your farm, and how to manage 

them to reap multiple benefits. 

Here is what the experts say. . . 

“If you’re like most farmers, you probably think you’re too busy for cover crops. 

My advice: Just do it. Discover how cover crops can hold and improve your soil 

and how they can suppress weeds, deter pests and take up excess nutrients. Feel the 

satisfaction of beautiful green fields in fall when everything else is dead, and the soil 

is bare and vulnerable. Cover crops make a big difference on my farm.They can do 

the same for you.” 

Richard De Wilde, vegetable grower, Viroqua, Wis. 

“Nowhere else can farmers and growers get the important detailed information they 

need to make their own decisions on integrating cover crops into crop rotations. 

Don’t forget to read the sidebars, which contain farmer experiences with cover 

crops.This really is a one-of-a-kind resource.” 

Noah Ranells, extension associate, North Carolina State University, 

Department of Crop Science 

“This book will be a great resource for farmers, educators, researchers and anyone 

who wants basic information and good ideas for how to use cover crops. I am particularly 

impressed with the way information is supported by personal experiences of 

farmers and researchers.” 

John R.Teasdale, research scientist, USDA-ARS, Beltsville, Md. 

Managing Cover Crops Profitably SECOND EDITION 

Managing Cover 

Crops Profitably SECOND 

EDITION 

SUSTAINABLE 

AGRICULTURE 

NETWORK 

THE NATIONAL OUTREACH ARM OF USDA-SARE 

HANDBOOK 

SERIES 

BOOK 3 

SUSTAINABLE 

AGRICULTURE 

NETWORK 


A publication of the Sustainable 

Agriculture Network with funding by the 

Sustainable Agriculture Research and 

Education program of the CSREES, 

U.S. Department of Agriculture 

ISBN 1-888626-04-6 

9 781888 626049 

Sustainable 

Agriculture Network

Agricultural Research Service, USDA 

USDA Plant Hardiness Zone Map 

AVERAGE ANNUAL MINIMUM TEMPERATURE 

Temperature (˚C) Zone Temperature (˚F) 

-45.6 and Below 1 Below -50 

-42.8 to -45.5 2a -45 to -50 

-40.0 to -42.7 2b -40 to -45 

-37.3 to -40.0 3a -35 to -40 

-34.5 to -37.2 3b -30 to -35 

-31.7 to -34.4 4a -25 to -30 

-28.9 to -31.6 4b -20 to -25 

-26.2 to -28.8 5a -15 to -20 

-23.4 to -26.1 5b -10 to -15 

-20.6 to -23.3 6a -5 to -10 

-17.8 to -20.5 6b 0 to -5 

-15.0 to -17.7 7a 5 to 0 

-12.3 to -15.0 7b 10 to 5 

-9.5 to -12.2 8a 15 to 10 

-6.7 to -9.4 8b 20 to 15 

-3.9 to -6.6 9a 25 to 20 

-1.2 to -3.8 9b 30 to 25 

1.6 to -1.1 10a 35 to 30 

4.4 to 1.7 10b 40 to 35 

4.5 and Above 11 40 and Above 

Source: Bailey, 1994 

Ecoregions of the United States 

DIVISIONS 

The areas within each Division 

are Provinces. 

1. Tundra 

2. Subarctic 

3. Warm Continental 

4. Hot Continental 

5. Subtropical 

6. Marine 

7. Prairie 

8. Mediterranean 

9. Tropical/Subtropical Steppe 

10.Tropical/Subtropical Desert 

11. Temperate Steppe 

12.Temperate Desert 

13.Savanna 

14.Rainforest 

Mountains with Altitudinal 

Zonation 

Source: R.G. Bailey (see p. 162).

SUSTAINABLE 

AGRICULTURE 

NETWORK 


HANDBOOK 

SERIES 

BOOK 3 

Managing Cover 

Crops Profitably 


A publication of the 

Sustainable Agriculture Network 

with funding by the 

Sustainable Agriculture Research and 

Education Program of CSREES, 

U.S. Department of Agriculture 


National Agricultural Library 

Beltsville, MD 20705-2351

Copyright This book © was 1998 published by the Sustainable by the Sustainable Agriculture Agriculture Network, 

with Network funding (SAN). from SAN the is Sustainable the national Agriculture outreach Research arm of and the 

Education Sustainable (SARE) Agriculture program Research of the and Cooperative Education State (SARE) Research program, 

which and is Extension a competitive Service grants (CSREES),U.S.Department program at USDA. SARE of 

Education 

Agriculture. provides funding Reprinted for research in 2000. and education projects that promote 

agricultural systems that are profitable, environmentally 

SAN, sound the and national enhance outreach the viability partner of communities of the USDA nationwide. SARE program, 

is a consortium of individuals, universities and government, 

SAN is business a consortium and nonprofit of individuals,university organizations and dedicated government, to the 

exchange business of and information nonprofit on organizations sustainable agricultural dedicated systems. to the 

exchange of information on sustainable agriculture systems. 

For SAN more operates information under Cooperative about the Agreements Sustainable between Agriculture the 

Network, Cooperative or about State Research, other SAN Education, publications, and contact: Extension Service, 

USDA, Andy the Clark University of Maryland and the University of 

Vermont SAN Coordinator 

develop and disseminate information about sustainable 

c/o AFSIC, agriculture. Room 304 See www.sare.org for information about 

SARE National grant Agricultural opportunities Library and SAN publications. 

10301 Baltimore Avenue 

For Beltsville, more information MD 20705-2351 about the Sustainable Agriculture 

Network, PH: 301-504-6425 or about other SAN publications, contact: 

Andy FAX: Clark 301-504-6409 

SAN san@nal.usda.gov 

Coordinator 

10300 www.sare.org Baltimore Ave., Bldg. 046 

Beltsville, MD 20705-2350 

SARE (301) is 504-5236; a competitive (301) 504-5207 grants program. (fax) It provides funding for 

research san_assoc@sare.org and education projects that promote agricultural 

systems that are profitable, environmentally sound and 

enhance To order the copies viability of this of rural book, communities ($19 plus nationwide. $5.95 s/h) go to 

www.sare.org/WebStore, call (301) 374-9696 or e-mail 

For sanpubs@sare.org. 

more information about the SARE program and SARE 

grants, contact: 

Material Office for of Sustainable this book and Agriculture its covers Programs was researched, written, 

illustrated, U.S. Department edited and of Agriculture produced for SAN. The book concept, 

format 1400 and Independence selection of Ave., featured S.W., farmers Stop 2223 and content reviewers 

Washington, were developed D.C. 20250-2223 under the auspices of SAN. 

Material For other for SAN this titles, book see and pp. its 198-199. covers was researched written, 

illustrated,edited and produced for the Sustainable Agriculture 

Network.The book concept, format, and selection of featured 

farmers and content reviewers were developed under the 

auspices of the Sustainable Agriculture Network. 

To order copies of this book, send a check or purchase order 

for $19 plus $3.95 shipping and handling to: 

Sustainable Agriculture Publications 

Hills Building, Room 10 

University of Vermont 

Burlington,VT 05405-0082 

Library of Congress Cataloguing-in-Publication Data 

Managing cover crops profitably.—2nd ed. 

p. cm.–(Sustainable Agriculture Network handbook series 

bk. 3) 

Includes bibliographical references (p. ) and index. 

ISBN 1-888626-04-6 (pbk) 

1. Cover crops—United States—Handbooks, manuals, etc. 

I. Sustainable Agriculture Network. II. Series. 

SB284.3.U6M36 1998 

631.5’82—dc2l 98-9887 

CIP 

2 4 6 8 9 7 5 3 1 

Printed in the United States of America on recycled paper. 

Every effort has been made to make this book as complete and 

as accurate as possible and to educate the reader.This text is 

only a guide,however,and should be used in conjunction with 

other information sources on crop, weed and farm management. 

No single cover crop strategy will be appropriate and 

effective for all conditions. The editor/authors and publisher 

disclaim any liability,loss,or risk,personal or otherwise,which 

is incurred as a consequence, directly or indirectly, of the use 

and application of any of the contents of this book. 

Mention, visual representation or inferred reference of a product, 

service, manufacturer or organization in this publication 

does not imply endorsement by the USDA, the SARE program 

or the authors.Exclusion does not imply a negative evaluation. 

Graphic design, interior layout and cover design: Diane Buric. 

Interior illustrations by: 1. Marianne Sarrantonio (reprinted 

with permission from the Northeast Cover Crop Handbook. 

1994. Rodale Institute. Emmaus, PA); and 2. Elayne Sears. 

Copy Editing:Valerie Berton and Andy Clark. Indexing: Nancy 

Hopkins. Printing: Jarboe Printing, Washington, D.C.. Cover 

photos by Tom Gettings; orchard photo by Chuck Ingels, Univ. 

of Calif. Extension. 

This book was written by Greg Bowman, Christopher 

Shirley and Craig Cramer, of CMR Editorial Services, for 

the Sustainable Agriculture Network. 

Call 802-656-0484 to order by credit card. For first book sent 

outside of N. America, please add $6. Add $2.50 for each 

additional book. Please include your mailing address and 

telephone number. 

The Sustainable Agriculture Network Handbook Series previous 

titles include Book 1: Managing Cover Crops Profitably 

(1st Edition), edited by the staff of the Rodale Institute; and 

Book 2: Steel in the Field: A Farmer’s Guide to Weed 

Management Tools,1997, edited by Greg Bowman.

ACKNOWLEDGMENTS 

This book represents a true cooperative 

effort. Most writing and research was by 

Christopher Shirley, Greg Bowman and 

Craig Cramer, formerly writers/editors for the 

New Farm Magazine. Their experience writing 

for the agricultural community shows in their 

ability to incorporate a vast amount of research 

data and farmer experiences into this publication. 

Contributors Marianne Sarrantonio, University of 

Maine, Orono, ME, Sharad Phatak, University of 

Georgia, and Andy Clark, Coordinator of the 

Sustainable Agriculture Network (SAN) each 

wrote sections of the book. Robert Myers, 

Wayne Reeves, Seth Dabney and 

Chuck Ingels contributed to 

Appendix B, Up-and-Coming 

Cover Crops. 

Farmers played a major 

role in developing the 

book, detailing their 

cropping systems and 

the management of 

cover crops on their 

farms. Some were contacted 

repeatedly for 

further clarification, and 

many also reviewed sections 

of the manuscript. 

The value of the contributions 

by farmers using cover 

crops in the field cannot be underestimated. 

They generously gave of 

their time to provide true ground-testing and 

reality-checking to strenthen this publication. 

A volunteer editorial board consisted of faculty 

and researchers from around the country: Rob 

Myers, Jefferson Institute,Columbia, Mo., formerly 

director of SARE; Fred Magdoff, Northeast Region 

SARE, University of Vermont; Seth Dabney, USDA- 

ARS Soil Sedimentation Lab;Wayne Reeves, USDA- 

ARS National Soil Dynamics Lab; Marianne 

Sarrantonio, University of Maine; Walter Goldstein 

and Jim Stute, Michael Fields Agricultural Institute, 

East Troy, Wis.; Richard Dick, Oregon State 

University; Jim Sims, Emeritus Professor, Montana 

State University; Chuck Ingels, University 

of California Extension Service. Andy Clark, 

Coordinator of the Sustainable Agriculture 

Network, oversaw the project and coordinated 

the efforts of the writers, the designer and the 

editorial board. 

The complete manuscript was reviewed at least 

twice by each member of the editorial board.It was 

also reviewed by Mark Davis, Delaware State 

University;John Luna,Oregon State University; 

Steve Diver, Appropriate Technology 

Transfer for Rural Areas (ATTRA), 

Fayetteville, Ark.; John and 

Lorraine Merrill, Stuart Farm, 

Stratham,N.H.;John Teasdale, 

USDA-ARS, Beltsville, Md.; 

Phil Bauer, USDA-ARS, 

Florence, S.C.; Morris 

Decker,Professor Emeritus, 

University of Maryland; 

Noah Ranells, North 

Carolina State University; 

and Valerie Berton, SARE 

communications specialist. 

Individual chapters of 

Managing Cover Crops 

Profitably, 2nd Edition were 

reviewed by cover crop experts 

from the farm and research 

communities.These farmers and scientists are 

too numerous to mention here, but their contributions 

were invaluable to this effort. 

In preparation for the second edition, the first 

edition was critically reviewed by Morris Decker, 

Professor Emeritus, University of Maryland; Zane 

Helsel, Rutgers University; and Andy Clark, SAN. 

Fred Magdoff, who was the driving force behind 

the first edition, participated in planning and 

reviewing throughout the process. 

BERSEEM CLOVER, an annual legume, produces abundant vegetation with multiple cuttings. 

ACKNOWLEDGMENTS 3

The first edition, written in 1991 by Mike 

Brusko at Rodale Institute, was used liberally in 

the development and writing of this second 

edition. 

Mary Gold and Abiola Adeyemi, from the 

Alternative Farming Systems Information Center 

at the National Agricultural Library,provided comprehensive 

literature searching and facilitated the 

duplication and lending of cover crop literature 

to the writers. Abiola Adeyemi also compiled 

parts of the Appendices and provided 

clerical support,particularly during 

the reviews of the book. 

Consulted repeatedly for 

guidance and information 

were reviewers or authors 

Seth Dabney, Sharad Phatak, 

Marianne Sarrantonio, Jim Sims, 

John Teasdale, Mary V. Gold 

(National Agricultural Library, 

Beltsville, Md.), Aref Abdul-Baki 

(USDA/ARS, Beltsville, Md.) and 

Robert Bugg (University of California, 

Davis, Calif.). 

The USDA Sustainable Agriculture 

Research and Education (SARE) program 

funded the project as part of its 

support of the Sustainable Agriculture Network 

(SAN). SAN is the communications and outreach 

arm of the SARE program. Other SARE support 

came in the form of extensive planning, design, 

writing and editing by SARE communications 

specialist Valerie Berton, College Park, Md. SAN 

publications committee chair Beth Holtzman, 

Burlington,Vt., contributed publication oversight, 

contract management and overall good sense 

about publishing sustainable agriculture information. 

Other members of the SAN 

Management Committee commented on 

early plans for the book, helped develop 

budgets, and were consulted on other 

aspects of the project as needed. 

As SAN Coordinator, I heartily thank all 

members of the sustainable agriculture 

community for their cooperation in providing 

information that will strenthen our agriculture 

for future generations. Such 

cooperation is truly the hallmark of the 

sustainable agriculture movement. 

Andy Clark, Coordinator 


Beltsville, Md. 

May, 1998 

BARLEY, a cool season grain, controls erosion and weeds in dry years and on light soils. 

4 MANAGING COVER CROPS PROFITABLY

FOREWORD 

Cover crops slow erosion, improve soil, 

smother weeds, enhance nutrient and 

moisture availability, help control many 

pests and bring a host of other benefits to your 

farm. At the same time, they can reduce costs, 

increase profits and even create new sources of 

income.You’ll reap dividends on your cover crop 

investments for years,because their benefits accumulate 

over the long term. 

Cover crops can make you a better neighbor, 

too. They prevent nutrient leaching and runoff, 

and reduce or eliminate the off-site impacts of 

herbicides and pesticides. 

There is a cover crop to fit just about every 

farming situation.The purpose of this book is to 

help you find which ones are right for you. 

Since the Sustainable Agriculture Network 

(SAN) published Managing Cover Crops 

Profitably in 1992, more and more farmers have 

tried cover crops and are researching their use in 

farming systems. Other research by university 

and government scientists, agricultural professionals 

and numerous farm organizations has 

contributed more information about how cover 

crops can enhance traditional cropping systems. 

This book distills published and unpublished 

cover crop experiences into a reader-friendly 

reference tool for use by farmers and agricultural 

professionals. Our writers reviewed published 

literature in scientific journals and talked with 

farmers and researchers using cover crops. The 

dedicated help of a knowledgeable editorial board 

and reviewers throughout the country rounded 

out the book. 

A publication of this scope cannot possibly 

describe all the cover crops currently in use.We 

have selected the most proven crops with the 

widest possible application in the continental 

United States. Because of space and time limitations, 

several very promising species were omitted 

or not given complete coverage. Some of 

these are mentioned in Appendix B, Up-and- 

Coming Cover Crops (p.158).Many other species 

with great potential as cover crops in particular 

climates or cropping systems are accessible 

through publications and cover crop experts listed 

in the appendices. 

Many of the proven species described in the 

book may be more familiar as forage or cash 

crops.These crops have been adapted for use as 

cover crops, which, strictly speaking, are not 

harvested. Our primary intent in this book is to 

describe the use of these crops as cover crops. 

Because economics plays a major role in deciding 

which crops farmers include in their rotations,we 

do mention some important alternative uses that 

make growing cover crops even more rewarding. 

If you plant one of these cover crops and want 

the option to harvest it as a cash crop, consult 

other resources for more complete information. 

We have tried to include enough information 

for you to select and use cover crops appropriate 

to your operation.We recommend that you define 

your reasons for growing a cover crop—the section, 

Selecting the Best Cover Crops for Your 

Farm (p. 30) can help with this—and take as 

much care in selecting and managing cover crops 

as you would a cash crop. 

Regional and site-specific factors can complicate 

cover crop management. No book can adequately 

address all the variables that make up a 

crop production system. Before planting a cover 

crop,learn as much as you can from this book and 

talk to others who are experienced with that 

cover crop. Consult state and local resources for 

specific information about adaptation and management 

of a cover crop in your area. See also 

Recommended Resources (p. 162). 

We hope that this updated and greatly expanded 

edition of Managing Cover Crops Profitably 

will lead to the successful use of cover crops on 

a wider scale as we continue to increase the 

sustainability of our farming systems. 

Andy Clark, Coordinator 

Sustainable Agriculture Network (SAN) 

May, 1998 

FOREWORD 5

MANAGING COVER CROPS PROFITABLY 


Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . 3 

Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 

How to Use . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 

Benefits of Cover Crops . . . . . . . . . . . . . . . . . . 9 

Selecting the Best Cover Crops 

for Your Farm . . . . . . . . . . . . . . . . . . . . . . . . 12 

Building Soil Fertility and Tilth 

with Cover Crops . . . . . . . . . . . . . . . . . . . . 16 

• Cover Crops Can Stabilize Your Soil . . . 19 

• How Much N . . . . . . . . . . . . . . . . . . . . . . 22 

Managing Pests with Cover Crops . . . . . . . . . 25 

• Georgia Cotton, Peanut Farmers 

Use Cover Crops to Control Pests . . . . . . 26 

• Select Covers that Balance Pests, 

Problems of Farm . . . . . . . . . . . . . . . . . . . 30 

Crop Rotations with Cover Crops . . . . . . . . . 34 

• Full-Year Covers Tackle Tough Weeds . . . 38 

Overview of Charts . . . . . . . . . . . . . . . . . . . . . 43 

Chart 1:Top Regional Cover Crop Species . . . 47 

Chart 2: Performance and Roles . . . . . . . . . . . 48 

Chart 3A: Cultural Traits. . . . . . . . . . . . . . . . . . 50 

Chart 3B: Planting . . . . . . . . . . . . . . . . . . . . . . 51 

Chart 4A: Potential Advantages . . . . . . . . . . . . 52 

Chart 4B: Potential Disadvantages. . . . . . . . . . 53 

Cover Crop Species 

Overview of Nonlegume Cover Crops . . . 54 

Annual Ryegrass. . . . . . . . . . . . . . . . . . . . . . . . 55 

Barley . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58 

Oats . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62 

Cereal Rye . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65 

• Rye Smothers Weeds Before Soybeans . . 67 

Winter wheat. . . . . . . . . . . . . . . . . . . . . . . . . . 72 

• Wheat Boosts Income and 

Soil Protection . . . . . . . . . . . . . . . . . . . . . . 74 

• Wheat Offers High-Volume 

Weed Control Too . . . . . . . . . . . . . . . . . . . 75 

Buckwheat . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 

Sorghum Sudangrass . . . . . . . . . . . . . . . . . . . . 80 

• Summer Covers Relieve Compaction . . 84 

Overview of Legume Cover Crops . . . . . . 85 

Grass/Legume Mixtures Expand 

Possibilities . . . . . . . . . . . . . . . . . . . . . . . . 86 

Berseem Clover . . . . . . . . . . . . . . . . . . . . . . . . 87 

• Crimson-Berseem Clover Combo 

Works as Corn Underseeding . . . . . . . . . 89 

• Nodulation: Match Inoculant to 

Maximize N . . . . . . . . . . . . . . . . . . . . . . . . 92 

Cowpeas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 

• Cowpeas Provide Elegant Solution 

to Awkward Niche . . . . . . . . . . . . . . . . . . 98 

Crimson Clover . . . . . . . . . . . . . . . . . . . . . . . 100 

Field Peas . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105 

• Peas Do Double Duty 

for Kansas Farmer . . . . . . . . . . . . . . . . . 110 

Hairy Vetch. . . . . . . . . . . . . . . . . . . . . . . . . . . 112 

• Vetch Beats Plastic . . . . . . . . . . . . . . . . . 118 

Medics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 

• Jess Counts on GEORGE for N and 

Organic Matter. . . . . . . . . . . . . . . . . . . . 121 

• Southern Spotted Bur Medic Offers 

Reseeding Persistence. . . . . . . . . . . . . . . 122 

Red Clover . . . . . . . . . . . . . . . . . . . . . . . . . . . 127 

Subterranean Clover . . . . . . . . . . . . . . . . . . . 132 

Sweetclover . . . . . . . . . . . . . . . . . . . . . . . . . . 139 

• Sweetclover: Good Grazing, 

Great Green Manure. . . . . . . . . . . . . . . 142 

White Clover . . . . . . . . . . . . . . . . . . . . . . . . . 147 

Woollypod Vetch . . . . . . . . . . . . . . . . . . . . . . 151 

Appendices 

A.Testing Cover Crops on Your Farm . . . . . . 156 

B. Up-and-Coming Cover Crops. . . . . . . . . . . 158 

C. Recommended Resources. . . . . . . . . . . . . 162 

D. Seed Suppliers . . . . . . . . . . . . . . . . . . . . . . 166 

E. Farming Organizations with 

Cover Crop Expertise . . . . . . . . . . . . . . . . 170 

F. Regional Experts. . . . . . . . . . . . . . . . . . . . . 173 

G. Citations Bibliography . . . . . . . . . . . . . . . . 180 

H. Resources from the Sustainable 

Agriculture Network . . . . . . . . . . . . . . . . . 198 

I. Reader Response Form. . . . . . . . . . . . . . . . 200 

Index . . . . . . . . . . . . . . . . . . . . . . . . . .201 


HOW TO USE THIS BOOK 

Think of this book as a tool chest, not a 

cookbook.You won’t find the one simple 

recipe to meet your farming goals.You will 

find the tools to select and manage the best cover 

crops for the unique needs of your farm. 

In this tool chest you will find helpful maps and 

charts, detailed narratives about individual cover 

crop species, chapters about specific aspects of 

cover cropping and extensive appendices that 

will lead you to even more information. 

The entire text of Managing Cover Crops 

Profitably, 2nd Edition is available on CD-ROM. 

The electronic version is a great resource for agricultural 

educators and computer-savvy producers 

because it allows users to search for crops with 

one click of the mouse—and download sections 

into new files for presentations and fact sheets. 

To order, see p. 199. 

1. Start with Top Regional Cover Crop Species 

(p. 47). This chart will help you narrow your 

search by listing the benefits you can expect from 

the top cover crops adapted to your region.You’ll 

discover which are the best nitrogen (N) sources, 

soil builders, erosion fighters, subsoil looseners, 

weed fighters and pest fighters. 

heart of the book, the chapters on each cover 

crop. The chapters offer even more practical 

descriptions of how to plant, manage, kill and 

make the best use of each species. 

Don’t overlook Up-and-Coming Cover Crops 

(p. 158) that briefly describes promising but 

lesser known cover crops. One of them may be 

right for your farm. 

3. With some particular cover crops in mind, 

step back and look at the big picture of how you 

can fit cover crops into your farming operations. 

Sit down with a highlighter and explore these 

chapters: 

• Benefits of Cover Crops (p. 9) explains 

important cover crop roles such as reducing 

costs, improving soil and managing pests. 

• Selecting the Best Cover Crops (p. 12) helps 

you evaluate your operation’s needs and niches 

(seasonal, cash-crop related, and profit potential). 

Several examples show how to fit crops to 

detailed situations. 

• Building Soil Fertility and Tilth (p. 16) 

shows how cover crops add organic matter and 

greater productivity to the biological, chemical 

and physical components of soil. 

2. Next, find out more about the performance 

and management of the cover crops that look like 

good candidates for your farm. You’ll find two 

streams of information: 

• Charts quickly provide you with details to 

help you compare cover crops. Performance and 

Roles (p.48) lists ranges for N and dry matter production 

and ranks each cover crop’s potential for 

providing 11 benefits. Cultural Traits (p. 50) and 

Planting (p. 51) explains the growth, environmental 

tolerances, seeding preferences and establishment 

costs for each crop. 

• Narratives. The Table of Contents (p. 6) 

and the page numbers accompanying each 

species in Charts 2, 3 and 4 direct you to the 

SORGHUM-SUDANGRASS is a tall, warm-season grass that stifles weeds and decomposes to build soil organic matter. 

HOW TO USE THIS BOOK 7

• Managing Pests with 

Cover Crops (p. 25) 

explores how cover 

crops change field 

environments to 

protect cash crops 

from insects, disease, 

weeds and 

nematodes. 

• Crop Rotations 

(p. 34) explains how to 

integrate cover crops and 

cash crops in sequence from 

year to year for optimum productivity 

from on-farm resources. 

• Citations Bibliography (p. 180) lists many of 

the publications and specialists cited in the book. 

Citations within the book are numbered in parentheses. 

Refer to the numbered citation in the bibliography 

if you want to dig deeper into a topic. 

• Climatic Zone Maps inside the front and 

back covers help you understand differences in 

cover crop performance from location to location. 

You may find that some cover crops have 

performed well in tests far from where you farm, 

but under comparable climatic conditions. 

The USDA Plant Hardiness Zone Map 

(inside front cover) shows whether a crop will 

survive the average winter in your area.We refer 

to the USDA hardiness zones throughout the 

book. 

The U.S. Forest Service map, Ecoregions of 

the United States (inside back cover), served 

in part as the basis for the adaptation maps included 

at the beginning of each cover crop chapter. 

This ecosystem map, while designed to classify 

forest growth, shows localized climate differences, 

such as rainfall and elevation, within a 

region. (See Bailey in Recommended Resources, 

p. 162). 

4. Now that you’ve tried out most of the tools, 

revisit the charts and narratives to zero in on the 

cover crops you want to 

try. The Appendices 

include information 

to help you run reliable 

on-farm cover 

crop comparison 

trials. You’ll also 

find contact information 

for cover 

crop experts in your 

region, seed suppliers 

and inoculant providers, 

references to books and other 

academic papers cited in this book 

and World Wide Web resources with more 

cover crop information. 

5. Finally, share your cover crop plans with farmers 

in your area who have experience with cover 

crops. Your local Extension staff, regional IPM 

specialist or a sustainable farming group in your 

area may be able to provide contacts.Be sure to tap 

local wisdom.You can find out the cover crop practices 

that have worked traditionally, and the new 

wrinkles or crops that innovative practitioners 

have discovered. 

Abbreviations used in this book 

A = acre or acres 

bu. = bushel or bushels 

DM = dry matter, or dry weight of plant material 

F = (degrees) Fahrenheit 

in. = inch or inches 

K = potassium 

lb. = pound or pounds 

N = nitrogen 

OM = organic matter 

P = phosphorus 

p. = page 

pp. = pages 

T = ton or tons 

> = progression to another crop 

/ = a mixture of crops growing together 

Cultivars of SUBTERRANEAN CLOVER, a low-growing, reseeding annual legume, are adapted to many climates. 


BENEFITS OF COVER CROPS 

Cover crops can boost your profits the first 

year you plant them. They can improve 

your bottom line even more over the years 

as their soil-improving effects accumulate. Other 

benefits—reducing pollution,erosion and weed and 

insect pressure—may be difficult to quantify or may 

not appear in your financial statements. Identifying 

these benefits, however, can help you make sound, 

long-term decisions for your whole farm. 

What follows are some important ways to evaluate 

the economic and ecological aspects of 

cover crops. These significant benefits (detailed 

below) vary by location and season, but at least 

two or three usually occur with any cover crop. 

Consult local farming groups and agencies with 

cover crop experience to figure more precise 

crop budgets. 

• Cut fertilizer costs 

• Reduce the need for herbicides and other 

pesticides 

• Improve yields by enhancing soil health 

• Prevent soil erosion 

• Conserve soil moisture 

• Protect water quality 

• Help safeguard personal health 

Evaluate a cover crop’s impact as you would 

any other crop, balancing costs against returns in 

all forms. Don’t limit your calculations, however, 

to the target cover crop benefit. A cover often 

has several benefits. Many cover crops offer 

harvest possibilities as forage, grazing or seed 

that work well in systems with multiple crop 

enterprises and livestock. 

SPELLING IT OUT 

Here’s a quick overview of benefits you can grow 

on your farm. Cover crops can: 

Cut fertilizer costs by contributing N to cash 

crops and by scavenging and mining soil nutrients. 

Legume cover crops convert nitrogen gas in 

the atmosphere into soil nitrogen that plants can 

use. See Nodulation: Match Inoculant to 

Maximize N (p. 92). Crops grown in fields after 

legumes can take up at least 30 to 60 percent of 

the N that the legume produced.You can reduce 

N fertilizer applications accordingly. For more 

information on nitrogen dynamics and how to calculate 

fertilizer reductions, see Building Soil 

Fertility and Tilth with Cover Crops (p. 16). 

The N value of legumes is the easiest cover 

crop benefit to evaluate, both agronomically 

and economically. This natural fertility input 

alone can justify cover crop use. 

• Hairy vetch boosted yield for no-till corn 

more than enough to cover its establishment 

costs, a three-year study in Maryland showed. 

Further, the vetch can reduce economic risk and 

usually will be more profitable than no-till corn 

after a winter wheat cover crop. The result 

held true even if corn were priced as low as $1.80 

per bushel, or N fertilizer was applied at the rate 

of 180 lb. N/A (136). 

• Medium red clover companion seeded with 

oats and hairy vetch had estimated fertilizer 

replacement value of 65 to 103 lb. N/A in a fouryear 

study in Wisconsin, based on a two year rotation 

of oats/legume > corn. Mean corn grain yield 

following these legumes was 163 bu./A for red 

clover and 167 bu./A for hairy vetch, compared 

with a no legume/no N fertilizer yield of 134 

bu./A (328). 

RED CLOVER is an annual or multi-year legume that improves topsoil. It is easily overseeded into standing crops 

or frostseeded into grains in early spring. 

BENEFITS OF COVER CROPS 9

• Austrian winter peas, hairy vetch and 

NITRO alfalfa can provide 80 to 100 percent of a 

subsequent potato crop’s nitrogen requirement, a 

study in the Pacific Northwest showed (322). 

• Fibrous-rooted cereal grains or grasses are 

particularly good at scavenging excess nutrients—especially 

N—left in the soil after cash crop 

harvest. Much of the N is 

held within the plants until 

they decompose. Fall-seeded 

grains or grasses can absorb 

up to 71 lb. N/A within three 

months of planting, a Maryland 

study showed (30). 

Addition of cover crops to 

corn>soybean and corn>peanut>cotton rotations 

and appropriate timing of fertilizer application 

usually reduce total N losses, without causing 

yield losses in subsequent crops, a USDA-ARS 

computer modeling study confirms (293). 

Reduce the Need for Herbicides 

Cover crops suppress weeds and reduce damage 

by diseases, insects and nematodes. 

Many cover crops effectively suppress weeds as: 

• A smother crop that outcompetes weeds for 

water and nutrients 

• Residue or growing leaf canopy that blocks 

light, alters the frequency of light waves and 

changes soil surface temperature 

• A source of root exudates or compounds that 

provide natural herbicidal effects 

Managing Pests with Cover Crops (p. 30) 

describes how cover crops can: 

• Host beneficial microbial life that discourages 

disease 

• Create an inhospitable soil environment for 

many soilborne diseases 

• Encourage beneficial insect predators and 

parasitoids that can reduce insect damage 

below economic thresholds 

• Produce compounds that reduce nematode 

pest populations 

• Encourage beneficial nematode species 

Using a rotation of malting barley>cover crop 

radish>sugar beets has successfully reduced sugar 

beet cyst nematodes to increase yield of sugar 

To estimate your potential 

N fertilizer savings from a 

cover crop, see the sidebar, 

How Much N (p. 22). 

beets in a Wyoming test. Using this brassica cover 

crop after malting barley or silage corn substituted 

profitably for chemical nematicides when 

nematode levels were moderate (184). 

A corn>rye>soybeans>wheat>hairy vetch rotation 

that has reduced pesticide costs is at least 

as profitable as conventional grain rotations 

without cover crops, an ongoing 

study in southeastern 

Pennsylvania shows (137). 

Fall-planted brassica cover 

crops coupled with mechanical 

cultivation help potato 

growers with a long growing 

season maintain marketable 

yield and reduce herbicide applications by 25 

percent or more, a study in the inland Pacific 

Northwest showed (322). 

Improve Yields by Enhancing Soil Health 

Cover crops improve soil by: 

• Speeding infiltration of excess surface water 

• Relieving compaction and improving structure 

of overtilled soil 

• Adding organic matter that encourages 

beneficial soil microbial life 

• Enhancing nutrient cycling 

Building Soil Fertility and Tilth with Cover 

Crops (p. 16) details the biological and chemical 

processes of how cover crops improve soil health 

and nutrient cycling. Leading soil-building crops 

include rye (residue adds organic matter and 

conserves moisture); sorghum-sudangrass (deep 

penetrating roots can break compaction); and 

ryegrass (stabilizes field roads,inter-row areas and 

borders when soil is wet). 

Prevent Soil Erosion 

Quick-growing cover crops hold soil in place, 

reduce crusting and protect against erosion due 

to wind and rain. The aboveground portion of 

covers also helps protect soil from the impact of 

raindrops. Long-term use of cover crops increases 

water infiltration and reduces runoff that can 

carry away soil. 

The key is to have enough stalk and leaf growth 

to guard against soil loss. Succulent legumes 


decompose quickly, especially in warm weather. 

Winter cereals and many brassicas have a better 

chance of overwintering in colder climates.These 

late-summer or fall-planted crops often put on significant 

growth even when temperatures drop 

into the 50s,and often are more winter-hardy than 

legumes (302). 

In a no-till cotton system, use of cover crops 

such as winter wheat, crimson clover and hairy 

vetch can reduce soil erosion while maintaining 

high cotton yields, a Mississippi study shows (21). 

Conserve Soil Moisture 

Residue from killed cover crops increases 

water infiltration and reduces evaporation, 

resulting in less moisture 

stress during drought. Lightly 

incorporated cover crops serve 

dual roles. They trap surface 

water and add organic matter to 

increase infiltration to the root 

zone. Especially effective at 

covering the soil surface are 

grass-type cover crops such as 

rye, wheat, and sorghum- 

Sudangrass hybrid. Some water-efficient 

legumes such as medic and 

INDIANHEAD lentils provide cover crop 

benefits in dryland areas while 

conserving more moisture than conventional 

bare fallow (316). 

Timely spring termination of a cover 

crop avoids the negative impact of 

opposite water conditions: excess 

residue holding in too much moisture 

for planting in wet years, or 

living plants drawing too much moisture from the 

soil in dry years. 

Protect Water Quality 

By slowing erosion and runoff, cover crops 

reduce nonpoint source pollution caused by 

sediments, nutrients and agricultural chemicals. 

By taking up excess soil nitrogen, cover crops 

prevent N leaching to groundwater. Cover crops 

also provide habitat for wildlife. 

A rye cover crop scavenged from 25 to 100 

percent of residual N from conventional and 

no-till Georgia corn fields, one study showed. Up 

to 180 lb. N/A had been applied. A barley 

cover crop removed 64 percent of soil nitrogen 

when applied N averaged 107 lb./A (177). 

Help Safeguard Personal Health 

By reducing reliance on agrichemicals 

for cash crop production, 

cover crops help protect the 

health of your family, neighbors 

and farm workers.They also help 

address community health and 

ecological concerns arising from 

nonpoint source pollution attributed 

to farming activities. 

Cumulative Benefits 

You can increase the range of benefits 

by increasing the diversity of cover 

crops grown, the frequency of use 

between cash crops and the length of 

time that cover crops are growing in 

the field. 

WINTER WHEAT grows well in fall, then provides forage and protects soil over winter. 

BENEFITS OF COVER CROPS 11

SELECTING THE BEST COVER CROPS FOR YOUR FARM 

by Marianne Sarrantonio 

Cover crops provide many benefits, 

but they’re not do-it-all “wonder crops.” 

To find a suitable cover crop or mix 

of covers: 

• Clarify your primary needs 

• Identify the best time and place for a cover 

crop in your system 

• Test a few options 

This book makes selection of cover crops a little 

easier by focusing on some proven ones. 

Thousands of species and varieties exist,however. 

The steps that follow can help you find crops that 

will work best with a minimum of risk and 

expense. 

1. Identify Your Problem or Use 

Review Benefits of Cover Crops (p. 9) to decide 

what you want most from a cover crop. This 

simplifies your search. 

Some common goals for covers are to: 

• Provide nitrogen 

• Add organic matter 

• Improve soil structure 

• Reduce soil erosion 

• Provide weed control 

• Manage nutrients 

• Furnish moisture-conserving mulch 

Having one or two secondary goals can narrow 

the hunt when comparable covers could satisfy a 

primary role. You might want habitat for beneficial 

organisms, better traction during harvest, 

faster drainage or another benefit. 

2. Identify the Niche 

Sometimes it’s obvious where and when to use a 

cover crop.You might want some nitrogen before 

a corn crop,or a perennial ground cover in a vineyard 

or orchard to reduce erosion or improve 

weed control. For some goals, such as building 

soil, it may be hard to decide where and when to 

schedule cover crops. 

Look at your rotation first. Make a timeline of 

18 to 24 monthly increments across a piece of 

paper.For each field,pencil in current or probable 

rotations, showing when you typically seed crops 

and when you harvest them. If possible, sketch in 

a rough graph showing average daily temperature 

during the timeline, and another for average rainfall.Add 

other key information, such as frost-free 

periods and times of heavy labor or equipment 

demand. 

Look for open periods in each field, open 

spaces on your farm or opportunities in your seasonal 

work schedule. Also consider ways to 

extend or overlap cropping windows. 

Here are examples of common niches in some 

systems, and some tips: 

Winter fallow niche. In many regions,seed winter 

covers at least six weeks before a hard frost. 

Winter cereals are an exception and can be planted 

a little later.If ground cover needs are minimal, 

plant rye until the frost period for successful overwintering, 

although N recycling will be limited. 

You might seed a cover right after harvesting a 

summer crop, when the weather is still mild. In 

cooler climates, consider extending the window 

by overseeding (some call this underseeding) a 

shade-tolerant cover before cash crop harvest. 

White clover, annual ryegrass, rye, hairy vetch, 

crimson clover, red clover and sweetclover tolerate 

some shading. 

If overseeding, irrigate immediately if possible, 

or seed just before a soaking rain. Species with 

small, round seeds, such as clovers, don’t need a 

lot of moisture to germinate and can work their 

way through tiny gaps in residue. 

If you want to harvest a cereal grain cover crop, 

interseeding a legume might increase disease 

risks due to lower air circulation or insect pest 

risk,so plan accordingly.Changing seeding rate or 

the rotation sequence may lessen this risk. 

To ensure adequate sunlight for the cover crop, 

overseed before full canopy closure of the primary 

crop (at last cultivation of field corn, for example) 

or a few weeks before the cash crop starts to die. 


Expect excessive field traffic around harvesttime 

Choose tough, low-growing covers such 

as grasses or clovers. Limit traffic or delay a field 

operation to allow for cover crop establishment. 

Another option could be a reseeding winter 

annual that dies back and drops seed each spring 

but reestablishes in fall. Subclovers reseed well 

in regions south of Hardiness Zone 6. Shorterseason 

crimson clovers—especially varieties with 

a high hard-seed percentage that germinate over 

an extended period—work well in the Southeast 

where moisture is sufficient. 

Summer fallow niche. Many vegetable rotations 

present cover crop opportunities—and 

challenges. When double cropping, you might 

have fields with a three- to eight-week summer 

fallow. Quick-growing summer 

annuals provide erosion control, 

weed management, organic matter 

and perhaps some N. 

Consider overseeding into a 

spring crop with buckwheat, 

millet or sorghum-Sudangrass, or 

a warm-season legume such as cowpeas. Or till 

out strips in the cover crop for planting a fall 

vegetable crop and control the remaining cover 

between the crop rows with mowing, partial 

cultivation or herbicide spraying. 

Small grain rotation niche. Companion seed a 

winter annual cover crop with a spring grain, 

or frost seed a cover into winter grains. Soil 

freezing and thawing pulls seed into the soil and 

helps germination. Another option if soil 

moisture isn’t a limiting factor in your region: 

broadcast a cover before the grain enters boot 

stage (when seedheads start elongating) later in 

spring. 

Full-year improved fallow niche. To rebuild 

fertility or organic matter over a longer period, 

perennials or biennials—or mixtures—require 

the least maintenance. Spring-seeded yellow 

blossom sweetclover flowers in summer of 

Year 2, has a deep taproot and gives plenty of 

aboveground biomass. Also consider perennial 

forages recommended for your area. 

Look for open periods 

in each field or open 

spaces on your farm. 

Properly managed, living mulches give many 

growers year-round erosion protection,weed control, 

nutrient cycling and even some nitrogen if 

they include a legume. Some tillage, mowing or 

herbicides can help manage the mulch (to keep it 

from using too much soil moisture, for example) 

before crops are strip-tilled into the cover or 

residue.White clover could be a good choice for 

sweet corn and tomatoes. Perennial ryegrass or 

other nonaggressive turfgrasses work for beans, 

tomatoes and other vegetables. 

Creating new niches. Have you honed a rotation 

that seems to have few open time slots Plant 

a cover in strips alternating with your annual vegetable, 

herb or field crop. Switch the strips the 

next year. Mow the strips periodically and blow 

the topgrowth onto adjoining 

cash crops as mulch. In a bed 

system, rotate out every third or 

fourth bed for a soil-building 

cover crop. 

Another option: Band a cover 

or some insect-attracting shrubs 

around fields or along hedgerows to suppress 

weeds or provide beneficial habitat where you 

can’t grow cash crops. 

3. Describe the Niche 

Refer to your timeline chart and ask questions 

such as: 

• How will I seed the cover 

• What’s the weather likely to be then 

• What will soil temperature and moisture 

conditions be like 

• How vigorous will other crops (or pests) be 

• Should the cover be low-growing and 

spreading, or tall and vigorous 

• What weather extremes and field traffic must 

it tolerate 

• Will it winterkill in my area 

• Should it winterkill, to meet my goals 

• What kind of regrowth can I expect 

• How do I kill it and plant into it 

• Will I have the time to make this work 

• What’s my contingency plan—and risks—if the 

crop doesn’t establish or doesn’t die on schedule 

• Do I have the needed equipment and labor 

SELECTING THE BEST COVER CROPS 13

4. Select the Best Cover Crop 

You have a goal and a niche. Now specify the 

traits a cover crop would need to work well. 

Example 1. A sloping orchard needs a ground 

cover to reduce erosion. You’d like it to contribute 

N and organic matter and attract beneficial 

organisms but not rodents,nematodes or 

other pests. The cover can’t use too much 

water or tie up nutrients at key periods. Too 

much N might stimulate excessive leaf growth or 

prevent hardening off before winter. Finally you 

want easy maintenance. 

The cover crop should: 

• be a perennial or reseeding annual 

• be low-growing, needing minimal management 

• use water efficiently 

• have a soil-improving root system 

• release some nutrients during the year, but not 

too much N 

• not harbor or attract pests 

For this orchard scenario, white clover is 

probably the best option north of Zone 8. A 

mixture of low-growing legumes or a legume and 

grass mix could also work. In warm regions, lowgrowing 

clovers such as strawberry clover and 

white clover work well together, although these 

species may attract pocket gophers. BLANDO 

brome and annual ryegrass are two quick-growing, 

reseeding grasses often suitable for orchard 

floors. One of these might fill the bill with a 

reseeding, winter annual legume such as crimson 

clover, rose clover, subclover, an annual vetch or 

an annual medic, depending on your climate. 

Example 2. A dairy lacks adequate storage in 

fall and winter for the manure it generates, 

which exceeds the nutrient needs for its silage 

corn and grass/legume hay rotation. 

The cover crop needs to: 

• establish effectively after (or tolerate) silage 

corn harvest 

• take up a lot of N and P in fall and hold it until 

spring 

For this dairy scenario, rye is often recommended. 

Other cereal grains or brassicas could 

work if planted early enough. 

Example 3. In a moderate rainfall region after 

small grain harvest in late summer, you want 

a soil-protecting winter cover that can supply 

N for no-till corn next spring. You want to kill 

the cover without herbicides. 

You need a legume that: 

• can be drilled in late summer and put on a lot 

of fall growth 

• will overwinter 

• will fix a lot of N 

• can be mow-killed shortly before (or after) 

corn planting 

• could provide some weed-controlling, 

moisture-conserving residue 

Hairy vetch works well in the Northeast, 

Midwest and parts of the mid-South. Mixing it 

with rye or another cereal improves its weedmanagement 

and moisture-conservation potential.Crimson 

clover may be an appropriate choice 

for the southeastern Piedmont. Austrian winter 

pea could be considered, alone or in a mix, in 

coastal plain environments. Where grain harvest 

occurs in late spring or early summer, LANA woollypod 

vetch might be a better choice. 

HAIRY VETCH is an winter annual legume that grows slowly in fall, then fixes a lot of N in spring. 


5. Settle for the Best Available Cover. . . 

It’s likely the “wonder crop” you want doesn’t 

exist. One or more species could come close, as 

the above examples indicate. Top Regional Cover 

Crop Species (p. 47) can provide a starting point. 

Check with regional experts. Keep in mind that 

you can mix two or more species. 

Example 4. After a spring broccoli crop, you 

need a weed-suppressing cover that adds N 

and organic matter, and perhaps mulch, into 

which you will no-till seed fall lettuce or spinach. 

You want a cover that: 

• is very versatile 

• grows fast in hot weather 

• can be overseeded into broccoli 

• germinates on the soil surface under dry 

conditions 

• fixes N 

• persists until you’re ready to kill it 

Here, a quick-growing, warm-season legume such 

as cowpeas may work, especially if you can irrigate 

to hasten establishment during dry conditions. 

6. . . .Or Build a Rotation Around 

Cover Crops. 

It’s hard to decide in advance every field’s crops, 

planting dates, fieldwork or management 

specifics. One alternative is to find out which 

cover crops provide the best results on your farm, 

then build a rotation around those covers. See 

Full-Year Covers Tackle Tough Weeds (p. 38). 

With this “reverse” strategy, you plan covers 

according to their optimum field timing, and then 

determine the best windows for cash crops. A 

cover crop’s strengths help you decide which 

cash crops would benefit the most. 

For now, however, you probably want to fit one 

or more cover crops into your existing rotations. 

The charts and narratives in this book can help 

you select some of the most suitable species for 

your farming system and objectives. See Crop 

Rotations with Cover Crops (p. 34) to get you 

thinking more. When you’ve narrowed your 

choices, refer to Appendix A, Testing Cover Crops 

on Your Farm (p. 156) for some straightforward 

tips on what to do next. 

Adapted from Northeast Cover Crop Handbook 

by Marianne Sarrantonio, Rodale Institute, 1994. 

WINTER (cereal) RYE is an annual grain that prevents soil and wind erosion. Its killed vegetation suppresses 

weeds for no-till planting. 

SELECTING THE BEST COVER CROPS 15

BUILDING SOIL FERTILITY AND TILTH 

WITH COVER CROPS 


Soil is an incredibly complex substance. It has 

physical and chemical properties that allow 

it to sustain living organisms—not just plant 

roots and earthworms,but hundreds of thousands 

of different insects, wormlike creatures and 

microorganisms. When these organisms are in 

balance, your soil cycles nutrients efficiently, 

stores water and drains the excess, and maintains 

an environment in which plants can thrive. 

To recognize that a soil can be healthy, one 

has only to think of the soil as a living entity. It 

breathes, it transports and transforms nutrients, it 

interacts with its environment, and it can even purify 

itself and improve over time. If you view soil as a 

dynamic part of your farming system, unsustainable 

crop management practices amount to soil neglect. 

That neglect could worsen as the soil sickens and 

loses its life functions one by one. 

Regardless of how healthy or alive your soil is 

right now, cover crops can play a vital role in 

ensuring that your soil provides a strong foundation 

for your farming system. While the most 

common reasons for including cover crops in 

a farming system may relate to the current 

season, the continued practice of cover cropping 

becomes an investment in building healthy soil 

over the long term. 

Cover crops improve soil in a number of ways. 

Protection against soil loss from erosion is perhaps 

the most obvious soil benefit of cover crops, 

but providing organic matter is a more long-term 

and equally important goal. Cover crops contribute 

indirectly to overall soil health by catching 

nutrients before they can leach out of the soil profile 

or by adding nitrogen to the soil.Their roots 

can even help unlock some nutrients, converting 

them to more available forms. Cover crops provide 

habitat or a food source for some important 

soil organisms, break up compacted layers in the 

soil and help dry out wet soils. 

EROSION PROTECTION 

Erosion of topsoil occurs on many farms, depriving 

fields of the most fertile portion that contains 

the highest percentage of organic matter and 

nutrients. Cover crops can play a major role in 

fighting soil erosion. 

A raindrop falling at high speed can dislodge 

soil particles and cause them to move as far as 6 

feet (28). Once a soil particle is loose, it is much 

more vulnerable to being carried away by 

running water. Any aboveground soil cover can 

take some of the punch out of a heavy rainfall 

simply by acting as a cushion for raindrops. 

A cover crop also can: 

• Slow the action of moving water just by 

creating an obstacle course of leaves, stems 

and roots through which the water must 

maneuver on its way downhill 

• Increase the soil’s ability to absorb and hold 

water, thereby preventing large quantities of 

water from moving across the soil surface 

• Help stabilize soil particles in the cover crop 

root system 

The reduction in soil erosion due to cover 

cropping will be roughly proportional to the 

amount of cover on the soil. The Universal Soil 

Loss Equation developed by the USDA Soil 

Conservation Service (now the Natural Resources 

Conservation Service) predicts that a soil cover of 

just 40 percent when winter arrives can reduce 

erosion substantially until spring. 

It’s worthwhile to get covers established early, 

to ensure that maximum soil cover develops 

before winter rains. Consider overseeding covers 

at layby cultivation, aerial seeding before harvest 

or planting as soon as possible after harvest. It’s 

also a good idea to maintain year-round soil cover 

whenever possible. 


ORGANIC MATTER ADDITIONS 

The benefits of organic matter include improved 

soil structure, increased infiltration and 

water-holding capacity, increased cation 

exchange capacity (the ability of the soil to act 

as a short-term storage bank for positively charged 

plant nutrients) and more efficient storage of 

nutrients. Without organic matter, you have no 

soil to speak of, only a dead mixture of ground-up 

and weathered rocks. 

Organic matter includes thousands of different 

substances derived from decayed leaves, roots, 

microorganisms, manure and even groundhogs 

that died in their burrows. These substances 

function in different ways to build healthy soil. 

Different plants leave behind different kinds of 

organic matter as they decompose,so your choice 

of cover crop will largely determine which soil 

benefits you will receive. 

Soil scientists may argue over how to classify 

the various soil organic components. Most will 

agree, however, that there is a portion that can be 

called the “active” fraction, and one that might 

be called the “stable” fraction, which is roughly 

equivalent to humus.There are many categories 

in between the active and stable fractions. 

The active fraction represents the most easily 

decomposed parts of soil organic matter. It tends 

to be rich in simple sugars and proteins and 

consists largely of recently added residues, microbial 

cells and the simpler waste products from 

microbial decay. 

Because microorganisms, like human organisms, 

crave sweet stuff, compounds containing 

simple sugars disappear quickly. Proteins also are 

selected quickly from the menu of edible soil 

goodies. When these compounds are digested, 

many of the nutrients that they contain are 

released into the soil. Proteins are nitrogen-rich, 

so the active fraction is responsible for the 

release of most N, as well as some K, P and other 

nutrients, from organic matter into the soil. 

The easily decomposed proteins and sugars burn 

up almost completely as energy sources, and 

don’t leave much behind to contribute to organic 

matter building. 

After the microorganisms have devoured the 

portions of the active fraction that are easiest to 

digest, a more dedicated subset of these microorganisms 

will start munching on the more complex 

and tough material, such as celluloses and 

lignins,the structural materials of plants.Since cellulose 

is tougher than simple sugars, and lignin 

breaks down very slowly,they contribute more to 

the humus or stable fraction. Humus is responsible 

for giving the soil that rich, dark, spongy feeling 

and for properties such as water retention and 

cation exchange capacity. 

Plant materials that are succulent and rich 

in proteins and sugars will release nutrients rapidly 

but leave behind little long-term organic matter. 

Plant materials that are woodier or more 

fibrous will release nutrients much more slowly, 

but will promote more stable organic matter, or 

humus, leading to better soil physical conditions, 

increased nutrient-holding capacity and higher 

cation exchange capacity. 

In general, annual legumes are succulent. 

They release nitrogen and other nutrients quickly 

through the active fraction, but are not very 

effective at building up humus. Long-term use 

of succulent annual legumes can increase 

soil humus, however, as recent research 

suggests (354). 

Grains and other grasses and nonlegumes will 

contribute to humus production, but won’t 

release nutrients very rapidly or in large 

quantities if incorporated as they approach maturity. 

Perennial legumes such as white and red 

clover may fall in both categories—their leaves 

will break down quickly, but their root systems 

may become tough and fibrous and can contribute 

to humus accumulation. 

Cover Crops Help “Glue” Soil 

As soil microorganisms digest plant material, they 

produce some compounds in addition to the 

active and stable fractions of the organic matter. 

One group of these by-products is known as 

polysaccharides.These are complex sugars that 

act as glues in the soil to cement small soil particles 

into clusters or aggregates. Many farmers 

use the term “crumb” to describe soil clusters 

BUILDING SOIL FERTILITY AND TILTH 17

about the size of a grain of rice. A wellaggregated 

or “crumby” soil—not to be confused 

with someone else’s crummy or depleted soil— 

has good aeration. It allows better infiltration and 

retention of water. 

Cover crops can promote good aggregation in 

the soil through increased production of these 

and other microbial glues, recent research has 

shown. See Cover Crops Can Stabilize Your Soil 

(p. 19). Well-aggregated soils also are less prone 

to compaction, which has been shown to reduce 

yields of vegetables such as snap beans, cabbage 

and cucumber by 50 percent or more (371). 

As they decompose, leguminous cover crops 

seem to be better than grasses for production of 

polysaccharides (6). However, polysaccharides 

will decompose in a matter of months, so their 

aggregation effect is likely to last only the season 

after the use of the cover crop. 

Grass species also promote good aggregation, 

but by a different mechanism. Grasses have a 

‘fibrous’ root system—made of numerous fine 

roots spreading out from the base of the plant. 

These roots may release compounds that help 

aggregate the soil between roots. 

Organic matter builds up very slowly in the 

soil. A soil with 3 percent organic matter might 

only increase to 4 percent after a decade or 

more of soil building. The benefits of increased 

organic matter, however, are likely to be apparent 

long before increased quantities are detectable. 

Some, such as enhanced aggregation, water infiltration 

rates and nutrient release,will be apparent 

the first season; others may take several years to 

become noticeable (354). 

Your tillage method is an important consideration 

when using cover crops to build soil,because 

tillage will affect the rate of organic matter accumulation. 

It is difficult to build up organic 

matter under conventional tillage regimes. 

Tillage speeds up organic matter decomposition 

by exposing more surface area to oxygen, warming 

and drying the soil, and breaking residue into 

smaller pieces with more surfaces that can be 

attacked by decomposers. Like fanning a fire, 

tillage rapidly “burns up” or “oxidizes” the fuel, 

which in this case is organic matter. The 

resulting loss of organic matter causes the breakdown 

of soil aggregates and the poor soil structure 

often seen in overtilled soil. 

When adding cover crops to a system, minimize 

tillage to maximize the long-term soil benefits. 

Many of the cover crops discussed in this 

book are ones you can seed into growing crops or 

no-till plant into crop residues. Otherwise, the 

gain in organic matter may be counteracted by 

higher decomposition rates. 

TIGHTENING THE NUTRIENT LOOP 

In addition to reducing topsoil erosion and improving 

soil structure, cover crops enhance nutrient 

cycling in your farming system by taking up nutrients 

that otherwise might leach out of the soil profile. 

These excess nutrients have the potential to 

pollute groundwater or local streams and ponds. 

Of the common plant nutrients, nitrogen in the 

nitrate form is the most water-soluble and therefore 

the most vulnerable to leaching. Anytime 

soil is bare and appreciable rain falls, nitrates are 

on the move. Nitrate can be present in the soil 

at the end of a cropping season if the crop did not 

use all the N applied. Decomposing organic matter 

(including plant residues, compost and animal 

manures) also can release nitrate-N, as long as the 

soil temperature is above freezing. Even in a field 

where the yearly application of N is well-suited to 

crop needs, nitrates can accumulate after crops 

are harvested and leach when it rains. 

Cover crops reduce nitrate leaching in two 

ways. They soak up available nitrate for their 

own needs. They also use some soil moisture, 

reducing the amount of water available to leach 

nutrients. 

The best cover crops to use for nitrate conservation 

are nonlegumes that form deep, extensive 

root systems quickly after cash crops are 

harvested. For much of the continental U.S., cereal 

rye is the best choice for catching nutrients 

after a summer crop. Its cold tolerance is a big 

advantage that allows rye to continue to grow in 

late fall and put down roots to a depth of three 

feet or more. Where winters are mild, rye can 

grow through the winter months. 

Research with soil high in residual N in the 

mid-Atlantic’s coastal plain showed that cereal rye 


Cover Crops Can Stabilize Your Soil 

The more you use cover crops, the better 

your soil tilth, research continues to show. 

One reason is that cover crops, especially 

legumes, encourage populations of beneficial 

fungi and other microorganisms that help 

bind soil aggregates. 

The fungi, called mycorrhizae, produce a 

water-insoluble protein known as glomalin, 

which catches and glues together particles of 

organic matter, plant cells, bacteria and other 

fungi, recent research suggests (372). 

Glomalin may be one of the most important 

substances in promoting and stabilizing soil 

aggregates. 

Most plant roots, not just those of cover 

crops, develop beneficial mycorrhizal 

relationships.The fungi send out rootlike 

extensions called hyphae, which take up 

water and soil nutrients to help feed plants. 

In low-phosphorus soils, for example, the 

hyphae can increase the amount of 

phosphorus that plants obtain. In return, the 

fungi receive energy in the form of sugars 

that plants produce in their leaves and send 

down to the roots. 

Growing a cover crop increases the 

abundance of mycorrhizal spores. Legumes 

in particular can contribute to mycorrhizal 

diversity and abundance, because their roots 

tend to develop large populations of these 

beneficial fungi. 

By having their own mycorrhizal fungi and 

by promoting mycorrhizal relationships in 

subsequent crops, cover crops therefore can 

play a key role in improving soil tilth.The 

overall increase in glomalin production also 

could help explain why cover crops can 

improve water infiltration into soil and 

enhance storage of water and soil nutrients, 

even when there has been no detectable 

increase in the amount of soil organic 

matter. 

took up more than 70 lb. N/A in fall when planted 

by October 1. Other grasses, including wheat, 

oats, barley and ryegrass, were only able to take 

up about half that amount in fall. Legumes were 

practically useless for this purpose in the 

Chesapeake Bay study (30). Legumes tend to 

establish slowly in fall and are mediocre N 

scavengers, as they can fix much of their own N. 

To maximize N uptake and prevent leaching, 

plant nonlegumes as early as possible. In the 

above study, rye took up only 15 lb. N/A when 

planting was delayed until November. It is important 

to give cover crops the same respect as any 

other crop in the rotation and plant them in a 

timely manner. 

Not Just Nitrogen Cycling 

Cover crops help bring other nutrients back into 

the upper soil profile from deep soil layers. 

Calcium and potassium are two macronutrients 

with a tendency to travel with water, though not 

generally on the express route with N. These 

nutrients can be brought up from deeper soil layers 

by any deep-rooted cover crop.The nutrients 

are then released back into the active organic matter 

when the cover crop dies and decomposes. 

Although phosphorus (P) doesn’t generally 

leach, as it is only slightly water-soluble, cover 

crops may play a role in increasing its availability 

in the soil. Some covers, such as buckwheat and 

lupins, are thought to secrete acids into the soil 

that put P into a more soluble, plant-usable form. 

Some cover crops enhance P availability in 

another manner. The roots of many common 

cover crops, particularly legumes, house beneficial 

fungi known as mycorrhizae. The mycorrhizal 

fungi have evolved efficient means of 

absorbing P from the soil, which they pass on to 

their plant host.The filaments (hyphae) of these 

fungi effectively extend the root system and help 

the plants tap more soil P. 

Keeping phosphorus in an organic form is the 

most efficient way to keep it cycling in the soil. 

So the return of any plant or animal residue to the 


soil helps maintain P availability. Cover crops 

help retain P in your fields by reducing erosion. 

Adding Nitrogen 

One of nature’s most gracious gifts to plants and 

soil is the way that legumes, with the help of rhizobial 

bacteria, can add N to enrich your soil. If 

you are not familiar with how this remarkable 

process works, see Nodulation: Match Inoculant 

to Maximize N (p. 92). 

The nitrogen provided by N-fixation is used 

efficiently in natural ecosystems, thanks to the 

soil’s complex web of interacting physical, chemical 

and biological processes. In an agricultural 

system, however, soil and crop management 

factors often interfere with nature’s ultra-efficient 

use of organic or inorganic N. Learning a bit 

about the factors affecting N-use efficiency from 

legume plants will help build the most sustainable 

cropping system possible within your constraints. 

How Much N is Fixed 

A number of factors determine how much of the 

N in your legume came from “free” N, fixed from 

N2 gas: 

• Is the symbiosis (the interdependence of 

the rhizobia and the plant roots) effective See 

Nodulation: Match Inoculant to Maximize N (p. 

92). Use the correct rhizobial inoculant for the 

legume you’re growing. Make sure it’s fresh, was 

stored properly, and that you apply it with an 

effective sticking agent. Otherwise, there will be 

few nodules and N-fixation will be low. 

• Is the soil fertile N-fixation requires iron, sulfur 

and molybdenum to function properly. Soils 

depleted of these micronutrients will not support 

efficient fixation. Tissue testing your cash crops 

can help you decide if you need to adjust 

micronutrient levels. 

• Is the soil getting enough air N-fixation 

requires that N-rich air get to the legume roots. 

Waterlogging or compaction hampers the movement 

of air into the soil. Deep-rooted cover crops 

can help alleviate subsoil compaction (371). 

• Is the pH adequate Rhizobia generally will 

not live long in soils below pH 5. 

• Does the legume/rhizobial pair have high fixation 

potential Not all legumes were created 

equal—some are genetically inferior when it 

comes to fixation. Beans (Phaseolus spp.) are 

notoriously incapable of a good symbiotic relationship 

and are rarely able to fix much more than 

40 lb. N/A in a whole season. Cowpeas (Vigna 

unguiculata) and vetches (Vicia spp.), on the 

other hand, are generally capable of high fixation 

rates. Check Chart 2 Performances and Roles 

(p. 48) and the sections on individual cover crops 

for information about their N-fixation potential. 

Even under the best of conditions, legumes 

rarely fix more than 80 percent of the nitrogen 

they need to grow,and may only fix as much as 40 

or 50 percent. The legume removes the rest of 

what it needs from the soil like any other plant. 

Legumes have to feed the bacteria to get them to 

work, so if there is ample nitrate already available 

in the soil,a legume will remove much of that first 

before expending the energy to get N-fixation 

going. In soils with high N fertility, legumes may 

fix little or no nitrogen.See How Much N (p.22). 

While it is tempting to think of legume nodules 

as little fertilizer factories pumping N into the 

surrounding soil, that isn’t what happens. The 

fixed N is almost immediately shunted up into the 

stems and leaves of the growing legume to form 

proteins, chlorophyll and other N-containing 

compounds.The fixed nitrogen will not become 

available to the next crop until the legume 

decomposes. Consequently, if the aboveground 

part of the legume is removed for hay, the majority 

of the fixed nitrogen also leaves the field. 

What about the legume roots Under conditions 

favoring optimal N fixation, a good rule of 

thumb is to think of the nitrogen left in the plant 

roots (15 to 30 percent of plant N) as being 

roughly equivalent to the amount the legume 

removed directly from the soil, and the amount in 

the stems and leaves as being equivalent to what 

was fixed. 

Annual legumes that are allowed to flower and 

mature will transport a large portion of their 

biomass nitrogen into the seeds or beans. Also, 

once the legume has stopped actively growing, it 

will shut down the N-fixing symbiosis. In annual 

legumes this occurs at the time of flowering; no 

additional N gain will occur after that point. 

Unless you want a legume to reseed itself, it’s 


generally a good idea to kill a legume cover crop 

in the early- to mid-blossom stage. You’ll have 

obtained maximum legume N and need not delay 

planting of the following cash crop any further, 

aside from any period you may want for 

residue decomposition as part of your seedbed 

preparation. 

How Nitrogen is Released 

How much N will soil really acquire from a 

legume cover crop Let’s take it from the point of 

a freshly killed, annual legume, cut down in its 

prime at mid-bloom. The management and 

climatic events following the death of that legume 

will greatly affect the amount and timing of N 

release from the legume to the soil. 

Most soil bacteria will feast on and rapidly 

decompose green manures such as annual 

legumes, which contain many simple sugars and 

proteins as energy sources. Soil bacteria love to 

party and when there is lots to eat, they do something 

that no party guest you’ve ever invited can 

do—they reproduce themselves, rapidly and 

repeatedly,doubling their population in as little as 

seven days under field conditions (246). Even a 

relatively inactive soil can come to life quickly 

with addition of a delectable green manure. 

The result can be a very rapid and large release 

of nitrate into the soil within a week of the green 

manure’s demise. This N release is more rapid 

when covers are plowed down than when left on 

the surface. As much as 140 lb. N/A has been 

measured 7 to 10 days after plowdown of hairy 

vetch (303). Green manures that are less proteinrich 

(N-rich) will take longer to release N. 

Those that are old and fibrous or woody are generally 

left for hard-working but somewhat sluggish 

fungi to convert slowly to humus over the 

years, gradually releasing small amounts of 

nutrients. 

Other factors contribute significantly to how 

quickly a green manure releases its N. Weather 

has a huge influence. The soil organisms responsible 

for decomposition work best at warm 

temperatures and are less energetic during cool 

spring months. 

Soil moisture also has a dramatic effect. 

Research shows that soil microbial activity peaks 

when 60 percent of the soil pores are filled 

with water, and declines significantly when moisture 

levels are higher or lower (193). This 60 

percent water-filled pore space roughly corresponds 

to field capacity, or the amount of water 

left in the soil when it is allowed to drain for 24 

hours after a good soaking rain. 

Microbes are sensitive to soil chemistry as well. 

Most soil bacteria need a pH of between 6 and 8 

to perform at peak;fungi (the slow decomposers) 

are still active at very low pH.Soil microorganisms 

also need most of the same nutrients as plants 

require, so low-fertility soils support smaller populations 

of primary decomposers, compared with 

high-fertility soils. Don’t expect N-release rates or 

fertilizer replacement values for a given cover 

crop to be identical in fields of different fertility. 

Many of these environmental factors are out of 

your direct control in the near term. Management 

factors such as fertilization, liming and tillage, 

however, also influence production and availability 

of legume N. 

Tillage, No-Tillage and N-Cycling 

Tillage affects decomposition of plant residues in 

a number of ways. First, any tillage increases soil 

contact with residues and increases the microbes’ 

access to them. The plow layer is a hospitable 

environment for microbes, as they’re sheltered 

from extremes of temperature and moisture. 

Second, tillage breaks the residue into smaller 

pieces, providing more edges for microbes to 

munch. Third, tillage will temporarily decrease 

the density of the soil, generally allowing it to 

drain and therefore warm up more quickly. All 

told, residues incorporated into the soil tend to 

decompose and release nutrients much faster 

than those left on the surface, as in a no-till system.That’s 

not necessarily good news, however. 

A real challenge of farming efficiently is to keep 

as much of the N as possible in a stable, storable 

form until it’s needed by the crop. The best 

storage form of N is the organic form: the undecomposed 

residue, the humus or the microorganisms 

themselves. 

Let’s consider the N contained in the microbes. 

Nitrogen is a nutrient the microbes need for building 

proteins and other compounds. Carbon-con- 


How Much N 

To find out if you might need more N than 

your green manure supplied, you need to 

estimate the amount of N in your cover crop. 

To do this, assess the total yield of the green 

manure and the percentage of N in the plants 

just before they die. 

To estimate yield, take cuttings from several 

areas in the field, dry and weigh them. Use a 

yardstick or metal frame of known dimensions 

and clip the plants at ground level within the 

known area. Dry them out in the sun for a few 

consecutive days, or use an oven at about 140 

F for 24 to 48 hours until they are “crunchy 

dry.” Use the following equation to determine 

per-acre yield of dry matter: 

Yield (lb.)/Acre = Total weight of dried samples (lb.) X 

43,560 sq. ft. 

# square feet you sampled 1 Acre 

While actually sampling is more accurate, 

you can estimate your yield from the height of 

your green manure crop and its percent 

groundcover. Use these estimators: 

At 100 percent groundcover and 6-inch 

height*, most nonwoody legumes will contain 

roughly 2,000 lb./A of dry matter. For each 

additional inch, add 150 lb. So, a legume that is 

18 inches tall and 100 percent groundcover 

will weigh roughly: 

Inches >6: 18 in.–6 in. = 12 in. 

x 150 lb./in.: 12 in. x 150 lb./in. = 1,800 lb. 

Add 2,000 lb.: 2,000 lb. + 1,800 lb. = 3,800 lb. 

If the stand has less than 100 percent 

groundcover, multiply by (the percent ground 

cover / 100). In this example, for 60 percent 

groundcover, you would obtain: 

3,800 x (60/100) = 2,280 lb. 

Keep in mind that these are rough 

estimates to give you a quick guide for the 

productivity of your green manure.To know 

the exact percent N in your plant tissue, you 

would have to send it to a lab for analysis. 

Even with a delay for processing, the results 

could be helpful for the crop if you use split 

applications of N.Testing is always a good idea, 

as it can help you refine your N estimates for 

subsequent growing seasons. 

The following rules of thumb may help here: 

• Annual legumes typically have between 

3.5 and 4 percent N in their aboveground 

parts prior to flowering (for young material, 

use the higher end of the range), and 3 to 3.5 

percent at flowering.After flowering, N in the 

leaves decreases quickly as it accumulates in 

the growing seeds. 

* For cereal rye, the height relationship is a bit different. Cereal rye 

weighs approximately 2,000 lb./A of dry matter at an 8-inch height 

and 100 percent groundcover. For each additional inch, add 150 

lb., as before, and multiply by (percent groundcover/100). 

For most small grains and other annual grasses, start with 

2,000 lb./A at 6 inches and 100 percent ground cover.Add 

300 lb. for each additional inch and multiply by (percent 

groundcover/100). 

taining compounds such as sugars are mainly 

energy sources, which the microorganisms use as 

fuel to live. The process of burning this fuel 

sends most of the carbon back into the atmosphere 

as carbon dioxide, or CO2. 

Suppose a lot of new food is suddenly put into 

the soil system, as when a green manure is 

plowed down. Bacteria will expand their 

populations quickly to tap the carbon-based 

energy that’s available. All the new bacteria, 

though, will need some N, as well as other nutrients,for 

body building before they can even begin 

to eat. So any newly released or existing mineral 

N in soil gets scavenged by new bacteria. 

Materials with a high carbon to nitrogen (C:N) 

ratio, such as mature grass cover crops, straw or 

any fibrous, woody residue, have a low N content.They 

can “tie up” soil N, keeping it immobilized 

(and unavailable) to crops until the 

carbon “fuel supply” starts depleting.Tie-up may 

last for several weeks in the early part of the 

growing season, and crop plants may show the 

yellowing characteristic of N deficiencies. That 

is why it often makes sense to wait one to three 


• For perennial legumes that have a 

significant number of thick, fibrous or woody 

stems, reduce these estimates by 1 percent. 

• Most cover crop grasses contain 2 to 3 

percent N before flowering and 1.5 to 2.5 

percent after flowering. 

• Other covers, such as brassicas and 

buckwheat, will generally be similar to, or 

slightly below, grasses in their N content. 

To put it all together: 

Total N in green manure (lb./A) = yield (lb./A) x % N 

100 

To estimate what will be available to your 

crop this year, divide this quantity of N by: 

• 2, if the green manure will be 

conventionally tilled; 

• 4, if it will be left on the surface in a no-till 

system in Northern climates; 

• 2, if it will be left on the surface in a no-till 

system in Southern climates. 

Bear in mind that in cold climates,N will 

mineralize more slowly than in warm climates, 

as discussed above.So these are gross estimates 

and a bit on the conservative side. 

Of course, cover crops will not be the only 

N sources for your crops.Your soil will release 

between 10 and 40 lb. N/A for each 1 percent 

organic matter. Cold, wet clays will be at the 

low end of the scale and warm, well-drained 

soils will be at the high end.You also may 

receive benefits from last year’s manure, green 

manure or compost application. 

Other tools could help you refine your 

nitrogen needs. On-farm test strips of cover 

crops receiving different N rates would be an 

example. Refer to Appendix A, Testing Cover 

Crops on Your Farm (p. 156) for some tips on 

designing an on-farm trial. In some regions, a 

pre-sidedress N test in spring could help you 

estimate if supplemental N will be costeffective. 

Bear in mind that pre-sidedress 

testing does not work well when fresh plant 

residues have been turned in—too much 

microbial interference relating to N tie-up may 

give misleading results. 

For more information on determining 

your N from green manures and other 

amendments, see the Northeast Cover Crop 

Handbook, or the Farmers’ Fertilizer 

Handbook, listed in Appendix C (p. 164). 

—Marianne Sarrantonio, Ph.D. 

weeks after killing a low-N cover before planting 

the next crop, or to supplement with a more 

readily available N source when a delay is not 

practical. 

Annual legumes have low C:N ratios, such 

as 10:1 or 15:1. When pure stands of annual 

legumes are plowed down,the N tie-up may be so 

brief you will never know it occurred. 

Mixed materials,such as legume-grass mixtures, 

may cause a short tie-up, depending on the C:N 

ratio of the mixture. Some N storage in the microbial 

population may be advantageous in keeping 

excess N tied up when no crop roots are there to 

absorb it. 

Fall-planted mixtures are more effective in 

immobolizing excess soil N than pure legumes 

and, as stated earlier, the N is mineralized more 

rapidly from mixtures than from pure grass. A 

fall-seeded mixture will adjust to residual soil N 

levels.When the N levels are high, the grass will 

dominate and when N levels are low, the legume 

will dominate the mixtures.This can be an effective 

management tool to reduce leaching while 

making the N more available to the next crop. 

Potential Losses 

A common misunderstanding about using green 

manure crops is that the N is used more 

efficiently because it’s from a plant source. This 

is not necessarily true. Nitrogen can be lost from 

a green manure system almost as easily as from 

chemical fertilizers, and in comparable amounts. 


The reason is that the legume organic N may be 

converted to ammonium (NH4 + ), then to ammonia 

(NH3) or nitrate (NO3 - ) before plants can take it up. 

Under no-till systems where killed cover crops 

remain on the surface, some ammonia (NH3) gas 

can be lost right back into the atmosphere. 

Nitrate is the form of N that most plants prefer. 

Unfortunately, it is also the most water-soluble 

form of N. Whenever there is more nitrate than 

plant roots can absorb, the excess may leach with 

heavy rain or irrigation water. 

As noted earlier, nitrates in excess of 140 lb./A 

may be released into warm,moist soil within as little 

as seven to 10 days after plowing down a high- 

N legume, such as a hairy vetch stand. Since the 

following crop is unlikely to have much of a root 

system at that point, the N has a ticket for 

Leachville. Consider also that the green manure 

may have been plowed down to as deep as 12 

inches—much deeper than anyone would consider 

applying chemical fertilizer. Moreover, 

green manures sometimes continue to decompose 

after the cash crop no longer needs N.This 

N also is prone to leaching. 

To summarize, conventional plowing and 

aggressive disking can cause a rapid decomposition 

of green manures, which could provide too 

much N too soon in the cropping season. No-till 

systems will have a reduced and more gradual 

release of N, but some of that N may be vulnerable 

to gaseous loss, either by ammonia volatilization 

or by denitrification. Thus, depending on 

management, soil and weather situations, N from 

legume cover crops may not be more efficiently 

used than N from fertilizer. 

Some possible solutions to this cover crop 

nitrogen-cycling dilemma: 

• A shallow incorporation of the green manure, 

as with a disk,may reduce the risk of gaseous loss. 

• It may be feasible to no-till plant into the 

green manure, then mow or incorporate it 

between the rows several weeks later, when cash 

crop roots are more developed and able to take 

up N. This has some risk, especially when soil 

moisture is limiting, but can provide satisfactory 

results if seedling survival is assured. 

• Residue from a grass/legume mix will have a 

higher C:N than the legume alone, slowing the 

release of N so it’s not as vulnerable to loss. 

Consider also that some portion of the N in the 

green manure will be conserved in the soil in an 

organic form for gradual release in a number of 

subsequent growing seasons. 

OTHER SOIL-IMPROVING BENEFITS 

Cover crops can be very useful as living plows to 

penetrate and break up compacted layers in the 

soil. Some of the covers discussed in this book, 

such as sweetclover, have roots that reach as 

deep as three feet in the soil within one cropping 

season.The action of numerous pointy little 

taproots with the hydraulic force of a determined 

plant behind them can penetrate soil 

where plowshares fear to go. Grasses, with their 

tremendously extensive root systems, may 

relieve compacted surface soil layers. Sorghumsudangrass 

can be managed to powerfully fracture 

subsoil. See Summer Covers Relieve 

Compaction (p. 84). 

One of the less appreciated soil benefits of 

cover crops is an increase in the total numbers 

and diversity of soil organisms.As discussed earlier, 

diversity is the key to a healthy, well-functioning 

soil. Living covers help supply 

year-round food for organisms that feed off root 

by-products or that need the habitat provided on 

a residue-littered soil surface. Dead covers 

supply a more varied and increased soil diet for 

many organisms. 

Of course, unwanted pests may be lured to the 

field. Effective crop rotations that include cover 

crops, however, tend to reduce rather than 

increase pest concerns. Pest-management considerations 

due to the presence of a cover crop are 

discussed in the next chapter, Managing Pests 

with Cover Crops (p. 25). 

Finally, cover crops may have an added advantage 

of drying out and therefore warming soils 

during a cold, wet season.The flip side of this is 

that they may dry the soil out too much and rob 

the following crop of needed moisture. 

There are no over-the-counter elixirs for renewing 

soil. A long-term farm plan that includes 

cover crops, however, can help ensure your soil’s 

health and productivity for as long as you farm. 


MANAGING PESTS WITH COVER CROPS 

By Sharad C. Phatak 

Crop crops are poised to play increasingly 

important roles on North American farms. 

In addition to slowing erosion, improving 

soil structure and providing fertility, we are learning 

how cover crops help farmers to manage 

pests. With limited tillage and careful attention 

to cultivar choice, placement and timing, cover 

crops can reduce infestations by insects, diseases, 

nematodes and weeds. Pest-fighting cover crop 

systems help minimize reliance on pesticides,and 

as a result cut costs, reduce your chemical exposure, 

protect the environment, and increase consumer 

confidence in the food you produce. 

Farmers and researchers are using cover crops 

to design new strategies that preserve a farm’s 

natural resources while remaining profitable. Key 

to this approach is to see a farm as an “agroecosystem”—a 

dynamic relationship of the mineral, 

biological, weather and human resources 

involved in producing crops or livestock.Our goal 

is to learn agricultural practices that are environmentally 

sound,economically feasible and socially 

acceptable. 

Environmentally sustainable pest management 

starts with building healthy soils. Research in 

south Georgia (see sidebar Georgia Cotton, 

Peanut Farmers, p. 26) shows that crops grown 

on biologically active soils resist pest pressures 

better than those grown on soils of low fertility, 

extreme pH, low biological activity and poor soil 

structure. 

There are many ways to increase biological 

activity in soil. Adding more organic material by 

growing cover crops or applying manure helps. 

Reducing or eliminating pesticides favors diverse, 

healthy populations of beneficial soil flora and 

fauna. So does reducing or eliminating tillage that 

causes losses of soil structure, biological life or 

organic matter. These losses make crops more 

vulnerable to pest damage. 

Farming on newly cleared land shows the 

process well. Land that has been in a “cover crop” 

of trees or pastures for at least 10 years remains 

productive for row crops and vegetables for the 

first two to three years. High yields of agronomic 

and horticultural crops are profitable, with 

comparatively few pesticide and fertilizer inputs. 

After that—under conventional systems with customary 

clean tillage—annual crops require higher 

inputs.The first several years of excessive tillage 

destroys the food sources and micro-niches on 

which the soil organisms that help suppress pests 

depend. When protective natural biological 

systems are disrupted, pests have new openings 

and crops are much more at risk. 

Cover crop farming is different from clean-field 

monocropping, where perfection is rows of corn 

or cotton with no thought given to encouraging 

other organisms.Cover crops bring more forms of 

life into the picture and into your management 

plan. By working with a more diverse range of 

crops,some growing at the same time in the same 

field, you’ve got a lot more options. Here’s a quick 

overview of how these systems work. 

Insect Management 

In balanced ecosystems, insect pests are kept in 

check by their natural enemies. These natural 

pest controls—called beneficials in agricultural 

systems—include predator and parasitoid insects 

and diseases. Predators kill and eat other insects; 

parasitoids spend their larval stage inside another 

insect, which then dies as the invader’s larval 

stage ends. However, in conventional systems, 

synthetic chemical treatments that kill insect 

pests also typically kill their natural enemies. 

Conserving and encouraging beneficial organisms 

is key to achieving sustainable pest management. 

You should aim to combine strategies that make 

each farm field more hospitable to beneficials. 

Reduce pesticide use, and, when use is essential, 

select materials that are least harmful to beneficials. 

Avoid or minimize cultural practices such as tilling 

and burning that kill beneficials and destroy their 

habitat. Build up the sustenance and habitat that 

beneficials need. Properly managed cover crops 

MANAGING PESTS WITH COVER CROPS 25

Georgia Cotton, Peanut Farmers Use Cover Crops to Control Pests 

TIFTON, Ga.—Here in southwestern Georgia, a cover crop of rye, crimson clover, cahaba 

I’m working with farmers who have had 

vetch or subterranean clover. 

dramatic success creating biologically active Spring—Strip-till rows 18 to 24 inches wide, 

soil in fields that have been conventionally leaving the cover crop growing between the 

tilled for generations.We still grow the 

strips.Three weeks later,plant cotton. 

traditional cash crops of cotton and peanuts, • Year 2. Fall—Replant cereal rye or cahaba 

but with a difference.We’ve added cover 

vetch, allow crimson or subclover hard seed 

crops, virtually eliminated tillage, and added to germinate. 

new cash crops that substitute for cotton 

Spring—Strip-till cotton. 

and peanuts some years to break disease 

• Year 3. Fall—Plant rye. 

cycles and allow for more biodiversity. 

Spring—Desiccate rye with herbicides. 

Our strategies include no-till planting (using No-till plant peanuts. 

modified conventional planters), permanent • Year 4. Year 1 starts the cycle again. 

planting beds, controlled implement traffic, Vegetable farmers frequently use fall-planted 

crop rotation and annual high-residue winter cereal rye plowed down before vegetables, 

cover crops.We incorporate fertilizer and or crimson clover strip-tilled before planting 

lime prior to the first planting of rye in the vegetables.The crimson clover matures, 

conversion year. This is usually the last tillage drops hard seed, then dies. Most of the seed 

we plan to do on these fields for many years. germinates in fall. Cereal/legume mixes have 

Together, these practices give us significant not been more successful than single-crop 

pest management benefits within three years. cover crop plantings in our area. 

Growers are experimenting with a basic 

Some vegetable farmers strip-till rows into 

winter cover crop>summer cash crop 

rye in April. The strips are planted in early 

rotation. Our cover crops are ones we 

May to Southern peas, lima beans or snap 

know grow well here. Rye provides control of beans. Rye in row middles will be dead or 

disease, weed and nematode threats. Legume nearly dead. Rye or crimson clover can 

crops are crimson clover, subterranean clover continue the rotation. 

or cahaba vetch.They are planted with the 

Vegetable farmers also broadcast crimson 

rye or along field borders, around ponds, near clover in early March. They desiccate the 

irrigation lines and in other non-cropped areas cover, strip-till rows, then plant squash in April. 

as close as possible to fields to provide the The clover in the row middles will set seed 

food needed to support beneficials at higher then die back through summer. The crimson 

populations. 

strips will begin to regrow in fall from the 

When I work with area cotton and peanut dropped seed, and fall vegetables may be 

farmers who want to diversify their farms, we planted in the tilled areas after the July squash 

set up a program that looks like this: 

harvest. 

• Year 1. Fall—Adjust fertility and pH 

Insecticide and herbicide reduction begins 

according to soil test. Deep till if necessary the first year, with no applications needed 

to relieve subsurface soil compaction. Plant by the third or fourth year in many cases. 

supply moisture, physical niches and food in the 

form of insects,pollen,honeydew and nectar. 

By including cover crops in your rotations and 

not spraying insecticides, beneficials often are 

already in place when you plant spring or summer 

crops.However,if you fully incorporate cover 

crops, you destroy or disperse most of the beneficials 

that were present. Conservation tillage is a 


The farmers get weed control by flail mowing 

herbicide-killed, fall-planted rye, leaving about 

6 inches of stubble. One or two post-emerge 

herbicide applications should suffice in the 

first few years. I don’t recommend cultivation 

for weed control because it increases risks of 

soil erosion and damages the protective outer 

leaf layer that helps prevent plant diseases. 

We see changes on farms where the 

rotations stay in place for three or more years: 

• Insects. Insecticide costs are $50 

to $100/A less than conventional crop 

management in the area for all kinds of 

crops.The farmers using the alternative 

system often substitute with insect control 

materials such as Bacillus thuringiensis (Bt), 

pyrethroids and insect growth regulators 

that have less severe environmental impact. 

These products are less persistent in the field 

environment, more targeted to specific pests 

and do less harm to beneficials. By planting 

cover crops on field edges and in other noncrop 

areas, these farmers are increasing the 

numbers of beneficials in the field 

environments. 

Pests that are no longer a problem on the 

cover-cropped farms include thrips, bollworm, 

budworm, aphids, fall armyworm, beet 

armyworm and white flies. On my no-till 

research plots with cover crops and long 

rotations, I’ve not used insecticides for six years 

on peanuts, for eight years on cotton and for 12 

years on vegetables. I’m working with growers 

who use cover crops and crop rotations to 

economically produce cucumbers, squash, 

peppers, eggplant, cabbage peanuts, soybeans 

and cotton with only one or two applications 

of insecticide—sometimes with none. 

• Weeds. Strip-tilling into over-wintered 

cover crops provides acceptable weed 

control for relay-cropped cucumbers (264). 

Conventional management of rye in our area 

is usually to disk or kill it with broadspectrum 

herbicides such as paraquat or 

glyphosate. 

• Diseases. I’ve been strip-tilling crimson 

clover since 1985 to raise tomatoes, peppers, 

eggplant, cucumbers, cantaloupes, lima beans, 

snap beans, Southern peas and cabbages. I’m 

using no fungicides. Our research staff has 

raised peanuts no-tilled into cereal rye for the 

past six years, also without fungicides. 

• Nematodes. If we start on land where 

pest nematodes are not a major problem, 

this system keeps them from becoming a 

problem. 

Even though the conventional wisdom says 

you can’t build organic matter in our climate 

and soils, we have top-inch readings of 4 

percent organic matter in a field that tested 

0.5 percent four years ago. 

We are still learning,but know that we can 

rotate crops,use cover crops and cut tillage 

to greatly improve our sustainability.In our 

experience,we’ve reduced total costs by as 

much as $200 per acre for purchased inputs 

and tillage.Parts of our system will work in 

many places.Experiment on a small scale to 

look more closely at what’s really going in your 

soil and on your crops. As you compare insights 

and share information with other growers and 

researchers in your area,you’ll find cover crops 

that help you control pests,too. 

—Sharad C. Phatak 

better option because it leaves more of the cover 

crop residue on the surface. No-till planting only 

disturbs an area 2 to 4 inches wide,while strip-tilling 

disturbs an area up to about 24 inches wide 

between undisturbed row middles. 

Cover crops left on the surface may be living, 

temporarily suppressed, dying or dead. In any 

event, their presence protects beneficials and 

their habitat. The farmer-helpful organisms are 

hungry, ready to eat the pests of cash crops that 


are planted into the cover-crop residue. The 

ultimate goal is to provide year-round food and 

habitat for beneficials to ensure their presence 

within or near primary crops. 

We’re just beginning to understand the effects 

of cropping sequences and cover crops on beneficial 

and insect pest populations. Researchers 

have found that generalist predators, which feed 

on many species, may be an important biological 

control. During periods when pests are scarce or 

absent, several important generalist predators 

can subsist on nectar, pollen and alternative prey 

afforded by cover crops. This suggests you can 

enhance the biological control of pests by using 

cover crops as habitat or food for the beneficials 

in your area. 

This strategy is important for farmers in the 

South, where pest pressure can be especially 

heavy. In south Georgia, research showed that 

populations of beneficial insects such as insidious 

flower bugs (Orius insidiosus), bigeyed bugs 

(Geocoris spp.) and various lady beetles 

(Coleoptera coccinellidae) can attain high densities 

in various vetches, clovers and certain cruciferous 

crops. These predators subsisted and 

reproduced on nectar, pollen, thrips and aphids, 

and were established before key pests arrived. 

Research throughout Georgia, Alabama and 

Mississippi showed that when summer vegetables 

were planted amid “dying mulches”of cool-season 

cover crops, some beneficial insects moved in to 

attack crop pests. 

Recent research has looked carefully at how 

beneficials and crops interact. In undisturbed, 

biodiverse settings, the interactions are complex 

and intricate. Crop plants, when attacked by 

pests, send signals to which other insects 

respond. Appropriate beneficials move in to 

find their prey (349). 

Maximizing natural predator-pest interaction is 

the primary goal of biologically based Integrated 

Pest Management (IPM),and cover crops can play 

a leading role. For example: 

• Colorado potato beetle were observed at 9 

a.m. attacking eggplant that had been strip-till 

planted into crimson clover. By noon, assassin 

bugs had clustered around the feeding beetles. 

The beneficial bugs destroyed all the beetles by 

evening. 

• Cucumber beetles seen attacking cucumber 

plants were similarly destroyed by beneficials 

within a day. 

• Lady beetles in cover crop systems help to 

control aphids attacking many crops. 

Properly selected and managed, cover crops 

can enhance the soil and field environment to 

favor beneficials. Success depends on properly 

managing the cover crop species matched 

with the cash crops and anticipated pest threats. 

While we don’t yet have prescription plantings 

guaranteed to bring in all the needed beneficials—and 

only beneficials—for long lists of cash 

crops, we know some associations : 

• We identified 13 known beneficial insects 

associated with cover crops during one growing 

season in south Georgia vegetable plantings (34, 

36, 39). 

• In cotton fields in south Georgia where 

residues are left on the surface and insecticides 

are not applied, more than 120 species of beneficial 

arthropods, spiders and ants have been 

observed. 

• Fall-sown and spring-sown insectory mixes 

with 10 to 20 different cover crops work well 

under orchard systems. These covers provide 

habitat and alternative food sources for beneficial 

BUCKWHEAT grows quickly in cool, moist weather. 


insects. This approach has been used successfully 

by California almond and walnut growers participating 

in the Biologically Intensive Orchard 

Systems (BIOS) project of the University of 

California (142). 

The level of ecological sustainability depends 

on the grower’s interests, management skills and 

situation. Some use no insecticides while others 

have substantially reduced insecticide applications 

on peanut, cotton and vegetable crops. 

• In Georgia, Mississippi and South Carolina, 

minimally tilled crimson clover or cahaba vetch 

before cotton planting have been successful in 

reducing fertilizer N up to 50 percent and insecticide 

inputs by 30 to 100 percent. 

• Many farmers are adopting a system of transplanting 

tomatoes, peppers and eggplant into a 

killed hairy vetch or vetch/ 

rye cover crop. Benefits 

include weed, insect and disease 

suppression, improved 

fruit quality and overall lower 

production cost. 

• Leaving “remnant 

strips” of a cover when most of the crop is 

mowed or incorporated provides a continuing 

refuge and food source for beneficials, which 

might otherwise leave the area or die. This 

method is used in orchards when continued 

growth of cover crops would cause moisture 

competition with trees. 

• Insect movement is orchestrated in a system 

developed by Oklahoma State University for 

pecan growers. As legume mixtures senesce, 

beneficials migrate into trees to help suppress 

harmful insects. Not mowing the covers from 

August 1 until shuck split of the developing 

pecans lessens the unwanted movement of stink 

bugs, a pest which can damage green pecans 

(209). In California, lygus bugs on berseem clover 

or alfalfa are pests of cash crops. Be careful that 

cover crop maturity or killing a cover doesn’t 

force pests into a neighboring cash crop. 

Disease Management 

Growers traditionally have been advised to turn 

under plant debris by moldboard plowing to 

Cover crops can enhance the 

soil and field environment 

to favor beneficial insects. 

minimize disease losses (259, 260, 331, 333, 334). 

Now we realize that burying cover crop residues 

and disrupting the entire soil profile eliminates 

beneficial insect habitat and weed control benefits. 

The increased use of conservation tillage 

increases the need to manage crop disease without 

burying cover crops. 

Plant infection by microorganisms is rare (254). 

A pathogen has to cross many barriers before it 

can cause a disease to roots, stem or leaves.You 

can use cover crops to reinforce two of these 

barriers. 

Plant cuticle layer. This often waxy surface layer 

is the first physical barrier to plant infection. 

Many pathogens and all bacteria enter the plant 

through breaks, such as wounds, or natural openings, 

such as stomata, in this 

cuticle layer. This protective 

layer can be physically damaged 

by cultivation, spraying 

and sand-blasting from wind 

erosion, as well as by the 

impact and soil splashing 

from raindrops and overhead irrigation. In welldeveloped 

minimum-till or no-till crop systems 

with cover crops, you may not need cultivation 

for weed control (see below) and you can minimize 

spraying.Organic mulches from living,dying 

or killed covers that hold soil and stop soil splashing 

protect crops from injury to the cuticle. 

Plant surface microflora. Many benign organisms 

are present on the leaf and stem surface. 

They compete with pathogens for a limited supply 

of nutrients.Some of these organisms produce 

natural antibiotics. Pesticides, soaps, surfactants, 

spreaders and sticking agents can kill or disrupt 

the activities of these beneficial microorganisms, 

weakening the plant’s defenses. Cover crops can 

help this natural protection process work by 

reducing the need for synthetic crop protection 

materials. Further, cover crop plant surfaces can 

support healthy populations of beneficial 

microorganisms, including types of yeasts, that 

can migrate onto a cash crop after planting or 

transplanting. 


Select Covers that Balance Pests, Problems of Farm 

Many crops can be managed as cover crops, including cotton, soybean and most 

but only a few have been studied specifically vegetables. Rye will not control weedy grasses. 

for their pest-related benefits on cash crops Because it can increase numbers of cut worms 

and field environments. 

and wire worms in no-till planting conditions, 

Learn all you can about the impacts of a rye is not the most suitable cover where those 

cover crop species to help you manage it in worms are a problem ahead of grass crops like 

your situation. Here are several widely used corn, sweet corn, sorghum or pearl millet. 

cover crops described by their effects under • Wheat (Triticum aestivum)—A winter 

conservation tillage in relation to insects, annual grain, wheat is widely adapted and 

diseases, nematodes and weeds. 

works much like rye in controlling diseases, 

• Cereal Rye (Secale cereale)—This winter nematodes and broadleaf weeds.Wheat is not 

annual grain is perhaps the most versatile as effective as rye in controlling weeds 

cover crop used in the continental United because it produces less biomass and has less 

States. Properly managed under conservation allelopathic effect. 

tillage, rye has the ability to reduce soil-borne • Crimson Clover (Trifolium 

diseases, nematodes and weeds. Rye is a nonhost 

plant for root-knot nematodes and soil- 

annual legume throughout the Southeast, fall- 

incarnatum)—Used as a self-reseeding winter 

borne diseases. It produces significant biomass planted crimson clover supports and increases 

that smothers weeds when it is left on the soil-borne diseases, pythium-rhizoctonia 

surface and also controls weeds 

complex and root-knot nematodes. It 

allelopathically through natural weedsuppressing 

compounds. 

thick mulch. Crimson supports high densities 

suppresses weeds effectively by forming a 

As it grows, rye provides habitat, but not of beneficial insects by providing food and 

food, for beneficial insects. Thus, only a small habitat. Because some cultivars produce “hard 

number of beneficial insects are found on rye. seed” that resists immediate germination, 

Fall-planted rye works well in reducing soilborne 

diseases, root-knot nematodes and 

late spring so that it resumes its growth in late 

crimson clover can be managed to reseed in 

broadleaf weeds in all cash crops that follow, summer and fall. 

Soilborne pathogenic fungi limit production of 

vegetables and cotton in the southern U.S. (332, 

333, 334, 335). Rhizoctonia solani, Pythium 

myriotylum, Pythium phanidermatum and 

Pythium irregulare are the most virulent pathogenic 

fungi that cause damping-off on cucumbers 

and snap beans. Sclerotium rolfsii causes rot in 

all vegetables and in peanuts and cotton. Infected 

plants that do not die may be stunted because of 

lesions caused by fungi on primary or secondary 

roots,hypocotyls and stems.But after two or three 

years in cover cropped, no-till systems, dampingoff 

is not a serious problem, experience on south 

Georgia farms and research plots shows. Higher 

soil organic matter may help. 

In soils with high levels of disease inoculum, 

however, it takes time to reduce population levels 

of soil pathogens using only cover crops. 

After tests in Maine with oats, broccoli, white 

lupine (Lupinus albus) and field peas (Pisum 

sativum) as covers,researchers cautioned it may 

take three to five years to effectively reduce 

stem lesion losses on potatoes caused by R. 

solani (190).Yet there are single-season improvements, 

too. For example, in an Idaho study, 

Verticillium wilt of potato was reduced by 24 to 

29 percent following Sudangrass green manure. 

Yield of U.S.No.1 potatoes increased by 24 to 38 

percent compared with potatoes following 

barley or fallow (322). 


• Subterranean Clover (Trifolium 

subterraneum)—A self-reseeding annual 

legume, fall-planted subterranean clover carries 

the same risks as crimson clover with soilborne 

diseases and nematodes. It suppresses 

weeds more effectively in the deep South, 

however, because of its thick and low growth 

habit. Subclover supports a high level of 

beneficial insects. 

• Cahaba White Vetch (V. sativa X V. 

cordata)—This cool-season annual legume is a 

hybrid vetch that increases soilborne diseases 

yet suppresses root-knot nematodes. It 

supports beneficial insects, yet attracts very 

high numbers of the tarnished plant bug, a 

serious pest. 

• Buckwheat (Fagopyrum esculentum)— 

A summer annual non-legume, buckwheat is 

very effective in suppressing weeds when 

planted thickly. It also supports high densities 

of beneficial insects. It is suitable for sequential 

planting around non-crop areas to provide 

food and habitat for beneficial insects. It is 

very attractive to honeybees. 

A well-planned crop rotation maximizes 

benefits and compensates for the risks of 

cover crops and cash crops. Planting rye in a 

no-till system substantially reduces root-knot 

nematodes, soil-borne diseases and broadleaf 

weeds. By using clovers and vetches in your 

fields and adding beneficial habitat in noncultivated 

areas, you can increase populations 

of beneficial insects that help to keep insects 

pests under control. Mixed plantings of a small 

grains and legumes combine benefits of both 

while reducing their shortcomings. 

As pesticides of all types (fungicides, 

herbicides, nematicides and insecticides) are 

reduced, the field environment becomes 

increasingly resilient in keeping pest outbreaks 

in check. Plantings to further increase 

beneficial habitat in non-cultivated areas can 

help maintain pollinating insects and pest 

predators, but should be monitored to avoid 

build-ups of potential pests. Researchers are 

only beginning to understand how to manage 

these “insectary plantings.” 

Editor’s Note: Each cover crop listed here, 

except for cahaba vetch, is included in the 

charts (pp. 48 and following) and is fully 

described in its respective section. Check the 

Table of Contents (p. 6) for location. 

—Sharad C. Phatak 

Nematode Management 

Nematodes are minute roundworms that interact 

directly and indirectly with plants. Some species 

feed on roots and weaker plants, and also introduce 

disease through feeding wounds. Most 

nematodes are not plant parasites,but feed on and 

interact with many soil-borne microorganisms, 

including fungi, bacteria and protozoa. Damage 

from plant-parasitic nematodes results in a breakdown 

of plant tissue, such as lesions or yellow 

foliage; retarded growth of cells, seen as stunted 

growth or shoots; or excessive growth such as 

root galls, swollen root tips or unnatural root 

branching. 

If the community of nematodes contains 

diverse species, no single species will dominate. 

This coexistence would be the case in the undisturbed 

field or woodland described above. 

In conventional crop systems, pest nematodes 

have abundant food and little environmental resistance. 

This can lead to rapid expansion of plant 

parasitic species, plant disease and yield loss. 

Cropping systems that increase biological diversity 

over time usually prevent the onset of 

nematode problems. Reasons may include a 

dynamic soil ecological balance and improved, 

healthier soil structure with higher organic 

matter. In Michigan, some potato growers report 

that two years of alfalfa to limit nematodes 

between potato crops is sustainable for them 

because of improvements to potato production 

and lower pest control costs (20). 


Once a nematode species is established in a 

field, it is usually impossible to eliminate it. Some 

covers can enhance a resident parasitic nematode 

population if they are grown before or after 

another crop that hosts a plant-damaging nematode 

species. 

If a nematode pest species is absent from the 

soil, planting a susceptible cover crop will not 

give rise to a problem,assuming the species is not 

introduced on seed, transplants or machinery 

(296). One Iowa farmer reports that researchers 

analyzing his fields have found no evidence that 

hairy vetch,a host for soybean cyst nematode,has 

caused any problem with the pest in his soybeans. 

This may be due to his use compost in 

strip-cropped fields with an oats/hairy 

vetch>corn>soybean rotation (346). 

You can gradually reduce a field’s nematode 

pest population or limit nematode impact on 

crops by using specific cover crops. Nematode 

control tactics involving covers include: 

• Manipulating soil structure or soil humus 

• Rotating with non-host crops 

• Using crops with nematicidal effects, such as 

brassicas 

Cover crops may also improve overall plant 

vitality to lessen the nematode impact on yield. 

But if you suspect nematode trouble, send a soil 

sample for laboratory analysis to positively identify 

the nematode species.Then be sure any cover 

crops you try aren’t alternate hosts for that pest 

species. Area IPM specialists can help you. 

Using brassicas and many grasses as cover 

crops can help you manage nematodes. Cover 

crops with documented nematicidal properties 

against at least one nematode species include 

sorghum-sudangrass hybrids (Sorghum bicolor X 

S. bicolor var. sudanese), marigold (Tagetes 

patula), hairy indigo (Indigofera hirsuta), showy 

crotalaria (Crotolaria spectabilis), sunn hemp 

(Crotalaria juncea) and velvetbean (Mucuna 

deeringiana). 

You must match specific cover crop species 

with the particular nematode pest species, then 

manage it correctly. For example, cereal rye 

residue left on the surface or incorporated to a 

depth of several inches suppressed Columbia 

lance nematodes in North Carolina cotton fields 

better than if the cover was buried more deeply 

by moldboard plowing. Associated greenhouse 

tests in the study showed that incorporated rye 

was effective against root-knot,reniform and stubby 

root nematodes, as well (14). 

Malt barley, corn, radishes and mustard sometimes 

worked as well as the standard nematicide 

to control sugar beet nematode in Wyoming sugar 

beets,a 1994 study showed.Increased production 

more than offset the cover crop cost, and lamb 

grazing of the brassicas increased profit without 

diminishing nematode suppression. The success 

is conditional upon a limited nematode density. 

The cover crop treatment was effective only if 

there were fewer than 10 eggs or juveniles per 

cubic centimeter of soil. A moderate sugar beet 

nematode level was reduced 54 to 75 percent in 

about 11 weeks, increasing yield by nearly 4 tons 

per acre (184). 

Weed Management 

Cover crops are widely used as smother crops to 

shade and out-compete weeds. Cereal grains 

establish quickly as they use up the moisture, fertility 

and light that weeds need to survive. 

Sorghum-sudangrass hybrids and buckwheat are 

warm-season crops that suppress weeds through 

these physical means and by plant-produced 

natural herbicides (allelopathy). 

Cereal rye is an overwintering crop that suppresses 

weeds both physically and chemically. If 

rye residue is left on the soil surface, it releases 

allelochemicals that inhibit seedling growth of 

many annual small-seeded broadleaf weeds, such 

as pigweed and lambsquarters. The response of 

grassy weeds is more variable.Rye is a major component 

in the killed organic mulches used in notill 

vegetable transplanting systems. 

Killed cover crop mulches last longer if the 

stalks are left intact, providing weed control well 

into the season for summer vegetables. Two 

implements have been modified in recent years 

specifically to enhance weed suppression by 

cover crops. The undercutter uses a wide blade 

to slice just under the surface of raised beds, severing 

cover crop plants from their root mass.An 

attached rolling harrow increases effectiveness 

(69, 70, 71, 72). A Buffalo rolling stalk chopper 


does no direct tillage, but aggressively bends and 

cuts crops at the surface (132). Both tools work 

well on most legumes when they are in midbloom 

stage or beyond. 

Killed mulch of a cover crop mix of rye, hairy 

vetch, crimson clover and barley kept processing 

tomatoes nearly weed-free for six weeks in an 

Ohio test. This length of time is significant, 

because other research has shown that tomato 

fields kept weed-free for 36 days yield as much as 

fields kept weed-free all season (71, 115). 

Cover crops can also serve as a “living mulch” 

to manage weeds in vegetable production. Cover 

crops are left to grow between rows of the cash 

crop to suppress weeds by blocking light and 

out-competing weeds for nutrients and water. 

They may also provide organic matter,some nitrogen 

(if legumes), beneficial insect habitat, erosion 

prevention, wind protection and a tough sod to 

support field traffic. 

To avoid competition with the cash crop,living 

mulches can be chemically or mechanically 

suppressed. In the Southeast, some cool-season 

cover crops such as crimson clover die out naturally 

during summer crop growth and do not 

compete for water or nutrients. However, cover 

crops that regrow during spring and summer— 

such as subterranean clover, white clover and red 

clover—can compete strongly for water with 

spring-planted crops unless the covers are adequately 

suppressed. 

In New York, growing cover crops overseeded 

within three weeks of potato planting provided 

good weed suppression, using 70 percent less 

herbicide. Yield was the same as, or moderately 

reduced from, the standard herbicide control 

plots in the two-year study.Hairy vetch,woolypod 

vetch, oats, barley, red clover and an oats/hairy 

vetch mix were suppressed as needed with fluazifop 

and metribuzin (280). 

Cover crops often suppress weeds early, then 

prevent erosion or supply fertility later in the season. 

For example, shade-tolerant legumes such as 

red clover or sweetclover that are planted with 

spring grains grow rapidly after grain harvest to 

prevent weeds from dominating fields in late summer. 

Overseeding annual ryegrass or oats at soybean 

leaf yellowing provides a weed-suppressing 

cover crop before frost and a light mulch to suppress 

winter annuals, as well. 

Cover crops can play a pest-suppressing role 

on virtually any farm. As we find out more about 

the pest management benefits of cover crop systems, 

they will become even more attractive 

from both an economic and an environmental 

perspective. Traditional research will identify 

some new pieces of these biologically based 

systems. However, growers who understand how 

all the elements of their farm fit together will 

be the people who will really bring cover crops 

into the prominence they deserve in sustainable 

farming. 

CRIMSON CLOVER, a winter annual legume, grows rapidly in spring to fix high levels of nitrogen. 


CROP ROTATION WITH COVER CROPS 

Readers’ note: > indicates progression to 

another crop; / indicates a mixture of crops 

growing at the same time. 

One of the biggest challenges of cover 

cropping is to fit cover crops into your 

current rotations, or to develop new 

rotations that take full advantage of their benefits. 

This section will explore some of the systems 

used successfully by farmers in different regions 

of the U.S. One might be easily adapted to fit your 

existing crops, equipment and management. 

Other examples may point out ways that you can 

modify your rotation to make the addition of 

cover crops more profitable and practical. 

Whether you add covers to your existing rotations 

or totally revamp your farming system, it is 

crucial that you devote as much planning and 

attention to your cover crops as you do to your 

cash crops. Failure to do so can lead to failure of 

the cover crop and cause problems in other parts 

of your system. Also remember that there is likely 

no single cover crop that is right for your farm. 

Ultimately, rotating cover crops might be your 

best strategy. (See, for example, California 

Vegetable Crop Systems, p. 37). Like any other 

crop, pest pressures may build up if a cover crop 

is grown too often in the same field. 

Before you start: 

• Review Benefits Of Cover Crops (p. 9) and 

Selecting the Best Cover Crops For Your Farm 

(p. 12) 

• Decide which benefits are most important 

to you 

• Read the examples below, then consider how 

these cover crop rotations might be adapted 

to your particular conditions 

• Talk to your neighbors and the other “experts” 

in your area, including the contact people listed 

in Regional Experts (p. 173) 

• Start small on an easily accessible plot that 

you will see often 

Be an opportunist—and an optimist. If your 

cropping plans for a field are disrupted by weather 

or other conditions outside of your control,this 

may be the ideal window for establishing a cover 

crop. Consider using an early-maturing cash crop 

to allow for timely planting of the cover crop.The 

ideas in this book will help you see cover crop 

opportunities in what used to look like problems. 

COVER CROPS FOR CORN BELT GRAIN 

AND OILSEED PRODUCTION 

In addition to providing winter cover and building 

soil structure, nitrogen (N) management will 

probably be a major factor in your cover crop 

decisions for the corn>soybean rotation. A fallplanted 

grass or small grain will scavenge leftover 

N from the previous corn or soybean crop. 

Legumes are much less efficient at scavenging N, 

but will add N to the system for the following 

crop. Legume/grass mixtures are quite good at 

both. 

Corn>Soybean Systems 

Keep in mind that: corn is a heavy nitrogen feeder; 

soybeans benefit little, if at all, from cover crop 

N; and that you have a shorter time for spring 

legume growth before corn than before soybeans. 

Cover crop features: rye provides winter cover, 

scavenges N after corn, becomes a long-lasting (6- 

week) residue for your beans to suppress weeds 

and hold moisture; hairy vetch provides spring 

ground cover,abundant N and a moderate-term (3 

to 4 week) mulch for the next corn crop; field 

peas are similar to vetch, but residue breaks 

down faster; red clover is also similar, but produces 

slightly less N and has less vigorous spring 

regrowth; berseem clover grows quickly to provide 

several cuttings for high-N green manure, 

then winterkills. 

Here are some options to consider adapting to 

your system: 

Corn>Rye>Soybeans>Hairy Vetch. In Zone 7 

and warmer, you can grow a cover crop every 

year between your corn and full-season beans. 

Also, you can use wheat or another small grain to 


eplace the cover crop before beans, in a threecrop, 

two-year rotation (corn>wheat>doublecrop 

beans). In all cases, another legume or a 

grass/legume mixture can be used instead of a single 

species cover crop. Where it is adapted, you 

can use crimson clover or a crimson/grass mixture 

instead of vetch. 

In cooler areas, plant rye as soon as possible 

after corn harvest. If you need more time in the 

fall, try overseeding in rowed beans at drydown 

“yellow leaf”stage in early fall, or in early summer 

at the last cultivation of corn. Seeding options 

include aerial application where the service is 

economical, using a specialty high-body tractor 

with narrow tires,or attaching a broadcast seeder, 

air seeder or seed boxes to a 

cultivator. 

Kill the rye once it is about 

knee-high, or let it go a bit 

longer, killing it a couple of 

weeks before planting beans. 

Killing the rye with herbicides 

and no-tilling beans in narrow rows allows 

more time for cover crop growth, since you don’t 

have to work the ground. If soil moisture is low, 

consider killing the rye earlier. Follow the beans 

with hairy vetch or a vetch/small grain mixture. 

Legumes must be seeded at least 6 weeks before 

hard frost to ensure winter survival. Seed by 

drilling after soybean harvest, or by overseeding 

before leaf drop. Allow the vetch (or mixture) to 

grow as long as possible in spring for maximum N 

fixation. 

Worried about planting your corn a bit 

late because you’re waiting for your cover crop to 

mature Research in Maryland, Illinois and elsewhere 

suggests that planting corn towards the 

end of the usual window when using a legume 

cover crop has its rewards. The delay can result 

in greater yields than earlier planting, due to 

greater moisture conservation and more N produced 

by the cover crop, or due to the timing of 

summer drought (62, 64, 243, 338). Check your 

state variety trial data for a shorter season corn 

hybrid that yields nearly as well as slightly longer 

season corn.The cover crop benefit should overcome 

many yield differences. 

Growers are looking to add 

a small grain to their 

corn>soybean rotation. 

Worried about soil moisture There’s no 

question that growing cover crops may consume 

soil moisture needed by the next crop. In humid 

regions, this is a problem only in an unusually dry 

spring.Time permitting, allow 2 to 3 weeks after 

killing the cover crop to alleviate this problem. 

While spring rainfall may compensate for the 

moisture demand of most cover crops by normal 

planting dates, rye can quickly dry out a field. 

Later in the season, killed cover crop residues 

in minimum tillage systems can conserve 

moisture and increase yields. 

In dryland areas of the Southern Great Plains, 

lack of water limits cover crop use. (See Dryland 

Cereal Cropping Systems, p. 40). 

In any system where you 

are using accumulated soil 

moisture to grow your cash 

crop, you need to be extra 

careful. However, as noted in 

this section and elsewhere 

in the book, farmers and 

researchers are finding that water-thrifty cover 

crops may be able to replace even a fallow year 

without adversely affecting the cash crop. 

Corn>Rye>Soybeans>Small Grain>Hairy 

Vetch. This rotation is similar to the 

corn>rye>soybeans rotation described above, 

except you add a year of small grains following 

the beans. This is the standard rotation in the 

grain-growing regions of Paraguay and Brazil, 

where it is critical to maintain soil organic matter. 

In crop rotation research from different areas, 

many benefits accrue as the rotation becomes 

longer. This is because weed, disease and insect 

pest problems generally decrease with an 

increase in years between repeat plantings of the 

same crop. 

Residue from small grains provides good organic 

matter for soil building, and in the case of winter 

grains, the plants help to prevent erosion over 

winter after soybeans loosen up the soil. If seeding 

with small grains, select cover crops that will 

stand shade and some traffic. 

The length of the growing season will determine 

how you fit in cover crops after full-season 

CROP ROTATION WITH COVER CROPS 35

soybeans in the rotation. Consider using a shortseason 

bean if needed in order to achieve timely 

planting after soybean harvest.Calculate whether 

cover crop benefits will compensate for a possible 

yield loss on the shorter season beans.If there 

is not enough time to seed a legume after harvest, 

use a small grain rather than no cover crop 

at all. 

The small grain scavenges leftover N following 

beans. Legume cover crops reduce fertilizer N 

needed for following corn, a heavy N feeder. If 

you cannot seed the legume at least six weeks 

before a hard frost, consider overseeding before 

leaf drop or at last cultivation. 

An alternate rotation for the lower mid-South 

is corn>crimson clover (allowed to go to seed) 

> soybeans > crimson clover (reseeded) > corn. 

Allow the crimson clover to go to seed before 

planting beans. The clover germinates in late summer 

under the beans. Kill the cover crop before 

corn the next spring. If possible, choose a different 

cover crop following the corn this time to 

avoid potential pest and disease problems with 

the crimson clover. 

▲ Precaution. In selecting a cover crop to 

interseed, do not jeopardize your cash crop if soil 

moisture is usually limiting during the rest of the 

corn season! Banding cover crop seed in row 

middles by using insecticide boxes or other 

devices can reduce cover crop competition with 

the cash crop. 

3 Year: Corn>Soybean>Wheat/Red Clover. 

This well-tested Wisconsin sequence provides N 

for corn as well as general rotation effects in weed 

suppression and natural controls of disease and 

insect pests. It was more profitable in recent 

years as the cost of synthetic N increased. Corn 

benefits from legume-fixed N, and from the 

improved cation exchange capacity in the soil 

that comes with increasing organic matter levels. 

With the changes in base acreage requirements 

in the 1996 Farm Bill, growers in the upper 

Midwest are looking to add a small grain to their 

corn>bean rotation.The small grain, seeded after 

soybeans,can be used as a cover crop,or it can be 

grown to maturity for grain.When growing wheat 

or oats for grain, frost-seed red clover or sweetclover 

in March, harvest the grain, then let the 

clover grow until it goes dormant in late fall. 

Follow with corn the next spring. Some secondary 

tillage can be done in the fall,if conditions 

allow.One option is to attach sweeps to your chisel 

plow and run them about 2 inches deep, cutting 

the clover crowns (326). 

Alternatively, grow the small grain to maturity, 

harvest, then immediately plant a legume cover 

crop such as hairy vetch or red clover in August or 

early September. Soil moisture is critical for quick 

germination and good growth before frost. For 

much of the northern U.S., there is not time to 

plant a legume after soybean harvest,unless it can 

be seeded aerially or at the last cultivation. If 

growing spring grains, seed red clover or sweetclover 

directly with the small grain. 

Adding the small grain to the rotation helps 

control white mold on soybeans, since two years 

out of beans are needed to reduce pathogen populations. 

Using a grain/legume mix will scavenge 

available N from the bean crop, hold soil over 

winter and begin fixing N for the corn. Clovers or 

vetch can be harvested for seed,and red or yellow 

clover can be left for the second year as a green 

manure crop. 

Using a spring seeding of oats and berseem 

clover has proved effective on Iowa farms that 

also have livestock. The mix tends to favor oat 

grain production in dry years and berseem production 

in wetter years. Either way the mixture 

provides biomass to increase organic matter and 

build soil. The berseem can be clipped several 

times for green manure. 

▲ Precaution. Planting hairy vetch with small 

grains may make it difficult to harvest a clean 

grain crop. Instead, seed vetch after small grain 

harvest. 

COVER CROPS FOR VEGETABLE PRODUCTION 

Vegetable systems often have many windows for 

including cover crops. Periods of one to two 

months between harvest of early planted spring 

crops and planting of fall crops can be filled 

using fast-growing warm-season cover crops such 


as buckwheat, cowpeas, sorghum-sudangrass 

hybrid, or another crop adapted to your conditions. 

As with other cropping systems, plant a 

winter annual cover crop on fields that otherwise 

would lie fallow. 

Where moisture is sufficient, many vegetable 

crops can be overseeded with a cover crop, which 

will then be established and growing after vegetable 

harvest. Select cover crops that tolerate shade and 

harvest traffic, especially where there will be multiple 

pickings,such as in tomatoes or peppers. 

Cover crop features: Oats add lots of biomass, 

are a good nurse crop for spring-seeded legumes, 

and winterkill, doing away with the need for 

spring killing and tilling. Sorghum-sudangrass 

hybrid produces deep roots and tall, leafy stalks 

that die with the first frost. Yellow sweetclover 

is a deep rooting legume that provides cuttings of 

green manure in its second year. White clover is 

a persistent perennial and 

good N source. 

In Zone 5 and cooler, 

plant rye, oats or a summer 

annual (in August) after snap 

bean or sweet corn harvest 

for organic matter production 

and erosion control, 

especially on sandy soils. Incorporate the following 

spring, or leave untilled strips for continued 

control of wind erosion. 

If you have the option of a full year of cover 

crops in the East or Midwest, plant hairy vetch in 

the spring, allow to grow all year, and it will die 

back in the fall. Come back with no-till sweet or 

field corn or another N-demanding crop the 

following spring. Or, hairy vetch planted after 

about August 1 will overwinter in most zones 

with adequate snow coverage. Allow it to grow 

until early flower the following spring to achieve 

full N value. Kill for use as an organic mulch for 

no-till transplants or incorporate and plant a 

summer crop. 

You can sow annual ryegrass right after harvesting 

an early-spring vegetable crop, allow it to 

grow for a month or two, then kill, incorporate 

and plant a fall vegetable. 

Residue from small grains 

provides organic matter for 

soil building. . . to prevent 

erosion over winter. 

Some farmers maximize the complementary 

weed-suppressing effects of various cover crop 

species by orchestrating peak growth periods, 

rooting depth and shape, topgrowth differences 

and species mixes. See Full-Year Covers Tackle 

Tough Weeds (p. 38). 

3 Year: Winter Wheat/Legume Interseed> 

Legume>Potatoes. This eastern Idaho rotation 

conditions soil, helps fight soil disease and 

provides N. Sufficient N for standard potatoes 

depends on rainfall being average or lower to 

prevent leaching that would put the soil N below 

the shallow-rooted cash crop. 

1 Year: Lettuce>Buckwheat>Buckwheat> 

Broccoli>White Clover/Annual Ryegrass.The 

Northeast’s early spring vegetable crops often 

leave little residue after their early summer harvest. 

Sequential buckwheat plantings suppress 

weeds, loosen topsoil and 

attract beneficial insects. 

Buckwheat is easy to kill by 

mowing in preparation for fall 

transplants. With light tillage 

to incorporate the relatively 

small amount of fast-degrading 

buckwheat residue, you 

can then sow a winter grass/legume cover mix to 

hold soil throughout the fall and over winter. 

Planted at least 40 days before frost, the white 

clover should overwinter and provide green 

manure or a living mulch the next year. 

California Vegetable Crop Systems 

Innovative work in California includes rotating 

cover crops as well as cash crops, adding diversity 

to the system.This was done in response to an 

increase in Alternaria blight in LANA vetch if 

planted year after year. 

4 Year: LANA Vetch>Corn>Oats/Vetch>Dry 

Beans>Common Vetch>Tomatoes>S-S Hybrid/ 

Cowpea>Safflower. The N needs of the cash 

crops of sweet corn,dry beans,safflower and canning 

tomatoes determine,in part,which covers to 

grow. Corn, with the highest N demand, is pre- 


Full-Year Covers Tackle Tough Weeds 

TROUT RUN, Pa.—Growing cover crops for a 

full year between cash crops helps Eric and 

Anne Nordell control virtually every type of 

weed nature throws at their vegetable farm— 

even quackgrass. 

The couple experimented with many 

different cover crops on their north-central 

Pennsylvania farm before adapting a system 

used to successfully battle quackgrass 

on a commercial herb farm in the Pacific 

Northwest. Between cash crops, the Nordells 

grow two winter cover crops to smother 

weeds.A brief stint of aggressive summer 

tillage between the two cover crops keeps 

annual weeds from setting seed. 

Regular use of cover crops in their halfacre 

strips between rows of vegetables also 

improves soil quality and moisture retention 

while reducing erosion.“Vegetable crops 

return very little to the soil as far as a root 

system,” says Eric, a frequent speaker on 

conservation practices at conferences in the 

Northeast.“You cut a head of lettuce and have 

nothing left behind. Growing vegetables, we’re 

always trying to rebuild the soil.” 

The Nordells’ short growing season— 

which typically ends with the first frost in 

September—makes it challenging to squeeze 

in cover crops on their six cultivated acres. 

Yellow blossom sweetclover is overseeded 

at 20 to 24 lb./A into early crops such as 

onions or spring lettuce. Lettuce is overseeded 

a week or two after planting but before leaves 

open up to trap sweetclover seeds, while 

onions are overseeded near harvest.The 

Nordells walk up and down every other row 

with a manual Cyclone seeder (canvas bag 

with a hand-crank spinner).They harvest the 

cash crop, then let the clover grow through 

summer. 

Yellow blossom sweetclover—one of the 

best cover crop choices for warm-season 

nitrogen production—puts down a deep 

taproot before winter if seeded in June or 

July, observes Eric.“That root system loosens 

the soil, fixes nitrogen, and may even bring 

up minerals from the subsoil with its long 

tap root.” He points out that the clover alone 

would not suppress weeds.The sole-seeding 

works on their farm because of their 

successful management efforts over a 

decade to suppress overall weed pressure 

by crop rotation and varied cover crops. 

In spring, the sweetclover grows until it 

is about knee-high in mid-May. Then the 

Nordells clip it just before it buds.They let 

the regrowth bloom to attract pollinators 

and beneficial insects to the field, before 

clipping it again in July. 

In early- to mid-July, the Nordells moldboard 

plow the sweetclover to kill it.They leave the 

ground in bare fallow, working it again with a 

springtooth harrow to hit perennial weeds at 

the weakest point of their lifecycle. After that, 

ceded by LANA vetch, which produces more N than 

other covers. Before tomatoes, common vetch works 

best. A mixture of purple vetch and oats is grown 

before dry beans, and a mix of sorghum-sudangrass 

and cowpeas precedes safflower. 

In order to get maximum biomass and N 

production by April 1,LANA vetch is best planted early 

enough (6 to 8 weeks before frost) to have good 

growth before “winter.”Disked in early April,LANA provides 

all but about 40 lb.N/A to the sweet corn crop. 

Common vetch, seeded after the corn, can fix most 

of the N required by the subsequent tomato crop, 

with about 30 to 40 lb.N/A added as starter. 

A mixture of sorghum-sudangrass and cowpeas is 

planted following tomato harvest. The mixture 

responds to residual N levels with N-scavenging by 

the grass component to prevent winter leaching. 

The cowpeas fix enough N for early growth of the 

subsequent safflower cash crop, which has relatively 

low initial N demands. The cover crop breaks 

down fast enough to supply safflower’s later-season 

N demand. 


the couple harrows every two to three weeks 

to bring weed roots and rhizomes to the soil 

surface, where they bake in the summer sun. 

The harrowing also kills flushes of annual 

weeds before they can set seed. 

After five years in this weed-killing 

rotation, the Nordells were able to cut back 

on harrowing, which they now coordinate 

with rainfall and weed pressure. In the 

unusually dry summer of 1997, for example, 

they did not harrow at all after plowing. 

In mid-August, the Nordells plant a second, 

overwintering cover crop. In this rotation, 

they seed a mix of rye and hairy vetch.They 

broadcast and lightly incorporate about 80 

pounds rye and 30 pounds vetch per acre. 

The rye establishes quickly, putting on good 

growth both above and below the surface, 

while the vetch fixes nitrogen.Another 

combination is yellow, red and white clover in 

a 2:2:1 ratio by volume.“We’re looking for a 

green field by Labor Day,” Eric says.“We want 

a good sod before we get our first freeze.” 

Rye and vetch are a popular combination 

to manage nitrogen.The rye takes up excess 

N from the soil, preventing leaching.The 

vetch fixes additional nitrogen which it 

releases after it’s killed the following spring 

prior to planting the next cash crop. 

With the August seeding, the Nordells’ 

rye/vetch mixture produces most of its 

biomass in fall. 

The Nordells plow the rye/vetch mix 

after it greens up in late March to early April, 

working shallowly so as not to turn up as 

many weed seeds.They forego maximum 

biomass and N for earlier planting of their 

cash crop—tomatoes, peppers, summer 

broccoli or leeks—around the end of May. 

The bare fallow during mid-summer plus 

early spring incorporation of overwintering 

cover crops are the best preventive to slugs 

and grubs, they have found. 

Thanks to their weed-suppressing cover 

crops, the Nordells typically spend less than 

10 hours a season hand-weeding their three 

acres of cash crops, and never need to hire 

outside weeding help.“Don’t overlook the 

cover crops’ role in improving soil tilth and 

making cultivation easier,” adds Eric. Before 

cover cropping, he noticed that their silty 

soils deteriorated whenever they grew two 

cash crops in a row.“When the soil structure 

declines, it doesn’t hold moisture and we 

get a buildup of annual weeds,” he notes. 

The Nordells can afford to forego a cash 

crop to keep half their land in cover crops 

because their tax bills and land value are not 

as high as market gardeners in a more urban 

setting.“We take some land out of production, 

but in our situation, we have the land,” Eric 

says.“If we had to hire people for weed 

control, it would be more costly.” 

See Recommended Resources (p. 162) to 

order a video describing this system. 

▲ Precaution. If you are not using any herbicides, 

vetch could become a problem in the 

California system.Earlier kill sacrifices N,but does 

not allow for the production of hard seed that 

stays viable for several seasons. 

COVER CROPS FOR COTTON PRODUCTION 

In what would otherwise be continuous cotton 

production, any winter annual cover crop added 

to the system can add rotation benefits, help 

maintain soil productivity, and provide the many 

other benefits of cover crops highlighted 

throughout this book. 

Hairy vetch, crimson clover, or mixtures with 

rye or another small grain can reduce erosion,add 

N and organic matter to the system. Drill after 

shredding stalks in the fall and kill by spraying or 

mowing prior to no-till seeding of cotton in May. 

Or, aerially seed just before application of 

defoliant. The dropping leaves mulch the cover 

crop seed, aiding germination. Rye works better 


than wheat.Yields are usually equal to, or greater 

than yields in conventional tillage systems with 

winter fallow. 

Balansa clover, a promising cover crop for the 

South, reseeds well in no-till cotton systems (see 

Up-and-Coming Cover Crops, p. 158). 

1 Year: Rye/Legume>Cotton. Plant the rye/ 

legume mix in early October, or early enough to 

allow the legume to establish well before cooler 

winter temperatures. Kill by late April, and if soil 

moisture permits, no-till plant cotton within three 

to five days using tined-wheel row cleaner attachments 

to clear residue. Band-spray normal preemergent 

herbicides over the cleaned and planted 

row area.Cotton will need additional weed control 

toward layby using flaming, cultivation or directed 

herbicides. Crimson clover, hairy vetch, Cahaba 

vetch and Austrian winter peas are effective 

legumes in this system. 

Multiyear: Reseeding Legume>No-Till Cotton> 

Legume>No-Till Cotton. Subterranean clover, 

Southern spotted burclover, PARADANA balansa 

clover and some crimson clover cultivars set seed 

quickly enough in some areas to become perpetually 

reseeding when cotton planting dates are 

late enough in spring.Germination of hard seed in 

late summer provides soil erosion protection over 

winter, N for the following crop and an organic 

mulch at planting. 

Strip planting into reseeding legumes works for 

many crops in the South, including cotton, corn, 

sweet potatoes, peanuts, peppers, cucumbers, 

cabbage and snap beans. Tillage or herbicides 

are used to create strips 12 to 30 inches wide. 

Wider killed strips reduce moisture competition 

by the cover crop before it dies back naturally,but 

also reduce the amount of seed set, biomass and 

N produced. Wider strips also decrease the 

mulching effect from the cover crop residue. 

The remaining strips of living cover crop act as 

in-field insectary areas to increase overall insect 

populations, resulting in more beneficial insects 

to control pest insects. 

▲ Precautions 

• Watch for moisture depletion if spring is 

unusually dry. 

• Be sure to plant cotton by soil temperature 

(65 F is required), because cover crops may 

keep soil cool in the spring. Don’t plant too 

early! 

• A delay of two to three weeks between cover 

crop kill and cotton planting reduces these 

problems, and reduces the chance of stand 

losses due to insects (cutworm), diseases or 

allelopathic chemicals. 

• Additional mid-summer weed protection is 

needed during the hot-season “down time” for 

the reseeding legumes. 

DRYLAND CEREAL-LEGUME 

CROPPING SYSTEMS 

Soil moisture availability and use by cover crops 

are the dominant concerns in dryland production 

systems. Yet more and more innovators are find- 

ANNUAL and PERENNIAL MEDIC cultivars can fix N on low moisture, and can reduce erosion in dryland areas 

compared with bare fallow between crop seasons. 


Start Where You Are 

In many instances, you can begin using cover 

crops without substantially altering your cash 

crop mix or planting times or buying new 

machinery. Later, you might want to change 

your rotation or other practices to take better 

advantage of cover crop benefits. 

We’ll use a basic Corn Belt situation as a 

model. From a corn>soybean rotation, you 

can expand to: 

Corn>Cover>Soybean>Cover. Most popular 

choices are rye or rye/vetch mixture following 

corn; vetch or rye/vetch mixture following 

beans. Broadcast or drill covers immediately 

after harvest. Hairy vetch needs at least 15 

days before frost in 60 F soil. Rye will germinate 

as long as soil is just above freezing. Drill 

for quicker germination. Consider overseeding 

at leaf-yellowing if your post-harvest planting 

window is too short. 

If you want to make certain the legume is 

well established for maximum spring N and 

biomass production, consider adding a small 

grain to your rotation. 

Corn>Soybean>Small Grain/Cover. Small 

grains could be oats, wheat or barley. Cover 

could be vetch, field peas or red clover. If you 

want the legume to winterkill to eliminate 

spring cover crop killing, try a non-hardy cultivar 

of berseem clover or annual alfalfa. 

If you have livestock, a forage/hay market 

option or want more soil benefits, choose a 

longer-lived legume cover. 

Corn>Soybean>Small Grain/Legume> 

Legume Hay, Pasture Or Green Manure. 

Yellow sweetclover or red clover are popular 

forage choices. An oats/berseem interseeding 

provides a forage option the first year. 

Harvesting the cover crop or incorporating 

it early in its second season opens up new 

options for cash crops or a second cover crop. 

Late-season tomatoes, peppers, vine crops 

or sweet corn all thrive in the warm, enriched 

soil following a green manure. Two heat-loving 

covers that could be planted after killing a coolseason 

legume green manure are buckwheat 

(used to smother weeds, attract beneficial 

insects or for grain harvest) and sorghum- 

Sudangrass hybrid (for quick plow-down 

biomass or to fracture compacted subsoil). 

These crops would work most places in the 

Corn Belt. To get started in your area, check 

Top Regional Cover Crop Species (p. 47) 

to fill various roles, or Cultural Traits and 

Planting (p. 50) to find which cover crops 

fit best in your system. 

ing that carefully managed and selected cover 

crops in their rotations result in increased soil 

moisture availability to their cash crops.This delicate 

balance between water use by the cover 

crop and water conservation will dictate, in part, 

how cover crops work in your rotation. 

Cover crop features: perennial medics persist 

due to hard seed,providing green manure and 

erosion control; field peas and lentils (grain 

legumes) are shallow-rooted yet produce crops 

and additional N in years of good rainfall. 

An excellent resource describing these rotations 

in detail is Cereal-Legume Cropping 

Systems: Nine Farm Case Studies in the Dryland 

Northern Plains, Canadian Prairies and 

Intermountain Northwest. See Appendix C, 


In an area of Montana receiving 11 to 12 inches 

of rainfall per year, where summer fallow is the 

norm, some farmers and ranchers are using cover 

crops and longer rotations to eliminate fallow. 

Greg Gould believes he can do without summer 

fallow because his rotation has improved his soil’s 

water-holding capacity. While most farmers in his 

area think water is the limiting factor, he thinks it 

is the condition of the soil. 


7 to 13 Years: Flax>Winter Wheat>Spring 

Barley>Buckwheat>Spring Wheat>Winter 

Wheat>Alfalfa (up to 6 years) >Fallow 

System sequences are: 

• Flax or other spring crops (buckwheat, wheat, 

barley) are followed by fall-seeded wheat 

(sometimes rye), harvested in July, leaving 

stubble over the winter; 

• Spring-seeded barley or oats, harvested in 

August, leaving stubble over the winter; 

• Buckwheat, seeded in June and harvested in 

October, helps to control the weeds that have 

begun cropping up; 

• A spring small grain, which outcompetes any 

volunteer buckwheat (alternately, fall-seeded 

wheat, or fall-seeded sweetclover for seed or 

hay). 

The rotation closes with up to 6 years of alfalfa, 

plowdown of sweetclover seeded with the previous 

year’s wheat or an annual legume green 

manure such as Austrian winter peas or berseem 

clover. 

There are many points during this rotation where 

a different cash crop or cover crop can be substituted, 

particularly in response to market conditions. 

Furthermore, with Angus cattle on the ranch, many 

of the crops can be grazed or cut for hay. 

Moving into areas with more than 12 inches of 

rain a year opens additional windows for incorporating 

cover crops into dryland systems. 

9 Year: Winter Wheat>Spring Wheat>Spring 

Grain/Legume Interseed>Legume Green 

Manure/Fallow>Winter Wheat>Spring 

Wheat>Grain/Legume Interseed>Legume> 

Legume. In this rotation, one year of winter 

wheat and two years of spring-seeded crops follow 

a two or three-year legume break. Each 

legume sequence ends with an early summer 

incorporation of the legume to save moisture followed 

by minimal surface tillage to control 

weeds. Deep-rooted winter wheat follows sweetclover, 

which can leave topsoil fairly dry. Springseeded 

grains prevent weeds that show up with 

successive winter grain cycles and have shallower 

roots that allow soil moisture to build up deeper 

in the profile. 

In the second spring-grain year, using a low-N 

demanding crop such as kamut wheat reduces 

the risk of N-deficiency. Sweetclover seeded with 

the kamut provides regrowth the next spring that 

helps to take up enough soil water to prevent 

saline seep. Black medic, INDIANHEAD lentils and 

SIRIUS field peas are water-efficient substitutes for 

the deep-rooted—and water hungry—alfalfa and 

sweetclover. These peas and lentils are springsown, 

providing back-up N production if the forage 

legumes fail to establish. 

While moisture levels fluctuate critically from 

year to year in dryland systems,N levels tend to be 

more stable than in the hot, humid South, and 

adding crop residue builds up soil organic matter 

more easily. Low-water use cover crops have 

been shown to use equal or less soil water than 

bare fallow treatment, while adding organic matter 

and N. Consequently, dryland rotations can 

have a significant impact on soils and the field 

environment when used over a number of years. 

When starting with dryland soil that has raised 

the same crop for many years with conventional 

inputs, it will take three to five years of soil-building 

rotations until soils become biologically 

active. This is the length of time often cited by 

farmers in many regions for soil-based changes to 

take place. These improved soils have higher 

organic matter, a crumbly structure, and good 

water retention and infiltration. They also resist 

compaction and effectively cycle nutrients from 

residue to following crops. 

Remember, the benefits of cover crops accrue 

over several years.You will see improvements in 

crop yield, pest management and soil tilth if you 

commit to cover crop use whenever and wherever 

possible in your rotations. 


INTRODUCTION TO CHARTS 

The four comprehensive charts that follow 

can help orient you to the major cover 

crops most appropriate to your needs and 

region.Bear in mind that choice of cultivar,weather 

extremes and other factors may affect a cover 

crop’s performance in a given year. 

CHART 1: TOP REGIONAL COVER CROP 

SPECIES 

This chart lists up to five cover crop recommendations 

per broad bioregion for six different 

major purposes: N Source, Soil Builder, Erosion 

Fighter, Subsoil Loosener, Weed Fighter and Pest 

Fighter. If you know your main goal for a cover 

crop, Chart 1 can suggest which cover crop 

entries to examine in the charts that follow and 

help you determine which major cover narrative(s) 

to read first. 

Disclaimer. The crops recommended here will 

not be the most successful in all cases within a 

bioregion, and others my work better in some 

locations and in some years. The listed cover 

crops are, however, thought by reviewers to have 

the best chance of success in most years under 

current management regimes. 

CHART 2: PERFORMANCE AND ROLES 

This chart provides relative ratings (with the 

exception of two columns having quantitative 

ranges) of what the top covers do best, such as 

supply or scavenge nitrogen, build soil or fight 

erosion. 

Seasonality has a bearing on some of these ratings.A 

cover that grows best in spring could suppress 

weeds better than in fall. Unless otherwise 

footnoted,however,the chart would rate a cover’s 

performance (relative to the other covers) for the 

entire time period it is likely to be in the field. 

Ratings are general for the species, based on measured 

results and observations over a range of 

conditions. The individual narratives provide 

more seasonal details.The added effect of a nurse 

crop is included in the “Weed Fighter” ratings for 

legumes usually planted with a grain or grass 

nurse crop. 

Column headings 

Legume N Source. Rates legume cover crops for 

their relative ability to supply fixed N. 

(Nonlegumes have not been rated for their biomass 

nitrogen content,so this column is left blank 

for nonlegumes.) 

Total N. A quantitative estimate of the reasonably 

expected range of total N provided by a 

legume stand (from all biomass,above- and below 

ground) in lb. N/A, based mostly on published 

research.This is total N, not the fertilizer replacement 

value. Nonlegumes have not been rated for 

their biomass nitrogen content, so this column is 

left blank for nonlegumes. Mature nonlegume 

residues also tend to immobilize N. 

Dry Matter. A quantitative estimate of the 

range of dry matter in lb./A/yr., based largely on 

published research.As some of this data is based 

on research plots, irrigated systems or multicut 

systems, your on-farm result probably would be 

in the low to midpoint of the dry matter range 

cited.This estimate is based on fully dry material. 

“Dry” alfalfa hay is often about 20 percent 

moisture, so a ton of hay would only be 1,600 lb. 

of “dry matter.” 

N Scavenger. Rates a cover crop’s ability to take 

up and store excess nitrogen. Bear in mind that 

the sooner you plant a cover after main crop 

harvest—or overseed a cover into the standing 

crop—the more N it will be able to absorb. 

Soil Builder. Rates a cover crop’s ability to produce 

organic matter and improve soil structure. 

The ratings assume that you plan to use cover 

crops regularly in your cropping system to provide 

ongoing additions to soil organic matter. 

CHARTS 43

Erosion Fighter. Rates how extensive and how 

quickly a root system develops, how well it holds 

soil against sheet and wind erosion and the influence 

the growth habit may have on fighting wind 

erosion. 

Weed Fighter. Rates how well the cover crop 

outcompetes weeds by any means through its life 

cycle, including killed residue. Note that ratings 

for the legumes assume they are established with 

a small-grain nurse crop. 

Good Grazing. Rates relative production, nutritional 

quality and palatability of the cover as a forage. 

Quick Growth. Rates the speed of establishment 

and growth. 

Lasting Residue. Rates the effectiveness of the 

cover crop in providing a long-lasting mulch. 

Duration. Rates how well the stand can provide 

long-season growth. 

Harvest Value. Rates the cover crop’s economic 

value as a forage (F) or as a seed or grain crop (S), 

bearing in mind the relative market value and 

probable yields. 

Cash Crop Interseed. Rates whether the cover 

crop would hinder or help while serving as a 

companion crop. 

CHART 3A: CULTURAL TRAITS 

This chart shows a cover crop’s characteristics 

such as life cycle, drought tolerance, preferred 

soils and growth habits. The ratings are general 

for the species, based on measured results and 

observations over a range of conditions.Choice of 

cultivar, weather extremes and other factors may 

affect a cover crop’s performance in a given year. 

Column headings 

Aliases. Provides a few common references for 

the cover crop. 

Type. Describes the general life cycle of the crop. 

B = Biennial. Grows vegetatively during its first 

year and, if it successfully overwinters, sets seed 

during its second year. 

CSA = Cool-Season Annual. Prefers cool temperatures 

and depending on which Hardiness 

Zone it is grown in, could serve as a fall, winter 

or spring cover crop. 

SA = Summer Annual. Germinates and 

matures without a cold snap and usually tolerates 

warm temperatures. 

WA = Winter Annual. Would be more cold-tolerant 

and would require freezing temperature or 

a cold period to set seed. 

LP = Long-lived Perennial. Can endure for 

many growing seasons. 

SP = Short-lived Perennial. Usually does not 

persist more than a few years, if that long. 

Hardy Through Zone. Refers to the standard 

USDA Hardiness Zones. See map on inside front 

cover. Bear in mind that regional microclimate, 

weather variations, and other near-term management 

factors such as planting date and companion 

species can influence plant performance 

expectations. 

Tolerances. How well a crop is likely to endure 

despite stress from heat, drought, shade, flooding 

or low fertility.The best rating would mean that 

the crop is expected to be fully tolerant. 

Habit. How plants develop. 

C = Climbing 

U = Upright 

P = Prostrate 

SP = Semi-Prostrate 

SU = Semi-Upright 


pH Preferred. The pH range in which a species 

can be expected to perform reasonably well. 

Best Established. The season in which a cover 

crop is best suited for planting and early growth. 

Note that this can vary by region and that it’s 

important to ascertain local planting date recommendations 

for specific cover crops. 

Season: F = Fall ; Sp = Spring; Su = Summer; 

W = Winter 

Time: E = Early; L = Late; M = Mid 

Minimum Germination Temperature. The 

minimum soil temperature (F) generally required 

for successful germination and establishment. 

CHART 3B: PLANTING 

Depth. The recommended range of seeding 

depth (in inches),to avoid either overexposure or 

burying too deeply. 

Rate. Recommended seeding rate for drilling and 

broadcasting a pure stand in lb./A, bu/A. and 

oz./100 sq.ft., assuming legal standards for germination 

percentage. Seeding rate will depend on 

the cover crop’s primary purpose and other factors. 

See the narratives for more detail about 

establishing a given cover crop. Pre-inoculated 

(“rhizo-coated”) legume seed weighs about onethird 

more than raw seed. Increase seeding rate 

by one-third to plant the same amount of seed per 

area. 

Cost. Material costs (seed cost only) in dollars per 

pound, based usually on a 50-lb. bag as of fall 

1997. Individual species vary markedly with supply 

and demand. Always confirm seed price and 

availability before ordering, and before planning 

to use less common seed types. 

Cost/A. Seed cost per acre based on the midpoint 

between the high and low of reported seed prices 

as of fall 1997 and the midpoint recommended 

seeding rate for drilling and broadcasting. Your 

cost will depend on actual seed cost and seeding 

rate. Estimate excludes associated costs such as 

labor, fuel and equipment. 

Inoculant Type. The recommended inoculant 

for each legume. Your seed supplier may only 

carry one or two common inoculants. You may 

need to order inoculant in advance. See Seed 

Suppliers, p. 166. 

Reseeds. Rates the likelihood of a cover crop reestablishing 

through self-reseeding if it’s allowed 

to mature and set seed.Aggressive tillage will bury 

seed and reduce germination. Ratings assume the 

tillage system has minimal effect on reseeding. 

Dependable reseeding ability is valued in some 

orchard, dryland grain and cotton systems, but 

can cause weed problems in other systems. See 

the narratives for more detail. 

CHARTS 4A AND 4B 

These charts provide relative ratings of other 

management considerations—benefits and possible 

drawbacks—that could affect your selection 

of cover crop species. 

The till-kill rating assumes tillage at an appropriate 

stage. The mow-kill ratings assume mowing 

at flowering,but before seedheads start maturing. 

See sectional narratives for details. 

Ratings are based largely on a combination of 

published research and observations of farmers 

who have grown specific covers.Your experience 

with a given cover could be influenced by sitespecific 

factors, such as your soil condition, crop 

rotation, proximity to other farms, weather 

extremes, etc. 

CHART 4A: POTENTIAL ADVANTAGES 

Soil Impact. Assesses a cover’s relative ability to 

loosen subsoil, make soil P and K more readily 

available to crops, or improve topsoil. 

Soil Ecology. Rates a cover’s ability to fight 

pests by suppressing or limiting damage from 

CHARTS 45

nematodes, soil disease from fungal or bacterial 

infection, or weeds by natural herbicidal 

(allelopathic) or competition/smothering action. 

Researchers report difficulty in conclusively 

documenting allelopathic activity distinct from 

other cover crop effects, and nematicidal impacts 

are variable, studies show.These are general, tentative 

ratings in these emerging aspects of cover 

crop influence. 

Other. Indicates likelihood of attracting beneficial 

insects,of accommodating field traffic (foot or 

vehicle) and of fitting growing windows or short 

duration. 

CHART 4B: POTENTIAL DISADVANTAGES 

Increase Pest Risks. Relative likelihood of a 

cover crop becoming a weed,or contributing to a 

likely pest risk. Overall, growing a cover crop 

rarely causes pest problems. But certain cover 

crops occasionally may contribute to particular 

pest, disease or nematode problems in localized 

areas, for example by serving as an alternate host 

to the pest. See the narratives for more detail. 

▲ Readers note the shift in meaning for symbols 

on this chart only. 

Management Challenges. Relative ease or difficulty 

of establishing, killing or incorporating a 

stand.“Till-kill”refers to killing by plowing,disking 

or other tillage. “Mature incorporation” rates the 

difficulty of incorporating a relatively mature 

stand.Incorporation will be easier when a stand is 

killed before maturity or after some time elapses 

between killing and incorporating. 


Chart 1 

TOP REGIONAL COVER CROP SPECIES 1 

Soil Erosion Subsoil Weed Pest 

Bioregion N Source Builder Fighter Loosener Fighter Fighter 

Northeast red cl, hairy v, ryegrs, swt cl, rye, ryegrs, sorghyb, sorghyb, rye, 

berseem, sorghyb, wht cl, swt cl ryegrs, rye, sorghyb 

swt cl rye oats buckwheat 

Mid-Atlantic hairy v, red cl, ryegrs, rye, wht cl, sorghyb, rye, ryegrs, rye, 

berseem, swt cl, cowpeas, swt cl oats, sorghyb 

crim cl sorghyb rye, ryegrs buckwheat 

Mid-South hairy v, sub cl, ryegrs, rye, wht cl, sorghyb, buckwheat, rye, 

berseem, sub cl, cowpeas, swt cl ryegrs, sub cl, sorghyb 

crim cl sorghyb rye, ryegrs rye 

Southeast Uplands hairy v, red cl, ryegrs, rye, wht cl, sorghyb, buckwheat, rye, 

berseem, sorghyb, cowpeas, rye, swt cl ryegrs, sub cl, sorghyb 

crim cl swt cl ryegrs rye 

Southeast Lowlands winter peas, ryegrs, wht cl, sorghyb, berseem, rye, rye, 

sub cl, hairy v, rye, cowpeas, swt cl wheat sorghyb 

berseem, sorghyb, rye, cowpeas 

crim cl sub cl sorghyb oats 

Great Lakes hairy v, red cl, ryegrs, rye, oats, sorghyb, berseem, rye, 

berseem, sorghyb, rye, swt cl ryegrs, rye, sorghyb 

crim cl swt cl ryegrs oats 

Midwest Corn Belt hairy v, red cl, rye, barley, wht cl, rye, sorghyb, rye, ryegrs, rye, 

berseem, sorghyb, ryegrs, swt cl wheat, sorghyb 

crim cl swt cl barley oats 

Northern Plains hairy v, swt cl, rye, barley, rye, sorghyb, medic, rye, rye, 

medics medic, swt cl barley swt cl barley sorghyb 

Southern Plains winter peas, rye, barley, rye, sorghyb, rye, rye, 

hairy v medic barley swt cl barley sorghyb 

Inland Northwest winter peas, medic, swt cl, rye, sorghyb, rye, wheat, rye, 

hairy v rye, barley barley swt cl barley sorghyb 

Northwest Maritime berseem, ryegrs, rye, wht cl, rye, sorghyb, ryegrs, rye 

sub cl, lana v, sorghyb, ryegrs, swt cl lana v, oats, 

crim cl lana v barley wht cl 

Coastal California berseem, ryegrs, rye, wht cl, sorghyb, rye, ryegrs, sorghyb, 

sub cl, sorghyb, cowpeas, swt cl berseem, crim cl, 

lana v, medic lana v rye, ryegrs wht cl rye 

Calif. Central Valley winter peas, medic, wht cl, sorghyb, ryegrs, sorghyb, 

lana v, sub cl, sub cl barley, rye, swt cl wht cl, rye, crim cl, 

medic ryegrs lana v rye 

Southwest medic, sub cl, barley, medic, 

sub cl medic, barley sorghyb barley 

1 ryegrs=annual ryegrass. sorghyb=sorghum-sudangrass hybrid. berseem=berseem clover. winter peas=Austrian winter pea. 

crim cl=crimson clover. hairy v=hairy vetch. red cl=red clover. sub cl=subterranean clover. swt cl=sweetclover. 

wht cl=white clover. lana vetch=LANA woollypod vetch. 

CHARTS 47

Chart 2 

PERFORMANCE AND ROLES 

Legume Total N Dry Matter N Soil Erosion Weed Good Quick 

Species N Source (lb./A) 1 (lb./A/yr.) Scavenger 2 Builder 3 Fighter 4 Fighter Grazing 5 Growth 

Annual ryegrass p. 55 2,000–9,000 

Barley p. 58 3,000–10,000 

N O N L E G U M E S 

Oats p. 62 2,000–10,000 

Rye p. 65 3,000–10,000 

Wheat p. 72 3,000–7,000 

Buckwheat p. 77 2,000–3,000 

Sorghum–sudan. p. 80 8,000–10,000 

Berseem clover p. 87 75–220 6,000–10,000 

Cowpeas p. 95 100–150 2,500–4,500 

Crimson clover p. 100 70–130 3,500–5,500 

Field peas p. 105 90–150 4,000–5,000 

L E G U M E S 

Hairy vetch p. 112 90–200 2,300–5,000 

Medics p. 119 50–120 1,500–4,000 

Red clover p. 127 70–150 2,000–5,000 

Subterranean clover p. 132 75–200 3,000–8,500 

Sweetclovers p. 139 90–170 3,000–5,000 

White clover p. 147 80–200 2,000–6,000 

Woollypod vetch p. 151 100–250 4,000–8,000 

1 Total N—Total N from all plant. 

2 N Scavenger—Ability to take up/store excess nitrogen. 

3 Soil Builder—Organic matter yield and 

soil structure improvement. 

4 Erosion Fighter—Soil-holding ability of roots and total plant. 

5 Good Grazing—Production, nutritional 

quality and palatability. 

=Poor; =Fair; =Good; =Very Good; =Excellent 


Chart 2 

PERFORMANCE AND ROLES continued 

Lasting 

Harvest Cash Crop 

Species Residue 1 Duration 2 Value 3 Interseed 4 Comments 

F* S* 


L E G U M E S 

Annual ryegrass 

Barley 

Oats 

Rye 

Wheat 

Buckwheat 

Sorghum–sudangrass 

Berseem clover 

Cowpeas 

Crimson clover 

Field peas 

Hairy vetch 

Medics 

Red clover 

Subterranean clover 

Sweetclovers 

White clover 

Woollypod vetch 

Heavy N and H20 user; cutting boosts 

dry matter significantly. 

Tolerates moderately alkaline conditions but 

does poorly in acid soil < pH 6.0. 

Prone to lodging in N-rich soil. 

Tolerates triazine herbicides. 

Heavy N and H20 user in spring. 

Summer smother crop; breaks down quickly. 

Mid-season cutting increases root penetration. 

Very flexible cover crop, green manure, forage. 

Season length, habit vary by cultivar. 

Established easily, grows quickly if planted early 

in fall; matures early in spring. 

Biomass breaks down quickly. 

Bi-culture with small grain expands seasonal 

adaptability. 

Use annual medics for interseeding. 

Excellent forage, easily established; widely adapted. 

Strong seedlings, quick to nodulate. 

Tall stalks, deep roots in second year. 

Persistent after first year. 

Reseeds poorly if mowed within 2 months of 

seeddrop; overgrazing can be toxic. 

1 Lasting Residue—Rates how long the killed residue remains on the surface. 

2 Duration—Length of vegetative stage. 

3 Harvest Value—Economic value as a forage (F) or as seed (S) or grain. 

4 Cash Crop Interseed—Rates how well the cover crop 

will perform with an appropriate companion crop. 


CHARTS 49

Chart 3A 

CULTURAL TRAITS 

heat 

drought 

shade 

flood 

low fert 

Hardy Tolerances Min. 

through pH Best Germin. 

Species Aliases Type 1 Zone 2 Habit 3 (Pref.) Established 4 Temp. 

Annual ryegrass p. 55 Italian ryegrass WA 6 U 6.0–7.0 Esp, LSu, 

EF, F 


Barley p. 58 WA 7 U 6.0–8.5 F,W, Sp 

Oats p. 62 spring oats CSA 8 U 4.5–6.5 LSu, ESP 

W in 8+ 

Rye p. 65 winter, cereal, CSA 3 U 5.0–7.0 LSu-F 34F 

or grain rye 

Wheat p. 72 WA 4 U 6.0–7.5 LSu, F 

Buckwheat p. 77 SA NFT U to 5.0–7.0 Sp to LSu 50F 

SU 

Sorghum–sudan. p. 80 Sudax SA NFT U 6.0–7.0 LSp, ES 65F 

Berseem clover p. 87 BIGBEE, SA,WA 7 U to 6.2–7.0 ESp, EF 42F 

multicut 

SU 

Cowpeas p. 95 crowder peas, SAL NFT SU/C 5.5–6.5 ESu 58F 

southern peas 

L E G U M E S 

Crimson clover p. 100 WA, SA 7 U/SU 5.5–7.0 LSu/ESu 

Field peas p. 105 winter peas, WA 7 C 6.0–7.0 F, ESp 41F 

black peas 

Hairy vetch p. 112 winter vetch WA/CSA 4 C 5.5–7.5 EF, ESp 60F 

Medics p. 119 SP/SA 4/ 7 P/Su 6.0–7.0 EF, ESp, ES 45F 

Red clover p. 127 SP, B 4 U 6.2–7.0 LSu; ESp 41F 

Subterranean cl. p. 132 subclover CSA 7 P/SP 5.5–7.0 LSu, EF 38F 

Sweetclovers p. 139 B/SA 4 U 6.5–7.5 Sp/S 42F 

White clover p. 147 white dutch LP/WA 4 P/SU 6.0–7.0 LW, E to 40F 

ladino 

LSp, EF 

Woollypod vetch p. 151 Lana CSA 7 SP, C 6.0–8.0 F 

1 B=Biennial; CSA=Cool season annual; LP=Long-lived perennial; SA=Summer annual; SP=Short-lived perennial;WA=Winter annual 

2 See USDA Hardiness Zone Map, inside front cover. NFT=Not frost tolerant. 

3 C=Climbing; U=Upright; P=Prostrate; SP=Semi-prostrate; 

SU=Semi-upright. 

4 E=Early; M=Mid; L=Late; F=Fall; Sp=Spring; Su=Summer;W=Winter 



Chart 3B 

PLANTING 

Cost Cost/A Inoc. 

Species Depth Seeding Rate ($/lb.) 1 (median) 2 Type Reseeds 3 

Drilled 

Broadcast 

lb./A bu/A lb./A bu/A oz./100 ft 2 drilled broadcast 

Annual ryegrass 0– 1 /2 5–10 .2–.4 15–30 .6–1.25 1 .50 3.75 11.25 R 


Barley 3 

/4–2 50–100 1–2 80–125 1.6–2.5 3-5 .05–.20 9.38 12.81 S 

Oats 1 

/2–2 80–110 2.5–3.5 110–140 3.5–4.5 4–6 .10–.20 14.25 18.75 R 

Rye 3 

/4–2 60–120 1-2 90–160 1.5–3.0 4–6 .05–.20 6.75 9.38 R 

Wheat 1 

/2–1 1 /2 60–120 1–2 60–150 1–2.5 3–6 .05–.25 13.50 15.75 S 

Buckwheat 1 

/2–1.5 48–70 1–1.4 60–96 1.2–1.5 3–4 .28–.70 29– 38– R 

Sorghum-sudangrass 1 

/2-1.5 35 1 40–50 1–1.25 2 .21–.66 15.05 19.35 S 

Berseem clover 1 

/4– 1 /2 8–12 15–20 2 1.50 15.00 27.00 crimson, N 

berseem 

Cowpeas 1–1 1 /2 30–90 70–120 5 .50 30 47.50 cowpeas, S 

lespedeza 

Crimson clover 1 

/4– 1 /2 15-20 22–30 2–3 1.50 26 39 crimson, R 

berseem 

L E G U M E S 

Field peas 1 1 /2–3 50–80 90–100 4 .25 16.25 26.25 pea, vetch S 

Hairy vetch 1 

/2-1 1 /2 15–20 25–40 2 1.25 22 41 pea, vetch S 

Medics 1 

/4– 1 /2 8–22 12–26 2/3 1.50 22.50 28.50 annual R 

medics 

Red clover 1 

/4– 1 /2 8–10 10–12 3 1.85 16.65 20.35 red cl, S 

wht cl 

Subterranean clover 1 

/4– 1 /2 10–20 20–30 3 2.50 37.50 62.50 clovers, R 

sub, rose 

Sweetclovers 1 

/4–1.0 6–10 10–20 1.5 .70 5.60 10.50 alfalfa, R 

swt cl 

White clover 1 

/4– 1 /2 3–9 5–14 1.5 3.10 18.60 29.50 red cl, R 

wht cl 

Woollypod vetch 1 

/2–1 10–30 30–60 2-3 1.05 21 47.25 pea, vetch R,S 

1 Per pound in 50-lb. bags as of summer/fall 1997; legumes especially subject to price changes due to supply variability.To locate places 

to buy seed, see Seed Suppliers (p. 166). 

2 Mid-point price at mid-point rate, seed cost only. 

3 R=Reliably; U=Usually; S=Sometimes; 

N=Never (reseeds). 

CHARTS 51

Chart 4A 

POTENTIAL ADVANTAGES 

Soil Impact Soil Ecology Other 

Frees Loosen choke attract bears short 

Species subsoiler P&K Topsoil nematodes disease allelopathic weeds beneficials traffic windows 

Annual ryegrass p. 55 

Barley p. 58 


Oats p. 62 

Rye p. 65 

Wheat p. 72 

Buckwheat p. 77 

Sorghum–sudangrass p. 80 

Berseem clover p. 87 

Cowpeas p. 95 

Crimson clover p. 100 

Field peas p. 105 

L E G U M E S 

Hairy vetch p. 112 

Medics p. 119 

Red clover p. 127 

Subterranean clover p. 132 

Sweetclovers p. 139 

White clover p. 147 

Woollypod vetch p. 151 



Chart 4B 

POTENTIAL DISADVANTAGES 

Species 

Annual ryegrass 

weed 

potential 

insects/ 

nematodes 

crop 

disease 

hinder 

crops 

Increase Pest Risks 

1 

Management Challenges 

establish 

till-kill 

mow-kill 

mature 

incorp. 

Comments Pro/Con 

If mowing, leave 3-4" to ensure 

regrowth. 


L E G U M E S 

Barley 

Oats 

Rye 

Wheat 

Buckwheat 

Sorghum–sudangrass 

Berseem clover 

Cowpeas 

Crimson clover 

Field peas 

Hairy vetch 

Medics 

Red clover 

Subterranean clover 

Sweetclovers 

White clover 

Woollypod vetch 

Can be harder than rye to incorporate 

when mature. 

Cleaned, bin-run seed will suffice. 

Can become a weed if tilled at 

wrong stage. 

Absorbs N and H20 heavily during 

stem growth, so kill before then. 

Buckwheat sets seed quickly. 

Mature, frost-killed plants become 

quite woody. 

Multiple cuttings 

needed to achieve maximum N. 

Some cultivars, nematode resistant. 

Good for underseeding, easy to 

kill by tillage or mowing. 

Susceptible to sclerotinia in East. 

Tolerates low fertility, wide pH range, 

cold or fluctuating winters. 

Perennials easily become weedy. 

Grows best where corn grows well. 

Cultivars vary greatly. 

Mature plants become woody. 

Can be invasive; survives tillage. 

Hard seed can be problematic; 

resident vegetation eventually displaces. 

1 Symbols, this page only: =Could be a major problem. =Could be a moderate problem. =Could be a minor problem. 

=Occasionally a minor problem. =Rarely a problem 

CHARTS 53

OVERVIEW OF NONLEGUME COVER CROPS 

Most of the commonly used nonlegume cover 

crops are grasses. These include: 

• Annual cereals (rye, wheat, barley, oats) 

• Annual or perennial forage grasses such as 

ryegrass 

• Warm-season grasses like sorghum-sudangrass 

Grass cover crops are most useful for: 

• Scavenging nutrients—especially N—left over 

from a previous crop 

• Reducing or preventing erosion 

• Producing large amounts of residue, and 

adding organic matter to the soil 

• Suppressing weeds 

Annual cereal grain crops have been used successfully 

in many different climates and cropping 

systems.Winter annuals usually are seeded in late 

summer or fall, establish and produce good root 

and topgrowth biomass before going dormant 

during the winter,then green up and produce significant 

biomass before maturing. Rye, wheat, and 

hardy triticale all follow this pattern, with some 

relatively small differences that will be addressed 

in the section for each cover crop. 

Perennial and warm-season forage grasses also 

can serve well as cover crops. Forage grasses, like 

sod crops, are excellent for nutrient scavenging, 

erosion control, biomass production and weed 

control. Perennials used as cover crops are usually 

grown for about one year. Summer-annual 

(warm-season) grasses may fill a niche for biomass 

production and weed or erosion control if the 

ground would otherwise be left fallow (between 

vegetable crops, for example). Buckwheat, while 

not a grass,is also a warm-season plant used in the 

same ways as summer-annual grasses. 

Grass cover crops are higher in carbon than 

legume cover crops.The high carbon content of 

grasses means that they will break down more 

slowly than legumes, resulting in longer-lasting 

residue. As grasses mature, the carbon-to-nitrogen 

ratio (C:N) increases. This has two tangible 

results: The higher carbon residue is harder for 

soil microbes to break down,so the process takes 

longer, and the nutrients contained in the cover 

crop residue usually are less available to the next 

crop. 

So although grass cover crops take up leftover N 

from the previous crop,as they mature the N is less 

likely to be released for use by a crop grown immediately 

after the grass cover crop. As an example of 

this, think of how long it takes for straw to decompose 

in the field.Over time,the residue does break 

down and nutrients are released. In general, this 

slower decomposition and the higher carbon content 

of grasses can lead to increased soil organic 

matter, compared to legumes. 

Grass cover crops can produce a lot of residue, 

which contributes to their ability to prevent erosion 

and suppress weeds while they are growing 

or when left on the soil surface as a mulch. 

Although grasses contain some nitrogen in 

their plant tissues, grass cover crops generally are 

not significant sources of N for your cropping system. 

They do, however, keep excess soil N from 

leaching, and prevent the loss of soil organic matter 

through erosion. 

Management of grasses in your cropping system 

may involve balancing the amount of residue 

produced with the possibility of tying up N for 

more than one season. Mixtures of grass and 

legume cover crops can alleviate the N-immobilization 

effect, can produce as much or more dry 

matter as a pure grass stand and may provide better 

erosion control due to the differences in 

growth habit.Suggestions for cover crop mixtures 

are found in the individual cover crop sections. 

In addition to grasses, another summer nonlegume 

is buckwheat, which is described in 

detail in its own section (p. 77). Buckwheat is 

usually classed as a non-grass coarse grain.While 

it is managed like a quick-growing grain, its has 

a succulent stem, large leaves and white 

blossoms. 


ANNUAL RYEGRASS 

Lolium multiflorum 

Also called: Italian ryegrass 

Type: cool season annual grass 

Roles: prevent erosion, improve 

soil structure and drainage, add 

organic matter, suppress weeds, 

scavenge nutrients 

Mix with: legumes, grasses 

See charts, pp. 47 to 53, for ranking 

and management summary. 

If you want mellower soil without investing 

much in a cover crop, consider annual ryegrass. 

A quick-growing, nonspreading bunch 

grass, annual ryegrass is a reliable, versatile performer 

almost anywhere, assuming adequate 

moisture and fertility. It does a fine job of holding 

soil,taking up excess N and outcompeting weeds. 

Ryegrass is an excellent choice for building soil 

structure in orchards, vineyards and other cropland 

to enhance water infiltration, water-holding 

capacity or irrigation efficiency. It can reduce soil 

splash on solanaceous crops and small fruit crops, 

decreasing disease and increasing crop quality. 

You also can overseed ryegrass readily into corn, 

soybeans and many high-value crops. 

BENEFITS 

Erosion fighter. Ryegrass has an extensive, 

soil-holding root system. The cover crop establishes 

quickly even in poor, rocky or wet soils and 

tolerates some flooding once established.It’s wellsuited 

for field strips, grass waterways or exposed 

areas. “An added bonus: It keeps you out of the 

mud at harvest,” says Pennsylvania grower Bob 

Hofstetter. 

Soil builder. Ryegrass’s dense yet shallow root 

system improves water infiltration and enhances 

soil tilth.Rapid aboveground growth helps supply 

organic matter. Expect about 4,000 to 6,000 lb. 

dry matter/A on average with a multicut regimen, 

climbing as high as 9,000 lb.DM/A over a full field 

season with high moisture and fertility. 

Weed suppressor. Mixed with legumes or 

grasses, annual ryegrass usually establishes first 

and improves early-season weed control. With 

adequate moisture, it serves well in Hardiness 

Zone 6 and warmer as a living mulch in highvalue 

systems where you can mow it regularly. It 

may winterkill elsewhere, especially without protective 

snow cover during prolonged cold snaps. 

Even so, its quick establishment in fall still would 

provide an excellent,winterkilled mulch for earlyspring 

weed suppression. 

Nutrient catch crop. A high N user, ryegrass can 

capture leftover N and reduce nitrate leaching over 

winter. Its extensive, fibrous root system can take 

up as much as 43 lb. N/A, a University of California 

study showed (367). It took up about 60 lb. N/A 

by mid-May following corn in a Maryland study. 

Cereal rye scavenged the same amount of N by 

mid-April on this silt loam soil (307). 

Nurse/companion crop. Ryegrass helps slowgrowing, 

fall-seeded legumes establish and over- 

ANNUAL RYEGRASS 55

however, especially with late-fall plantings. Drill 5 

to 10 lb./A, 1 /4 to 1 /2 inch deep. 

Noncertified seed will reduce seeding cost, 

although it can introduce weeds. Annual ryegrass 

also cross-pollinates with perennial ryegrass and 

other ryegrass species, so don’t expect a pure 

stand if seeding common annual ryegrass. 

Marianne Sarrantonio 

ANNUAL RYEGRASS (Lolium multiflorum) 

winter in the northern U.S., even if the ryegrass 

winterkills.It tends to outcompete legumes in the 

South. Ryegrass also is a very palatable forage.You 

can extend the grazing period in late fall and early 

spring by letting livestock graze cover crops of 

ryegrass or a ryegrass-based mix. 

MANAGEMENT 

Ryegrass prefers fertile, well-drained loam or sandy 

loam soils, but establishes well on many soil types, 

including poor or rocky soils. It tolerates clay or 

poorly-drained soils in a range of climates and will 

outperform small grains on wet soils (350). 

Annual ryegrass has a biennial tendency in cool 

regions. If it overwinters, it will regrow quickly 

and produce seed in late spring. Although few 

plants survive more than a year, this reseeding 

characteristic can create a serious weed problem 

in some areas, such as the mid-Atlantic (82). 

Establishment & Fieldwork 

Annual ryegrass germinates and establishes well 

even in cool soil (350). Broadcast seed at 15 to 30 

lb./A.You needn’t incorporate seed when broadcasting 

onto freshly cultivated soil—the first 

shower ensures seed coverage and good germination. 

Cultipacking can reduce soil heaving, 

Winter annual use. Seed in fall in Zone 6 or 

warmer. In Zone 5 and colder, seed from midsummer 

to early fall—but at least 40 days before 

your area’s first killing frost (150). 

If aerially seeding, increase rates at least 30 percent 

(12). You can overseed into corn at last 

cultivation or later (consider adding 5 to 10 

pounds of red or white clover with it) or plant 

right after corn silage harvest.Overseed at leaf-yellowing 

or later for dense-canopy crops such as 

soybeans (147, 150). When overseeding into 

solanaceous crops such as peppers, tomatoes and 

eggplant, wait until early to full bloom. 

Spring seeding. Sow ryegrass right after an 

early-spring vegetable crop, for a four- to eightweek 

summer period before a fall vegetable 

crop (302). 

Mixed seeding. Plant ryegrass at 8 to 15 lb./A 

with a legume or small grain, either in fall or early 

in spring. Ryegrass will dominate the mixture 

unless you plant at low rates or mow regularly. 

Seed the legume at about two-thirds its normal 

rate. Adequate P and K levels are important when 

growing annual ryegrass with a legume. 

In vineyards,a fall-seeded,50:50 mix of ryegrass 

and crimson clover works well, some California 

growers have found (167). 

Although not a frequent pairing, drilling ryegrass 

in early spring at 20 lb./A with an oats nurse 

crop or frost seeding 10 lb./A into overwintered 

small grains can provide some fine fall grazing. 

Frost seeding with red clover or other large-seeded, 

cool-season legumes also can work well. 

Maintenance. Avoid overgrazing or mowing ryegrass 

closer than 3 to 4 inches. A stand can persist 

many years in orchards,vineyards,and other areas 

if allowed to reseed naturally and not subject to 


prolonged heat, cold or drought.That’s rarely the 

case in Zone 5 and colder, however, where 

climate extremes take their toll.Perennial ryegrass 

may be a smarter choice if persistence is important. 

Otherwise, plan on incorporating the cover 

within a year of planting. Annual ryegrass is a 

relatively late maturing plant, so in vineyards 

it may use excessive water and N if left too 

long (168). 

Killing & Controlling 

You can kill annual ryegrass mechanically by disking 

or plowing, preferably during early bloom 

(usually in spring), before it sets seed (302, 351). 

Mowing may not kill ryegrass completely (77). 

You also can kill annual ryegrass readily with nonpersistent 

contact herbicides such as glyphosate 

or paraquat.When soil moisture conservation is a 

primary objective of the killed surface residue, 

paraquat would be better because it kills fast and 

conserves more moisture (82). 

To minimize N tie-up as the biomass decomposes, 

wait a few weeks after incorporation 

before you seed a subsequent crop. Growing ryegrass 

with a legume such as red clover would minimize 

the N concern. By letting the cover residue 

decompose a bit,you’ll also have a seedbed that is 

easier to manage. 

Pest Management 

Weed potential. Ryegrass can become a weed if 

allowed to set seed (302). It often volunteers in 

vineyards or orchards if there is high fertility and 

may require regular mowing to reduce competition 

with vines (351).A local weed management 

specialist may be able to recommend a herbicide 

that can reduce ryegrass germination if the cover 

is becoming a weed in perennial grass stands. 

Chlorsulfuron is sometimes used for this purpose 

in California (351). 

Insect and other pests. Ryegrass attracts few 

insect pests and generally can help reduce insect 

pest levels in legume stands and many vegetable 

crops, such as root crops and brassicas. Rodents 

are occasionally a problem when ryegrass is used 

as a living mulch. 

Rust occasionally can be a problem with annual 

ryegrasses, especially crown and brown rust. 

Look for resistant, regionally adapted varieties. 

Annual ryegrass also can host high densities of pin 

nematodes (Paratylenchus projectus) and 

bromegrass mosaic virus, which plant-parasitic 

nematodes (Xiphinema spp.) transmit (351). 

Other Options 

Ryegrass provides a good grazing option that can 

extend the grazing season for almost any kind of 

livestock. Although very small-seeded, ryegrass 

does not tiller heavily, so seed at high rates if you 

expect a ryegrass cover crop also to serve as a pasture. 

Some varieties tolerate heat fairly well and 

can persist for several years under sound grazing 

practices that allow the grass to reseed. 

As a hay option, annual ryegrass can provide 

2,000 to 6,000 pounds of dry forage per acre, 

depending on moisture and fertility levels (351). 

For highest quality hay, cut no later than the early 

bloom stage and consider growing it with a 

legume. 

When using ryegrass for grass waterways and 

conservation strips on highly erodible slopes, 

applying 3,000 to 4,000 pounds per acre of straw 

after seeding at medium to high rates can help 

keep soil and seed in place until the stand establishes 

(351). 

Management Cautions 

Ryegrass is a heavy user of moisture and N. It 

performs poorly during drought or long periods 

of high or low temperature, and in low-fertility 

soils. It can compete heavily for soil moisture 

when used as living mulch. It also can become a 

weed problem (302). 

COMPARATIVE NOTES 

• Establishes faster than perennial ryegrass but 

is less cold-hardy 

• Less persistent but easier to incorporate than 

perennial ryegrass 

• About half as expensive as perennial ryegrass 

Seed sources. Widely available. 

ANNUAL RYEGRASS 57

BARLEY 

Hordeum vulgare 

Type: cool season annual cereal 

grain 

Roles: prevent erosion, suppress 

weeds, scavenge excess nutrients, 

add organic matter 

Mix with: annual legumes or 

grasses, perennial ryegrass 



Inexpensive and easy to grow, barley provides 

exceptional erosion control and weed suppression 

in semi-arid regions and in light soils. 

It also can fill short rotation niches or serve as a 

topsoil-protecting crop during droughty conditions 

in any region. 

It’s a fine choice for reclaiming overworked, 

weedy or eroded fields, or as part of a cover crop 

mix for improving soil tilth and nutrient cycling in 

perennial cropping systems in Hardiness Zone 8 

or warmer. 

Barley prefers cool,dry growing areas. A spring 

cover crop,it can be grown farther north than any 

other cereal grain, largely because of its short 

growing period.It also can produce more biomass 

in a shorter time than any other cereal crop (219). 

BENEFITS 

Erosion control. Use barley as an overwintering 

cover crop for erosion control in Zone 8 and 

warmer, including much of California, western 

Oregon and western Washington. It’s well-suited 

for vineyards and orchards, or as part of a mixed 

seeding. 

As a winter annual, barley develops a deep, 

fibrous root system. The roots can reach as deep 

as 6.5 feet. As a spring crop, barley has a comparatively 

shallow root system but holds soil strongly to 

minimize erosion during droughty conditions (51). 

Nutrient recycler. Considered a light N feeder, 

barley captured 32 lb. N/A as a winter cover crop 

following a stand of fava beans (Vicia faba) in a 

California study,compared with 20 lb./A for annual 

ryegrass. A barley cover crop reduced soil N 

an average of 64 percent at eight sites throughout 

North America that had received an average of 

107 lb. N/A (213). Intercropping barley with field 

peas (Pisum sativum) can increase the amount 

of N absorbed by barley and returned to the soil 

in barley residue, other studies show (172, 175). 

Barley improves P and K cycling if the residue 

isn’t removed. 

Weed suppressor. Quick to establish,barley outcompetes 

weeds largely by absorbing soil moisture 

during its early growing stages. It also shades 

out weeds and releases allelopathic chemicals 

that help suppress them. 

Tilth-improving organic matter. Barley is a 

quick source of abundant biomass that, along 

with its thick root system, can improve soil 

structure and water infiltration (219, 367). In 

California cropping systems, cultivars such as 

UC476 or COSINA can produce as much as 12,900 

lb. biomass/A. 

Nurse crop. Barley has an upright posture and 

relatively open canopy that makes it a fine nurse 


crop for establishing a forage or legume stand. 

Less competitive than winter grains, barley also 

uses less water than other covers.In weedy fields, 

wait to broadcast the forage or legume until after 

you’ve mechanically weeded barley at the four- or 

five-leaf stage to reduce weed competition. 

As an inexpensive,easy-to-kill companion crop, 

barley can protect sugarbeet seedlings during 

their first two months while also serving as a soil 

protectant during droughty periods (details 

below). 

Pest suppression. Barley 

can reduce incidence of 

leafhoppers, aphids, armyworms, 

root-knot nematodes 

and other pests, a number of 

studies suggest. 

MANAGEMENT 


Barley establishes readily in prepared seedbeds. It 

prefers adequate but not excessive moisture and 

does poorly in waterlogged soils. It grows best in 

well-drained, fertile loams or light, clay soils in 

areas having cool, dry, mild winters. It also does 

well on light, droughty soils and tolerates somewhat 

alkaline soils better than other cereal crops. 

With many varieties of barley to choose from, 

be sure to select a regionally adapted one. Many 

are well-adapted to high altitudes and cold, short 

growing seasons. 

Spring annual use. Drill at 50 to 100 lb./A (1 to 

2 bushels) from 3 /4 to 2 inches deep into a prepared 

seedbed. Hoe or furrow-type drills with 

disk- or double-disk openers work well in arid 

regions without irrigation. 

If broadcasting, prepare the seedbed with at 

least a light field cultivation. Sow 80 to 125 lb./A 

(1.5 to 2.5 bushels) and harrow, cultipack or disk 

lightly to cover. Use a lower rate (25 to 50 

pounds) if overseeding as a companion crop or a 

higher rate (140 pounds) for very weedy fields. 

When broadcasting, consider seeding half in one 

direction, then the rest in a perpendicular direction 

for better coverage (51). 

A fast-growing barley can 

be grown farther north and 

produce more biomass in a 

shorter time than any other 

cereal grain. 

Winter annual use. For an overwintering cover 

crop in Zone 8 or warmer, plant barley from 

September through February. Plantings before 

November 1 generally fare best, largely due to 

warmer soil conditions. Elsewhere, winter varieties 

might overwinter only in mild areas with 

adequate snow cover. 

Expect mixed results if trying to use barley as a 

self-reseeding cover crop.Weather variations,mowing 

regimes and the return of native or resident 

vegetation tend to reduce 

barley’s reseeding capability. 

Expect to resow periodically, 

perhaps annually. 

Mixed seedings. Barley 

works well in mixtures with 

other grasses or legumes. In 

low-fertility soils or where 

you’re trying to minimize 

tie-up of soil nitrogen, growing barley with one or 

more legumes can be helpful. Your seeding cost 

per pound will increase, but the reduced seeding 

rate can offset some of this. A short-season 

Canadian field pea such as TRAPPER would be a 

good companion, or try an oat/barley/pea mix, 

suggests organic farmer Jack Lazor,Westfield,Vt. 

In northern California, Phil LaRocca (LaRocca 

Vineyards, Forest Ranch, Calif.) lightly disks his 

upper vineyard’s soil before broadcasting a mix 

of barley, fescue, brome, LANA vetch, and crimson, 

red and subterranean clovers, usually during 

October. He seeds at 30 to 35 lb./A, with 10 to 

20 percent being barley. “I’ve always added 

more barley to the seeding rate than recommended. 

More is better, especially with barley, 

if you want biomass and weed suppression,” 

he says. 

After broadcasting, LaRocca covers erosionprone 

areas with 2 tons of rice straw per acre, 

which is “$1 cheaper per bale than oat straw here 

and has fewer weed seeds,” he notes.“The straw 

decomposes quickly and holds seed and soil 

well.” Besides contributing to soil humus (as the 

cover crop also does), the straw helps keep the 

seedbed warm and moist. That can be very 

helpful in LaRocca’s upper vineyard, where it 

sometimes snows in winter. 

BARLEY 59

Elayne Sears 

BARLEY (Hordeum vulgare) 

In his other, less-erodible vineyard, LaRocca 

disks up the cover vegetation, then runs a harrow 

quickly on top of the disked alleyways to set a 

seedbed before broadcasting and cultipacking a 

similar mix of cover crops. 

Field Management 

Although barley absorbs a lot of water in its early 

stages,it uses moisture more efficiently than other 

cereals and can be grown without irrigation. 

About half the commercial barley acreage in dryland 

areas is irrigated, however. California cropping 

systems that include barley tend to be 

irrigated as well. Low seeding rates won’t necessarily 

conserve moisture, as vegetative growth 

often increases. 

LaRocca hasn’t had any moisture problems or 

grape-yield concerns from growing barley or 

other cover crops, even in the 40 percent of his 

upper vineyard that isn’t furrow-irrigated.“Once 

your vines are established, their root system is 

deeper and much more competitive than a typical 

cover crop’s root system,” he observes. 

Mowing can postpone and prolong barley 

flowering, as with other cereal grains. As a 

spring cover, barley puts on biomass quickly, so 

you can kill it in plenty of time for seeding a 

following crop.If you want barley to reseed,don’t 

mow until most of the stand has headed and seed 

is about to fall off. 

To encourage reseeding of his cover mix, Phil 

LaRocca allows every other row in his upper vineyard 

to go to seed, then disks it down. That lets 

him skip reseeding some blocks. 

If you’re concerned about barley reseeding or 

crop competition when intercropped, however, 

plant a lighter stand, suggests Alan Brutlag, 

Wendell, Minn. During droughty conditions, he 

broadcasts 25 to 30 pounds of barley per acre as 

a soil-protective companion crop for sugarbeet 

seedlings. The low-density stand is easy to stunt 

or kill a month later with the combination of 

herbicides and crop oil that he uses for weed 

control in his sugarbeets.Another control option 

is a single application of a herbicide labeled for 

grass control (37). 

Killing 

Kill barley with a grass herbicide in late spring, or 

by disking or mowing at the mid- to late-bloom 

stage but before it starts setting seed. 

If plant-parasitic nematodes have been a problem, 

incorporate overwintered barley early in 

spring, before warm temperatures encourage 

nematode populations. 


Annual weeds and lodging can occur when growing 

barley in high-fertility soils, although these 

wouldn’t pose problems in a barley cover crop. 

Despite their less dense canopy, six-rowed varieties 

tend to be taller and more competitive 

against weeds than two-rowed varieties. If you’re 

considering a grain option, harrowing or hoeing 

just before barley emergence could reduce weeds 

that already have sprouted. 

Barley produces alkaloids that have been 

shown to inhibit germination and growth of 

white mustard (196).These exudates also protect 


arley plants from fungus, armyworm larvae, 

bacteria and aphids (197, 374). 

Barley seems to reduce the incidence of grape 

leafhoppers in vineyards and increase levels 

of beneficial spiders, one California grower 

observed (167). Growing high-biomass cover 

crops such as barley or rye increased populations 

of centipedes,predator mites and other important 

predators, independent of tillage system used, a 

study in the Pacific Northwest found (366). 

Cutworms and other small grain pests can be 

occasional problems. Some perennial crop growers 

in California report increased incidence of 

gophers when growing cover crop mixes and try 

to minimize this by encouraging owl populations. 

Avoid seeding in cold, damp soils, which makes 

barley more prone to fungus and disease. Assuming 

adequate soil moisture, shallow seeding can 

hasten emergence and lessen incidence of root rot 

disease, if this has been a problem in your area 

(325). Varieties resistant to leaf diseases are available. 

Two-rowed varieties are more resistant to 

leaf rust and mildew. Also avoid planting barley 

after wheat. 

If nematodes are likely to be a problem, plant 

late in fall or during winter to avoid warm-season 

growth and incorporate early in spring in Zone 8 

and warmer. Barley can be a host for a nematode 

species (Meloidogyne javanica) that adversely 

affects Thompson seedless grapes. 

Barley drastically reduced root-knot nematode 

(Meloidogyne hapla M. Chitwood) populations 

and increased marketable carrot yields by at least 

seventeen-fold in a Quebec study comparing 

three-year rotations (191.1). 

Other Options 

Barley can be grazed lightly in winter or spring or 

cut for hay/haylage (147). It has greater forage 

nutritive value than oats, wheat or triticale. It also 

can be grown as a specialty grain for malting, 

soups, bread and other uses. As a feed grain (in a 

hog ration, for example), it can replace some 

costlier corn. 


• Barley tillers more than oats and also is more 

drought-tolerant, but oats generally perform 

better as a companion crop or winterkilled 

nurse crop because they are less competitive 

than barley (325). 

• Barley tolerates alkaline soils better than any 

other cereal. 

• Winter cultivars are less winterhardy than winter 

wheat, triticale or cereal rye. 

SEED 

Cultivars. Many commercial varieties are available. 

Look for low-cost, regionally adapted cultivars 

with at least 95-percent germination. 

Six-rowed cultivars are better for overseeding, 

and are more heat- and drought-tolerant. Tworowed 

types have more symmetrical kernels and 

are more disease-resistant (e.g. leaf rust and 

mildew) than six-rowed types, in which twothirds 

of the lateral rows of the spike are smaller 

and twisted. 


BARLEY 61

OATS 

Avena sativa 

Also called: spring oats 


Roles: suppress weeds, prevent 

erosion, scavenge excess nutrients, 

add biomass, nurse crop 

Mix with: clover, pea, vetch or 

other legumes 



nonsummer use 

CSA 

If you need a low-cost, reliable fall cover that 

winterkills in Hardiness Zone 6 and colder and 

much of Zone 7, look no further. Oats provide 

quick, weed-suppressing biomass, take up excess 

soil nutrients and can improve the productivity of 

legumes when planted in mixtures. The cover’s 

fibrous root system also holds soil during coolweather 

gaps in rotations,and the ground cover provides 

a mellow mulch before low-till or no-till crops. 

An upright,annual grass,oats thrive under cool, 

moist conditions on well-drained soil. Plants can 

reach heights in excess of 4 feet. Stands generally 

fare poorly in hot, dry weather. 

BENEFITS 

You can depend on oats as a versatile,quick-growing 

cover for many benefits: 

Affordable biomass. With good growing conditions 

and sound management (including timely 

planting), expect 2,000 to 4,000 pounds of dry 

matter per acre from late-summer/early fall-seeded 

oats and up to 8,000 pounds per acre from 

spring stands. Seeding (whether broadcasting or 

drilling), labor, equipment and management costs 

for a fall oat stand averaged less than $40/A for a 

group of northwestern Washington growers in a 

recent study. Budgets for seeding cereal cover 

crops look even better in the southeastern U.S., 

generally about $25 per acre (287). 

Nutrient catch crop. Oats take up excess N and 

small amounts of P and K when planted early 

enough. Late-summer plantings can absorb as 

much as 77 lb. N/A in an eight- to ten-week period, 

studies in the Northeast and Midwest have 

shown (252, 268). 

Where the plant winterkills, some farmers use 

oats as a nitrogen catch crop after summer 

legume plowdowns, to hold some legume N over 

winter without needing to kill the cover in spring. 

Some of that N disappears by spring, either 

through denitrification into the atmosphere or by 

leaching from the soil profile. Consider mixing 

oats with an overwintering legume if spring nitrogen 

is your main concern. 

Smother crop. Quick to germinate, oats are a 

great smother crop that outcompetes weeds and 

also provides allelopathic residue that can hinder 

germination of many weeds—and some crops 

(see below)—for a few weeks. Reduce crop suppression 

concerns by waiting three weeks after 

killing oats before planting a subsequent crop. 

Fall legume nurse crop. Oats have few equals 

as a legume nurse crop or companion crop.They 


can increase the fertilizer replacement value of 

legumes, studies have shown. Adding about 35 

to 75 lb. oats/A to the seeding mix helps slowestablishing 

legumes such as hairy vetch, clovers 

or winter peas, while increasing biomass. It also 

helps reduce fall weeds. The oats will winterkill 

in many areas while improving the legume’s 

winter survival. 

Spring green manure or companion crop. 

Spring-seeded with a legume, oats can provide 

hay or grain and excellent straw in the Northern 

U.S., while the legume remains as a summer—or 

even later—cover. There’s also a haylage option 

with a fast-growing legume if you harvest when 

oats are in the dough stage. The oats will increase 

the dry matter yield and boost the total protein, 

but could pose a nitrate-poisoning 

threat, especially if you delay 

harvesting until oats are nearing 

the flowering stage. 

The climbing growth habit of 

some viny legumes such as vetch 

can contribute to lodging and 

make oat grain harvest difficult. 

If you’re growing the legume for seed, the oats 

can serve as a natural trellis that eases combining. 

MANAGEMENT 


Time seeding to allow at least six to 10 weeks of 

cool-season growth. Moderately fertile soil gives 

the best stands. 

Late-summer/early-fall planting. For a winterkilled 

cover, spring oats usually are seeded in 

late summer or early fall in Zone 7 or colder. 

Broadcasting or overseeding will give the best 

results for the least cost, unless planting into 

heavy residue. Cleaned, bin-run seed will suffice. 

If broadcasting and you want a thick winterkilled 

mulch, seed at the highest locally recommended 

rate (probably 3 to 4 bushels per acre) 

at least 40 to 60 days before your area’s first 

killing frost. Assuming adequate moisture for 

quick germination,the stand should provide some 

soil-protecting, weed-suppressing mulch. 

Oats are a reliable, 

low-cost cover that 

winterkill in Zone 6 

and much of Zone 7. 

One low-cost seeding method is to set the combine 

so it blows the lightweight oats out the back 

at about 2 to 4 bushels per acre. Disk lightly to 

incorporate. In many regions, you’ll have the 

option of letting it winterkill or sending in cattle 

for some fall grazing. 

If seeding oats as a fall nurse crop for a legume, 

a low rate (1 to 2 bushels per acre) works well. 

If drilling oats, seed at 2 to 3 bushels per acre 

1 

/2 to 1 inch deep, or 2 inches when growing 

grain you plan to harrow for weed control.When 

seeding into residue, a good no-till drill can save 

time and also provide a firm seedbed that 

legumes like (102). 

Shallow seeding in moist soil provides rapid 

emergence and reduces incidence of root rot disease. 

Drilling spring oats in fall can provide 

seedlings with slightly more frost 

resistance than broadcasting and 

could extend the growing season 

a bit if you can’t fit in a latesummer 

seeding. 

Timing is critical when you 

want plenty of biomass or a 

thick ground cover. Overseeding 

the large-seeded oats into a standing crop or 

heavy residue could be difficult. As a winter 

cover following soybeans in the Northeast or 

Midwest, however, overseeding spring oats at 

the leaf-yellowing or early leaf-drop stage (and 

with little residue present) can give a combined 

ground cover as high as 80 percent through 

early winter (156). If you wait until closer to or 

after soybean harvest, however, you’ll obtain 

much less oat biomass to help retain bean 

residue, Iowa and Pennsylvania studies have 

shown. 

Delaying planting by as little as two weeks 

in late summer also can reduce the cover’s 

effectiveness as a spring weed fighter, a study in 

upstate New York showed. By spring, oat plots 

that had been planted on August 25 had 39 

percent fewer weed plants and one-seventh 

the weed biomass of control plots with no 

oat cover, while oats planted two weeks later 

had just 10 percent fewer weed plants in spring 

and 81 percent of the weed biomass of control 

plots (268, 269). 

OATS 63


OATS (Avena sativa) 

No-hassle fieldwork. As a winterkilled cover, 

just light disking in spring will break up the brittle 

oat residue. That exposes enough soil for 

warming and timely planting. Or, no-till directly 

into the mulch, as the residue will decompose 

readily early in the season. 

Winter planting. As a fall or winter cover crop 

in Zone 8 or warmer, seed oats at low to medium 

rates.You can kill winter-planted oats with spring 

plowing, or with herbicides in reduced-tillage 

systems. 

Spring planting. Seeding rate depends on your 

intended use: medium to high rates for a spring 

green manure and weed suppressor, low rates for 

mixtures or as a legume companion crop. Higher 

rates may be needed for wet soils or thicker 

ground cover. Excessive fertility can encourage 

lodging, but if you’re growing oats just for its 

cover value,that can be an added benefit for weed 

suppression and moisture conservation. 

Easy to kill. When oats are grown as a green 

manure and weed suppressor before an annual 

cash crop, kill the oat stand by mowing or spraying 

soon after the vegetative stage, such as the 

milk or soft dough stage. Killing too early reduces 

the biomass potential and you could see some 

regrowth. But waiting too long could make tillage 

of the heavier growth more difficult in a conventional 

tillage system and could deplete soil moisture 

needed for the next crop.Timely killing also 

is important because well-established or mature 

oat stands can tie up nitrogen. 

If you want to incorporate the stand, allow at 

least two to three weeks before planting the next 

crop. You can mow the oats for mulch if you’re 

not concerned that it might slow soil warming. 


Allelopathic (naturally occurring herbicidal) 

compounds in oat roots and residue can hinder 

weed growth for a few weeks.These compounds 

also can slow germination or root growth of some 

subsequent crops, such as lettuce, cress, timothy, 

rice, wheat and peas. Minimize this effect by waiting 

three weeks after oat incorporation before 

seeding a susceptible crop, or by following with 

an alternate crop. Rotary hoeing or other preemerge 

mechanical weeding of solo-seeded oats 

can improve annual broadleaf control. 

Oats are less prone to insect problems 

than wheat or barley. If you’re growing oats for 

grain or forage, armyworms, various grain aphids 

and mites, wireworms, cutworms, thrips, leafhoppers, 

grubs and billbugs could present 

occasional problems. 

Resistant oat varieties can minimize rusts, 

smuts and blights if they are a concern in your area 

or for your cropping system. Cover crops such as 

oats help reduce root-knot nematodes and 

vegetable crop diseases caused by Rhizoctonia, 

preliminary results of a producer study in South 

Carolina show (369). To reduce harmful nematodes 

that oats could encourage, avoid planting 

oats two years in a row or after nematodesusceptible 

small grains such as wheat, rye or 

triticale (51). 

Other Options 

There are many low-cost, regionally adapted and 

widely available oat varieties, so you have hay, 

straw, forage or grain options. Select for 


cultural and local considerations that best fit your 

intended uses. Day-length, stalk height, resistance 

to disease, dry matter yield, grain test weight and 

other traits may be important considerations. In 

the Deep South, fast-growing black oats (Avena 

strigosa) look promising as a weed-suppressive 

cover for soybeans (287). See Up-and-Coming 

Cover Crops (p. 158). 

Aside from their value as a cover crop, oats are 

a great feed supplement, says grain and hog 

farmer Carmen Fernholz, Madison, Minn. A niche 

market for organic oats also could exist in your 

area, he observes. 

Oats are more palatable than rye and easily 

overgrazed. If using controlled grazing in oat 

stands, watch for high protein levels, which can 

vary from 12 to 25 percent (356).The potassium 

level of oat hay also is sometimes very high and 

could cause metabolic problems in milking cows 

if it’s the primary forage (176). Underseeding a 

legume enhances the forage option for oats by 

increasing the biomass (compared with solocropped 

oats) and providing nitrogen for a subsequent 

crop. 


• Fall brassicas grow faster, accumulate more N 

and may suppress weeds better than oats. 

• Rye grows more in fall and early spring, 

absorbs more N and matures faster, but is 

harder to establish, to kill and to till than oats. 

• As a legume companion/nurse crop, oats outperform 

most varieties of other cereal grains. 

• Oats are more tolerant of wet soil than is 

barley, but require more moisture. 


RYE 

Secale cereale 

Also called: cereal rye, winter rye, 

grain rye 


grain 

Roles: take up excess N, prevent 

erosion, add organic matter, 

suppress weeds, companion crop 

Mix with: legumes, grasses or other 

cereal grains 



The hardiest of cereals, rye can be seeded 

later in fall than other cover crops and still 

provide considerable dry matter, an extensive 

soil-holding root system,significant reduction 

of nitrate leaching and exceptional weed sup- 

pression. Inexpensive and easy to establish, rye 

outperforms all other cover crops on infertile, 

sandy or acidic soil or on poorly prepared land. It 

is widely adapted, but grows best in cool, temperate 

zones or high altitudes. 

RYE 65

Taller and quicker-growing than wheat, rye can 

serve as a windbreak and trap snow or hold rainfall 

over winter. It overseeds readily into many 

high-value and agronomic crops and resumes 

growth quickly in spring, allowing timely killing 

by mowing or herbicides. Pair rye with a winter 

annual legume such as hairy vetch to offset rye’s 

tendency to tie up soil nitrogen in spring. 

BENEFITS 

Nutrient catch crop. Rye is the best cool-season 

cereal cover for absorbing unused soil N.It has no 

taproot, but rye’s quick-growing, fibrous root system 

can take up and hold as much as 100 lb. N/A 

until spring, with 25 to 50 lb. N/A more typical 

(351). Early seeding is better than late seeding for 

scavenging N (30). 

• A Maryland study credited rye with holding 

60 percent of the residual N that could have 

leached from a silt loam soil following 

intentionally over-fertilized 

corn (307). 

• A Georgia study estimated rye 

captured from 69 to 100 percent 

of the residual N after a 

corn crop (177). 

• In an Iowa study, overseeding 

rye or a rye/oats mix into soybeans in August 

limited leaching loss from September to May 

to less than 5 lb. N/A (252). 

Rye increases the concentration of exchangeable 

potassium (K) near the soil surface, by bringing 

it up from lower in the soil profile (94). 

Rye’s rapid growth (even in cool fall weather) 

helps trap snow in winter, further boosting winterhardiness. 

The root system promotes better 

drainage, while rye’s quick maturity in spring— 

compared with other cover crops—can help conserve 

late-spring soil moisture. 

Reduces erosion. Along with conservation tillage 

practices, rye provides soil protection on sloping 

fields and holds soil loss to a tolerable level (95). 

Fits many rotations. In most regions, rye can 

serve as an overwintering cover crop after corn 

Rye can be planted 

later in fall than 

other cover crops. 

or before or after soybeans, fruits or vegetables. 

It’s not the best choice before a small grain crop 

such as wheat or barley unless you can kill rye 

reliably and completely, as volunteer rye seed 

would lower the value of other grains. 

Rye also works well as a strip cover crop and 

windbreak within vegetables or fruit crops and 

as a quick cover for rotation gaps or if another 

crop fails. 

You can overseed rye into tasseling or silking 

corn with consistently good results.You also can 

overseed rye into brassicas (304, 351), into soybeans 

just before leaf drop or between pecan tree 

rows (43). 

Plentiful organic matter. An excellent source 

of residue in no-till and minimum-tillage systems 

and as a straw source, rye provides up to 10,000 

pounds of dry matter per acre, with 3,000 to 

4,000 pounds typical in the Northeast (302). A 

rye cover crop might yield too much residue, 

depending on your tillage system, 

so be sure your planting regime for 

subsequent crops can handle this. 

Rye overseeded into cabbage 

August 26 covered nearly 80 percent 

of the between-row plots by 

mid-October and, despite some 

summer heat,already had accumulated nearly half 

a ton of biomass per acre in a New York study. By 

the May 19 plowdown, rye provided 2.5 tons of 

dry matter per acre and had accumulated 80 lb. 

N/A. Cabbage yields weren’t affected, so competition 

wasn’t a problem (268). 

Weed suppressor. Rye is one of the best cool 

season cover crops for outcompeting weeds, 

especially small-seeded, light-sensitive annuals 

such as lambsquarters, redroot pigweed, velvetleaf, 

chickweed and foxtail. Rye also suppresses 

many weeds allelopathically (as a natural 

herbicide), including dandelions and Canada thistle 

(300) and has been shown to inhibit germination 

of some triazine-resistant weeds (275). 

Rye reduced total weed density an average of 

78 percent when rye residue covered more than 

90 percent of soil in a Maryland no-till study 


(339), and by 99 percent in a California study 

(351). You can increase rye’s weed-suppressing 

effect before no-till corn by planting rye with 

an annual legume such as hairy vetch (82). 

Pest suppressor. While rye is susceptible to the 

same insects that attack other cereals, serious 

infestations are rare.Rye reduces insect pest problems 

in rotations (369) and attracts significant 

numbers of beneficials such as lady beetles (38). 

Fewer diseases affect rye than other cereals. 

Rye can help reduce root-knot nematodes and 

other harmful nematodes, research in the South 

suggests (14, 369). 

Companion crop/legume mixtures. Sow 

rye with legumes or other grasses in fall or 

overseed a legume in spring. A legume helps offset 

rye’s tendency to tie up N. A legume/rye mixture 

adjusts to residual soil N levels. If there’s 

plenty of N, rye tends to do better; if there is 

insufficient N, the legume component grows 

better, Maryland research shows (59). Hairy 

vetch and rye are a popular mix, allowing an 

N credit before corn of 50 to 100 lb. N/A. 

Rye also helps protect the less hardy vetch 

seedlings through winter. 

Rye Smothers Weeds Before Soybeans 

An easy-to-establish rye cover crop helps 

Napoleon, Ohio, farmer Rich Bennett enrich 

his sandy soil while trimming input costs in 

no-till soybeans. Bennett broadcasts rye at 2 

bushels per acre on corn stubble in late 

October. He chops the cornstalks after rye 

seeding to ensure easy bean planting and 

cultivation in spring. 

Bennett doesn’t incorporate rye seed, 

having found that it germinates well on the 

soil surface under the chopped cornstalks. It 

usually breaks through the ground but shows 

little growth before winter dormancy. Seeded 

earlier in fall, rye would provide more residue 

than Bennett prefers by bean planting—and 

more effort to kill the cover. “Even if I don’t 

see any rye in fall, I know it’ll be there in 

spring, even if it’s a cold or wet one,” he says. 

By mid-May, the rye is usually at least 2.5 

feet tall and hasn’t started heading.“If it’s 

shorter than 15 to 18 inches, rye won’t do 

a good enough job of shading out broadleaf 

weeds,” notes Bennett, who likes how rye 

suppresses foxtail, pigweed and lambsquarters. 

He sprays the rye with herbicide and no-tills 

beans at 70 pounds per acre on 30-inch rows 

in a single pass to minimize rye knockdown 

from field equipment.“I kill the rye with 1.5 

pints of Roundup per acre—about half the 

recommended rate—and sometimes add 

1 quart of Lasso to control nightshade. Adding 

1.7 pounds of ammonium sulfate and 13 

ounces of surfactant per acre makes it easier 

for Roundup to penetrate rye leaves,” he 

explains. 

The cover dies in about two weeks.The 

slow kill helps rye suppress weeds while 

soybeans establish. In this system, Bennett 

doesn’t have to worry about rye regrowing. 

He usually cultivates beans twice, using 

a Buffalo no-till cultivator that handles rye 

residue easily. Bennett figures the rye saves 

him $15 to $30 per acre in material costs 

and fieldwork, compared with conventional 

no-till systems for soybeans. 

Rye doesn’t hurt his bean yields, either. 

Usually at or above county average, his yields 

range from 45 to 63 bushels per acre, 

depending on rainfall, says Bennett. 

“I really like rye’s soil-saving benefits,” he 

says.“Rye reduces our winter wind erosion, 

improves soil structure, conserves soil 

moisture and reduces runoff.”Although he 

figures the rye’s restrained growth (from 

the late fall seeding) provides only limited 

scavenging of leftover N, any that it does 

absorb and hold overwinter is a bonus. 

RYE 67


CEREAL RYE (Secale cereale) 

MANAGEMENT 


Rye prefers light loams or sandy soils and will germinate 

even in fairly dry soil. It also will grow in 

heavy clays and poorly drained soils, and many 

cultivars tolerate waterlogging. (44.1) 

Rye can establish in very cool weather. It will 

germinate at temperatures as low as 34 F. 

Vegetative growth requires 38 F or higher (302). 

Winter annual use. Seed from late summer to 

midfall in Hardiness Zones 3 to 7 and from fall to 

midwinter in Zones 8 and warmer. In the Upper 

Midwest and cool New England states, seed two 

to eight weeks earlier than a wheat or rye grain 

crop to ensure maximum fall, winter and spring 

growth. Elsewhere, your tillage system and the 

amount of fall growth you prefer will help determine 

planting date. Early planting increases the 

amount of N taken up before winter, but can 

make field management (especially killing the 

cover crop and tillage) more difficult in spring. 

See Rye Smothers Weeds Before Soybeans (p. 67). 

Rye is more sensitive to seeding depth than 

other cereals, so plant no deeper than 2 inches 

(51). Drill 60 to 120 lb./A (1 to 2 bushels) into a 

prepared seedbed or broadcast 90 to 160 lb./A 

(1.5 to 3 bushels) and disk lightly or cultipack 

(302, 351). If broadcasting late in fall and your 

scale and budget allow,you can increase the seeding 

rate to as high as 300 or 350 lb./A (about 6 

bushels) to ensure an adequate stand. 

“Rye is the only cover crop I’ve found that you 

can successfully overseed by air, year in and year 

out,”observes Mark Davis, an ag business management 

Extension specialist in Dover, Del.“Rye will 

germinate and grow on concrete,” he jokes. 

“I use a Buffalo Rolling Stalk Chopper to help 

shake rye seeds down to the soil surface,” says 

Steve Groff, a Holtwood, Pa., vegetable grower. 

“It’s a very consistent, fast and economical way to 

establish rye in fall.” (Groff’s farming system is 

described in detail on the World Wide Web at 

http://www2.epix.net/~cmfarm). 

Mixed seeding. Plant rye at the lowest locally 

recommended rate when seeding with a legume 

(302), and at low to medium rates with other 

grasses.In a Maryland study,a mix of 42 pounds of 

rye and 19 pounds of hairy vetch per acre was the 

optimum fall seeding rate before no-till corn on a 

silt loam soil (61). If planting with clovers, seed 

rye at a slightly higher rate, about 56 lb. per acre. 

For transplanting tomatoes into hilly, erosionprone 

soil, Steve Groff fall-seeds a per-acre mix of 

30 pounds rye, 25 pounds hairy vetch and 10 

pounds crimson clover. He likes how the threeway 

mix guarantees biomass, builds soil and provides 

N. 

Spring seeding. Although it’s not a common 

practice, you can spring seed cereals such as rye 

as a weed-suppressing companion, relay crop or 

early forage. Because it won’t have a chance to 

vernalize (be exposed to extended cold after germination), 

the rye can’t set seed and dies on its 

own within a few months in many areas. This 

provides good weed control in asparagus, says 

Rich de Wilde,Viroqua,Wis. (86). 

After drilling a large-seeded summer crop 

such as soybeans, try broadcasting rye. The cover 

grows well if it’s a cool spring, and the summer 

crop takes off as the temperature warms up. 

Secondary tillage or herbicides would be necessary 

to keep the rye in check and to limit the 

cover crop’s use of soil moisture. 


Killing & Controlling 

Nutrient availability concern. Rye grows and 

matures rapidly in spring, but its maturity date 

varies depending on soil moisture and temperature. 

Tall and stemmy, rye immobilizes N as it 

decomposes. The N tie-up varies directly with 

the maturity of the rye.Mineralization of N is very 

slow, so don’t count on rye’s overwintered N 

becoming available quickly. 

Killing rye early, while it’s still succulent, is 

one way to minimize N tie-up and conserve soil 

moisture. But spring rains can be problematic 

with rye, especially before an N- 

demanding crop, such as corn. 

Even if plentiful moisture hastens 

the optimal kill period, you 

still might get too much rain in 

the following weeks and have 

significant nitrate leaching, a 

Maryland study showed (84).Soil 

compaction also could be a 

problem if you’re mowing rye 

with heavy equipment. 

Late killing of rye can deplete soil moisture and 

could produce more residue than your tillage system 

can handle. For influencing corn yields in 

humid climates, however, summer soil-water conservation 

by cover crop residues often is more 

important than spring moisture depletion by growing 

cover crops,Maryland studies showed (62,64). 

Legume combo maintains yield. One way to 

offset yield reductions from rye’s immobilization 

of N would be to increase your N application. 

Here’s another option: Growing rye with a 

legume allows you to delay killing the covers by a 

few weeks and sustain yields, especially if the 

legume is at least half the mix. This gives the 

legume more time to fix N (in some cases doubling 

the N contribution) and rye more time to 

scavenge a little more leachable N. Base the kill 

date on your area’s normal kill date for a pure 

stand of the legume (84). 

A legume/rye mix generally increases total dry 

matter, compared with a pure rye stand. The 

higher residue level can conserve soil moisture. 

For best results, wait about 10 days after killing 

Rye is the best coolseason 

cover crop for 

scavenging N, typically 

carrying 25 to 50 lb. 

N/A over to spring. 

the covers before planting a crop. This ensures 

adequate soil warming,dry enough conditions for 

planter coulters to cut cleanly and minimizes 

allelopathic effects from rye residue (64, 84). If 

using a herbicide, you might need a higher spray 

volume or added pressure for adequate coverage. 

Kill before it matures. Tilling under rye usually 

eliminates regrowth, unless the rye is less than 12 

inches tall (302, 351). Rye often is plowed or 

disked in the Midwest when it’s about 20 inches 

tall (247). Incorporating the rye before it’s 18 in. 

high could decrease tie-up of 

soil N (302, 351). 

For best results when mowkilling 

rye, wait until it has 

begun flowering. A long-day 

plant, rye is encouraged to 

flower by 14 hours of daylight 

and a temperature of at least 40 

F. A sickle bar mower can give 

better results than a flail 

mower, which causes matting that can hinder 

emergence of subsequent crops (89). 

Mow-kill works well in the South after rye 

sheds pollen in late April (75). If soil moisture is 

adequate, you can plant cotton three to five days 

after mowing rye when row cleaners are used in 

reduced-tillage systems. 

Some farmers prefer to chop or mow rye by 

late boot stage, before it heads or flowers.“If rye 

gets away from you,you’d be better off baling it or 

harvesting it for seed,” cautions southern Illinois 

organic grain farmer Jack Erisman (24). He often 

overwinters cattle in rye fields that precede soybeans. 

But he prefers that soil temperature be at 

least 60 F before planting beans, which is too late 

for him to no-till beans into standing rye. 

“If rye is at least 24 inches tall, I control it with 

a rolling stalk chopper that thoroughly flattens 

and crimps the rye stems,” says Pennsylvania vegetable 

grower Steve Groff. “That can sometimes 

eliminate a burndown herbicide, depending on 

the rye growth stage and next crop.” 

A heavy duty rotavator set to only 2 inches 

deep does a good job of tilling rye, says Rich de 

Wilde,Viroqua,Wis. (86). 

RYE 69

Can’t delay a summer planting by a few weeks 

while waiting for rye to flower If early rye cultivars 

aren’t available in your area and you’re in 

Zone 5 or colder, you could plow the rye and use 

secondary tillage. Alternately, try a knockdown 

herbicide and post-emergent herbicide or spotspraying 

for residual weed control. 

Glyphosate provides a slow, yet effective, kill. 

Paraquat kills more rapidly and would be better 

when spring moisture is limited (82). For quicker 

growth of a subsequent crop such as corn or soybeans, 

leave the residue upright after killing 

(rather than flat). That hastens crop development—unless 

it’s a dry year—via warmer soil 

temperatures and a warmer seed zone, according 

to a three-year Ontario study (80,111). This rarely 

influences overall crop yield, however, unless you 

plant too early and rye residue or low soil temperature 

inhibits crop germination. 


Thick stands ensure excellent weed suppression. 

To extend rye’s weed-management 

benefits, you can allow its allelopathic effects to 

persist longer by leaving killed 

residue on the surface rather than 

incorporating it. Allelopathic 

effects usually taper off after 

about 30 days. After killing rye,it’s 

best to wait three to four weeks 

before planting small-seeded 

crops such as carrots or onions. If 

strip tilling vegetables into rye, be aware that rye 

seedlings have more allelopathic compounds 

than more mature rye residue.Transplanted vegetables, 

such as tomatoes, and larger-seeded 

species,especially legumes,are less susceptible to 

rye’s allelopathic effects (90). 

In an Ohio study, use of a mechanical undercutter 

to sever roots when rye was at mid- to late 

bloom—and leaving residue intact on the soil surface 

(as whole plants)—increased weed suppression, 

compared with incorporation or mowing. 

The broadleaf weed reduction was comparable to 

that seen when sickle-bar mowing, and better 

than flail-mowing or conventional tillage (70). 

Rye can effectively 

suppress weeds by 

shading, competition 

and allelopathy. 

If weed suppression is an important objective 

when planting a rye/legume mixture, plant early 

enough for the legume to establish well. Otherwise,you’re 

probably better off with a pure stand. 

Overseeding may not be cost-effective before a 

crop such as field corn,however. A mix of rye and 

bigflower vetch (a quick-establishing, self-seeding, 

winter-annual legume that flowers and 

matures weeks ahead of hairy vetch) can suppress 

weeds significantly more than rye alone, 

while also allowing higher N accumulations (85). 

“Rye can provide the best and cleanest mulch 

you could want if it’s cut or baled in spring before 

producing viable seed,” says Rich de Wilde (86). 

Rye can become a volunteer weed if tilled 

before it’s 8 inches high, however, or if seedheads 

start maturing before you kill it. Minimize 

regrowth by waiting until rye is at least 12 inches 

high before incorporating or by mow-killing after 

flowering but before grain fill begins. 

Insect pests rarely a problem. Rye can reduce 

insect pest problems in crop rotations, southern 

research suggests (369). In a number of mid- 

Atlantic locations, Colorado potato 

beetles have been virtually 

absent in tomatoes no-till transplanted 

into a mix of rye/vetch/ 

crimson clover, perhaps because 

the beetles can’t navigate 

through the residue (132). 

While insect infestations are 

rarely serious with rye, as with any cereal grain 

crop occasional problems occur. If armyworms 

have been a problem, for example, burning down 

rye before a corn crop could move the pests into 

the corn. Purdue Extension entomologists note 

many northeastern Indiana corn farmers reported 

this in 1997. Crop rotations and Integrated Pest 

Management can resolve most pest problems you 

might encounter with rye. 

Few diseases. Expect very few diseases when 

growing rye as a cover crop. A rye-based mulch 

can reduce diseases in some cropping systems. 

No-till transplanting tomatoes into a mix of 


ye/vetch/crimson clover,for example,consistently 

has been shown to delay the onset of early 

blight in several locations in the Northeast (132). 

The mulch presumably reduces soil splashing 

onto the leaves of the tomato plants. 

If you want the option of harvesting rye as a 

grain crop, use of resistant varieties, crop rotation 

and plowing under crop residues can minimize 

rust, stem smut and anthracnose. 

Other Options 

Quick to establish and easy to incorporate when 

succulent, rye can fill rotation gaps in reducedtillage, 

semi-permanent bed systems without 

increasing pest concerns or delaying crop plantings, 

a California study showed (173). 

Erol Maddox, a Hebron, Md. grower, takes 

advantage of rye’s relatively slow decomposition 

when double cropping. He likes transplanting 

spring cole crops into rye/vetch sod, chopping 

the cover mix at bloom stage and letting it lay 

until August, when he plants fall cole crops (199). 

Mature rye isn’t very palatable and provides 

poor-quality forage.It makes high quality hay or balage 

at boot stage, however, or grain can be ground 

and fed with other grains. Avoid feeding ergotinfected 

grain because it may cause abortions. 

Rye can extend the grazing season in late fall 

and early spring. It tolerates fall grazing or mowing 

with little effect on spring regrowth in many 

areas (166). Growing a mixture of more palatable 

cover crops (clovers, vetch or ryegrass) can 

encourage regrowth even further by discouraging 

overgrazing (268). 


Although rye’s extensive root system provides 

quick weed suppression and helps soil structure, 

don’t expect dramatic soil improvement from a 

single stand’s growth. Left in a poorly draining 

field too long,a rye cover could slow soil drainage 

and warming even further,delaying crop planting. 

It’s also not a silver bullet for eliminating herbicides.Expect 

to deal with some late-season weeds 

in subsequent crops (339). 


• Rye is more cold- and drought-tolerant than 

wheat. 

• Oats and barley do better than rye in hot 

weather. 

• Rye is taller than wheat and tillers less. It can 

produce more dry matter than wheat and a 

few other cereals on poor, droughty soils but 

is harder to burn down than wheat or triticale 

(191, 302). 

• Rye is a better soil renovator than oats (351), 

but brassicas and sudangrass provide deeper 

soil penetration (371). 

• Brassicas generally contain more N than rye, 

scavenge N nearly as well and are less likely 

to tie up N because they decompose more 

rapidly. 

SEED 

Cultivars. MERCED is a popular variety. AROO- 

STOOK is very cold-tolerant. ALBION is nematicidal. 

ABRUZZI is the earliest Southern variety. ELBON is 

slightly later than ABRUZZI but both are earlier 

than RYMOR. 


RYE 71

WINTER WHEAT 

Triticum aestivum 

Type: winter annual cereal grain 

Roles: prevent erosion, suppress 

weeds, scavenge excess nutrients, 

add organic matter 

Mix with: annual legumes or 

grasses, ryegrass 



Although typically grown as a cash grain, 

winter wheat can provide most of the 

cover crop benefits of other cereal crops, 

as well as a grazing option prior to spring tiller 

elongation. It’s less likely than barley or rye to 

become a weed and is easier to kill. Wheat also 

is slower to mature than some cereals, so there is 

no rush to incorporate it early in spring and risk 

compacting soil in wet conditions. 

Whether grown as a cover crop or for grain, 

winter wheat opens a rotation niche for underseeding 

a legume (such as red clover or sweetclover) 

for forage or nitrogen.It works well as part 

of a no-till or reduced-tillage crop rotation,and for 

weed control in potatoes grown with irrigation in 

semiarid regions. 

BENEFITS 

Erosion control. Winter wheat can serve as an 

overwintering cover crop for erosion control in 

most of the continental U.S. 

Nutrient catch crop. Wheat enhances cycling of 

N, P and K. A heavy N feeder in spring, wheat 

takes up N relatively slowly in autumn.It adds up, 

however. A September-seeded stand can absorb 

40 lb. N/A by December, a Maryland study 

showed (30). As an overwintering cover rather 

than a grain crop, wheat wouldn’t need fall or 

spring fertilizer. 

A wheat stand can take up 0.5 to 0.7 lb. of P2O5 

for each bushel of grain produced,but nearly twothirds 

of it (20 to 25 pounds per acre for a 50- 

bushel wheat crop) is absorbed before boot stage. 

Wheat also can take up 1.5 to 2 lb. K2O for each 

bushel produced. About 90 percent of that is 

taken up before wheat heads, and more than 80 

percent of the K is recycled if the stems and 

leaves aren’t removed from the field at harvest. 

All the nutrients are recycled when wheat is 

managed as a cover crop, giving it a role in scavenging 

excess nitrogen. 

“Cash and Cover” crop. Winter wheat provides 

a cash-grain option while also creating a niche in 

a corn>soybean or similar rotation for a second 

cover crop, such as a winter annual legume. For 

example: 

• In the Cotton Belt, wheat and crimson clover 

would be a good mix. 

• In Hardiness Zone 6 and parts of Zone 7, 

plant hairy vetch after wheat harvest, giving the 

legume plenty of time to establish in fall. Vetch 

growth in spring may provide most of the N necessary 

for heavy feeders such as corn, or all of the 

N for sorghum, in areas northward to southern 

Illinois, where early spring warm-up allows time 

for development. 

• In much of Zone 7,cowpeas would be a good 

choice after wheat harvest in early July or before 

planting winter wheat in fall (88). 


• In the Corn Belt and northern U.S.,undersow 

red clover or frostseed sweetclover into a wheat 

nurse crop if you want the option of a year of hay 

before going back to corn. Or, kill a wheat cover 

grown with a winter annual such as hairy vetch 

before vetch reaches peak N, and still make your 

area’s usual planting date for corn. Winterkilled 

crimson or berseem clover are other options. 

With or without underseeding a legume or 

legume-grass mix, winter wheat provides great 

grazing and nutritional value and can extend the 

grazing season. In Zone 8 and warmer, you also 

have a dependable double-crop option. See Wheat 

Boosts Income and Soil Protection (p. 74). 

Weed suppressor. As a fall-sown cereal, wheat 

competes well with most weeds once it is established 

(51). Its rapid spring growth also helps 

choke weeds, especially with an underseeded 

legume competing for light and surface nutrients. 

Soil builder and organic matter source. 

Wheat is a plentiful source of straw and stubble. 

Although it generally produces less than rye or 

barley, the residue can be easier to manage and 

incorporate. Wheat’s fine root system also 

improves topsoil tilth. 

When selecting a locally adapted variety for use 

as a cover crop, you might not need premium 

seed. While a few cultivars, such as POCAHONTAS, 

provide slightly more biomass in early growth 

stages, first-year data from a Maryland study of 25 

wheat cultivars showed no major differences in 

overall biomass production at maturity (66). If 

weed control is important in your system,look for 

a regional cultivar that can produce early spring 

growth.To scavenge N, select a variety with good 

fall growth before winter dormancy. 

MANAGEMENT 


Wheat prefers well-drained soils of medium texture 

and moderate fertility. It tolerates poorly 

drained, heavier soils better than barley or oats, 

but flooding can easily drown a wheat stand. Rye 

may be a better choice for some poor soils. 

WINTER WHEAT (Triticum aestivum) 

Biomass production and N uptake are fairly 

slow in autumn. Tillering resumes in late winter/early 

spring and N uptake increases quickly 

during stem extension. 

Adequate but not excessive N is important during 

wheat’s early growth stages (prior to stem 

growth) to ensure adequate tillering and root 

growth prior to winter dormancy. In low-fertility 

or light-textured soils, consider a mixed seeding 

with a legume (60). Another alternative could be 

adding up to 50 pounds of starter N per acre,especially 

on low-N soils if you’ll be killing the wheat in 

spring before a heavy-feeding crop such as potatoes 

and are relying on a thick,overwintering stand 

for weed control. See Wheat Offers High Value 

Weed Control, Too (p. 75). Too much N, however, 

can produce rank, succulent plants that are 

susceptible to winterkill, disease or lodging. 

A firm seedbed helps reduce winterkill of 

wheat. Minimize tillage in semiarid regions to 

avoid pulverizing topsoil (297) and depleting soil 

moisture (82). 

Elayne Sears 

WINTER WHEAT 73

Wheat Boosts Income and Soil Protection 

Wheat is an ideal fall cover crop that can 

double as a cash crop, cotton farmer Max 

Carter has found.“It’s easier to manage than 

rye, still leaves plenty of residue to keep 

topsoil from washing away—and is an 

excellent double crop,” says Carter. 

The southeastern Georgia farmer no-till drills 

winter wheat at 2 bushels per acre right after 

cotton harvest, without any seedbed 

preparation.“It gives a good, thick stand,”he says. 

“We usually get wheat in by Thanksgiving, 

but as long as it’s planted by Christmas, I 

know it’ll do fine,” he adds.After drilling 

wheat, Carter goes back and mows the cotton 

stalks to leave some field residue until the 

wheat establishes. 

He pays about 7 to 14 cents per pound for 

seed, depending on whether he chooses to 

use uncleaned or premium, cleaned seed. 

Disease or pests rarely have been a problem, 

he notes. 

“It’s a very easy system, with wheat always 

serving as a fall cover crop for us. It builds soil 

and encourages helpful soil microorganisms. 

It can be grazed, or we can burn some down 

in March for planting early corn or peanuts 

anytime from March to June,” he says. 

For a double crop before 2-bale-an-acre 

cotton, Carter irrigates the stand once in 

spring with a center pivot and harvests 45- 

to 60-bushel wheat by the end of May.“The 

chopper on the rear of the combine puts the 

straw right back on the soil as an even blanket 

and we’re back planting cotton on June 1.” 

“It sure beats idling land and losing 

topsoil.” 

Winter annual use. Seed from late summer to 

early fall in Zone 3 to 7—a few weeks earlier than 

a rye or wheat grain crop—and from fall 

to early winter in Zone 8 and warmer. If your 

cover crop planting is delayed, consider sowing 

rye instead. 

Drill 60 to 120 lb./A (1 to 2 bushels) into a firm 

seedbed at a 1 /2- to 1 1 /2-inch depth or broadcast 60 

to 160 lb./A (1 to 2.5 bushels) and disk lightly or 

cultipack to cover. Plant at a high rate if seeding 

late, when overseeding into soybeans at the leafyellowing 

stage,when planting into a dry seedbed 

or when you require a thick, weed-suppressing 

stand. Seed at a low to medium rate when soil 

moisture is plentiful (51). 

After cotton harvest in Zone 8 and warmer, 

no-till drill 2 bushels of wheat per acre without 

any seedbed preparation. With irrigation or in 

humid regions, you could harvest 45- to 60- 

bushel wheat, then double crop with soybeans, 

cotton or another summer crop. See Wheat 

Boosts Income and Soil Protection (above).You 

also could overseed winter wheat prior to cotton 

defoliation and harvesting (287). 

Another possibility for Zone 7 and cooler:Plant 

full-season soybeans into wheat cover crop 

residue, and plant a wheat cover crop after bean 

harvest (60). 

Mixed seeding or nurse crop. At low to medium 

rates (300), winter wheat is an excellent nurse 

crop for frostseeding red clover (at 8 to 12 lb./A), 

or sweetclover (at 4 to 12 lb./A). In the Corn Belt, 

the legume usually would be sown in winter or 

before wheat’s vegetative growth resumes in 

spring. If you sow sweetclover in fall with winter 

wheat, it could outgrow the wheat. If you want a 

grain option, that could make harvest difficult. 

Spring annual use. Spotty overwintering of winter 

wheat in your area Or no time to fall-seed it 

Although it’s not a common practice, you can 

spring-seed winter wheat as a weed-suppressing 

companion crop or early forage. It won’t have a 

chance to vernalize (be exposed to extended cold 

after germination), so it usually dies on its own 

within a few months,without setting seed.By sowing 

when field conditions permit in early spring, 


Wheat Offers High-Value Weed Control, Too 

Pairing a winter wheat cover crop with a 

reduced herbicide program could provide 

excellent weed control in potatoes grown 

on light soils in irrigated, semiarid regions, 

research in the inland Pacific Northwest 

suggests.A SARE-funded study in the early 

1990s showed that winter wheat provided 

effective competition against annual 

weeds that infest irrigated potato fields in 

Washington, Oregon and Idaho. However, 

potato yield and quality reductions 

outweighed cost savings, that study’s 

economic analysis showed. 

Banding herbicide over the row when 

planting potatoes improves the system’s 

effectiveness, subsequent research shows, says 

project coordinator Dr. Charlotte Eberlein at the 

University of Idaho’s Aberdeen Research and 

Extension Center. “In our initial study, we were 

effectively no-tilling potatoes into the Roundupkilled 

wheat,”says Eberlein.“Now we kill the 

cover crop and plant potatoes with a regular 

potato planter, which rips the wheat out of the 

potato row.”A grower then can band a herbicide 

mixture over the row and depend on the wheat 

mulch to control between-row weeds. 

“If you have sandy soil to start with and 

can kill winter wheat early enough to reduce 

water-management concerns for the potatoes, 

the system works well,” says Eberlein. 

“Winter rye would be a slightly better cover 

crop for suppressing weeds in a system like 

this,” she notes.“Volunteer rye, however, is a 

serious problem in wheat grown in the West, 

and wheat is a common rotation crop for 

potato growers in the Pacific Northwest.” 

She recommends drilling winter wheat at 

90 lb./A into a good seedbed, generally in mid- 

September in Idaho.“In our area, growers can 

deep rip in fall, disk and build the beds (hills), 

then drill wheat directly into the beds,” she 

says. Some starter N (50 to 60 lb./A) can help 

the wheat establish. If indicated by soil testing, 

P or K also would be fall-applied for the 

following potato crop. 

The wheat usually does well and shows 

good winter survival. Amount of spring rainfall 

and soil moisture and the wheat growth rate 

determine the optimal dates for killing wheat 

and planting potatoes. 

Some years, you might plant into the wheat 

and broadcast Roundup about a week later. 

Other years, if a wet spring delays potato 

planting, you could kill wheat before it gets 

out of hand (before the boot stage), then 

wait for better potato-planting conditions. 

Moisture management is important, 

especially during dry springs, she says.“We 

usually kill the wheat from early to mid May— 

a week or two after planting potatoes.That’s 

soon enough to maintain adequate moisture 

in the hills for potatoes to sprout.” 

An irrigation option ensures adequate soil 

moisture—for the wheat stand in fall or the 

potato crop in spring, she adds.“You want a 

good, competitive wheat stand and a vigorous 

potato crop if you’re depending on a banded 

herbicide mix and wheat mulch for weed 

control,” says Eberlein.That combination 

gives competitive yields, she observes, based 

on research station trials. 

Full-scale on-farm studies and economic 

analyses are next on the project agenda and 

could lead to greater use of winter wheat as 

a cover crop for weed control, nutrient cycling 

and other benefits. 

within a couple months you could have a 6- to 

10-inch tall cover crop into which you can no-till 

plant soybeans. You might not need a burndown 

herbicide, either. 

Early planting of spring wheat, with or 

without a legume companion, is an option, 

especially if you have a longer rotation niche 

available. 

WINTER WHEAT 75


You needn’t spring fertilize a winter wheat stand 

being grown as a cover crop rather than a grain 

crop. As with any overwintering small grain crop, 

however,you will want to ensure the wheat stand 

doesn’t adversely affect soil moisture or nutrient 

availability for the following crop. 

Killing 

Kill wheat with a grass herbicide in spring, or by 

plowing, disking or mowing before seedheads 

mature. 

There is no need to rush to kill 

wheat in spring as is sometimes 

required for rye. That’s one reason 

vegetable grower Will Stevens, 

Shoreham, Vt., prefers wheat to 

rye as a winter cover on his heavy, 

clay-loam soils.The wheat goes to 

seed slower and can provide more 

leaf matter than an earlier killing 

of rye would, he’s found.With rye, he has to disk 

two to three weeks earlier in spring to incorporate 

the biomass, which can be a problem in wet 

conditions.“I only chisel plow wheat if it’s really 

rank,” he notes. 


Wheat is less likely than rye or barley to become 

a weed problem in a rotation, but is a little more 

susceptible than rye or oats to insects and disease. 

Managed as a cover crop, wheat rarely 

poses an insect or disease risk. Diseases can be 

Wheat is less likely 

than barley or rye to 

become a weed, and 

is easier to kill. 

more of a problem the earlier wheat is planted in 

fall, especially if you farm in a humid area. 

Growing winter wheat could influence the 

buildup of pathogens and affect future smallgrain 

cash crops, however. Use of resistant varieties 

and other Integrated Pest Management 

practices can avoid many pest problems in 

wheat grown for grain.If wheat diseases or pests 

are a major concern in your area, rye or barley 

might be a better choice as an overwintering 

cover crop that provides a grain option, despite 

their lower yield. 

Other Options 

Choosing wheat as a small-grain 

cover crop offers the flexibility 

in late spring or early summer to 

harvest a grain crop. Spring management 

is essential for the grain 

crop option.A good resource for 

grain production techniques, 

used extensively in writing this chapter, is Best 

Management Practices for Wheat, listed under 



Avoid grazing livestock in wheat stands suffering 

from fungal diseases such as scab, which can 

produce substances toxic to livestock, especially 

nonruminants. 



BUCKWHEAT 

Fagopyrum esculentum 

Type: summer or cool-season 

annual broadleaf grain 

Roles: quick soil cover, weed 

suppressor, nectar for pollinators 

and beneficial insects, topsoil 

loosener, rejuvenator for lowfertility 

soils 

Mix with: sorghum-Sudangrass 

hybrids, sunn hemp 



summer or 

cool-season annual 

too dry, cool 

Buckwheat is the speedy short-season cover 

crop. It establishes, blooms and reaches 

maturity in just 70 to 90 days. Then its 

residue breaks down quickly. Buckwheat suppresses 

weeds and attracts beneficial insects and 

pollinators with its abundant blossoms. It is easy 

to kill, and reportedly extracts soil phosphorus 

from soil better than most grain-type cover crops. 

Buckwheat thrives in cool, moist conditions 

but it is not frost tolerant. Even in the South, it is 

not grown as a winter annual. Buckwheat is not 

particularly drought tolerant, and readily wilts 

under hot, dry conditions. Its short growing season 

may allow it to avoid droughts, however. 

BENEFITS 

Quick cover. Few cover crops establish as rapidly 

and as easily as buckwheat. Its rounded pyramid-shaped 

seeds germinate in just three to five 

days. Leaves up to 3 inches wide can develop 

within two weeks to create a relatively dense,soilshading 

canopy, though not as dense as corn or 

soybeans.Buckwheat typically produces only 2 to 

3 tons of dry matter per acre,but it does so quickly—in 

just six to eight weeks in the mild, temperate 

fields of central Pennsylvania in USDA 

Hardiness Zone 5-6 (206).Buckwheat residue also 

decomposes quickly, releasing nutrients to the 

next crop. 

Weed suppressor. Buckwheat’s strong weedsuppressing 

ability makes it ideal for smothering 

warm-season annual weeds. It’s also planted after 

intensive, weed-weakening tillage to crowd out 

perennials.A mix of tillage and successive dense 

seedings of buckwheat can effectively suppress 

Canada thistle, sowthistle, creeping jenny, leafy 

spurge, Russian knapweed and perennial peppergrass 

(206).While living buckwheat may have an 

allelopathic weed-suppressing effect (291),its primary 

impact on weeds is through shading and 

competition. 

Phosphorus scavenger. Buckwheat is believed 

to be effective in taking up phosphorus and some 

minor nutrients (possibly including calcium) that 

are otherwise unavailable to crops, then releasing 

these nutrients to later crops as the residue 

breaks down. The roots of the plants produce 

mild acids that free these nutrients from other 

compounds. This effect aids in activating slowreleasing 

organic fertilizers, such as rock phosphate. 

Buckwheat’s dense, fibrous roots cluster in 

BUCKWHEAT 77

Nectar source. Buckwheat’s shallow white blossoms 

attract beneficial insects that attack or parasitize 

aphids, mites and other pests.These beneficials 

include hover flies (Syrphidae), predatory 

wasps, minute pirate bugs, insidious flower bugs, 

tachinid flies and lady beetles. Flowering may 

start within three weeks of planting and continue 

for up to 10 weeks. 


BUCKWHEAT (Fagopyrum esculentum) 

the top 10 inches of soil, providing an extensive 

root surface area for nutrient uptake. 

Thrives in poor soils. Buckwheat performs better 

than cereal grains on low-fertility soils and 

soils with high levels of decaying organic matter. 

That’s why it was often the first crop planted on 

cleared land during the settlement of woodland 

areas and is still a good first crop for rejuvenating 

over-farmed soils. However, buckwheat does not 

do well in compacted, droughty or excessively 

wet soils. 

Quick regrowth. Buckwheat will regrow after 

mowing if cut before it reaches 25 percent 

bloom. It also can be lightly tilled after the midpoint 

of its long flowering period to reseed a second 

crop. Some growers bring new land into 

production by raising three successive buckwheat 

crops this way. 

Soil conditioner. Buckwheat’s abundant, fine 

roots leave topsoil loose and friable after only minimal 

tillage, making it a great mid-summer soil conditioner 

preceding fall crops in temperate areas. 

Late-season nurse crop. Due to its quick, 

aggressive start, buckwheat sees only limited 

action as a nurse crop.It’s sometimes used to protect 

late-fall plantings of slow-starting, winterhardy 

legumes wherever freezing temperatures 

are sure to kill the buckwheat. 

MANAGEMENT 

Buckwheat prefers light to medium, well-drained 

soils—sandy loams, loams, and silt loams. It performs 

poorly on heavy,wet soils or soils with high 

levels of limestone. Buckwheat grows best in 

cool, moist conditions, but is not frost-tolerant. It 

is also not drought tolerant. Extreme afternoon 

heat will cause wilting, but plants bounce back 

overnight. 

Establishment 

Plant buckwheat after all danger of frost. In 

untilled, minimally tilled or clean-tilled soils, drill 

50 to 60 lb./A at 1 /2 to 1 1 /2 inches deep in 6 to 8- 

inch rows. Use heavier rates for a quicker 

canopy. For a fast smother crop, broadcast up to 

96 lb./A (2 bu./A) onto a firm seedbed and incorporate 

with a harrow, tine weeder, disk or field 

cultivator. Overall vigor is usually better in 

drilled seedings. As a nurse-crop for slow-growing, 

winter annual legumes planted in late summer 

or fall, seed at one-quarter to one-third of 

the normal rate. 

Buckwheat compensates for lower seeding 

rates by developing more branches per plant 

and more seeds per blossom. However, skimping 

too much on seed makes stands more vulnerable 

to early weed competition until the canopy fills 

in. Using cleaned, bin-run or even birdseed-grade 

seed can lower establishment costs, but increases 

the risk of weeds. As denser stands mature, 

stalks become spindly and are more likely to 

lodge from wind or heavy rain. 


Rotations 

Buckwheat is used most commonly as a mid-summer 

cover crop to suppress weeds and replace 

bare fallow. In the Northeast and Midwest, it is 

often planted after harvest of early vegetable 

crops, then followed by a fall vegetable, winter 

grain,or cool-season cover crop. 

In many areas, it can be planted 

following harvest of winter 

wheat or canola. 

In parts of California, buckwheat 

grows and flowers 

between the killing of winter 

annual legume cover crops in 

spring and their re-establishment 

in fall. Some California 

vineyard managers seed 3-foot strips of buckwheat 

in row middles, alternating it and another 

summer cover crop, such as sorghum-Sudangrass. 

Buckwheat is sensitive to herbicide residues 

from previous crops, especially in no-till 

seedbeds. Residue from trifluralin and from triazine 

and sulfonylurea herbicides have damaged 

or killed buckwheat seedlings (57). When in 

doubt, sow and water a small test plot of the fastgerminating 

seed to detect stunting or mortality. 


Few pests or diseases bother buckwheat. Its most 

serious weed competitors are often small grains 

from preceding crops, which only add to the 

cover crop biomass. Other grass weeds can be a 

problem, especially in thin stands.Weeds also can 

increase after seed set and leaf drop. Diseases 

include a leaf spot caused by the fungus 

Ramularia and Rhizoctonia root rot. 

Other Options 

Plant buckwheat as an emergency cover crop to 

protect soil and suppress weeds when your main 

crop fails or cannot be planted in time due to 

unfavorable conditions. 

To assure its role as habitat for beneficial 

insects, allow buckwheat to flower for at least 20 

days—the time needed for minute pirate bugs to 

produce another generation. 

Buckwheat germinates 

and grows quickly, 

producing 2 to 3 tons 

of dry matter in just 

6 to 8 weeks. 

Buckwheat can be double cropped for grain 

after harvesting early crops if planted by mid-July 

in northern states or by early August in the South. 

It requires a two-month period of relatively cool, 

moist conditions to prevent blasting of the blossoms. 

There is modest demand for organic and 

specially raised food-grade 

buckwheat in domestic and 

overseas markets.About 70,000 

acres are grown in the U.S., 

with prices typically around 

10 cents/lb. Exporters usually 

specify variety, so investigate 

before planting buckwheat for 

grain. 


To get optimal biomass while preventing buckwheat 

from becoming a weed in following crops, 

kill within 7 to 10 days after flowering begins, 

before the first seeds begin to harden and turn 

brown. Earliest maturing seed can shatter before 

plants finish blooming. Some seed may overwinter 

in milder regions. 

Buckwheat can harbor insect pests including 

Lygus bugs,tarnished plant bugs and Pratylynchus 

penetrans root lesion nematodes (204). 


• Buckwheat has only about half the root mass 

as a percent of total biomass as small grains 

(294). Its succulent stems break down 

quickly, leaving soils loose and vulnerable 

to erosion, particularly after tillage. Plant a 

soil-holding crop as soon as possible. 

• Buckwheat is nearly three times as effective 

as barley in extracting phosphorus, and 

more than 10 times more effective than 

rye—the poorest P scavenger of the cereal 

grains (294). 

• As a cash crop, buckwheat uses only half as 

much soil moisture as soybeans (242). 


BUCKWHEAT 79

SORGHUM-SUDANGRASS HYBRIDS 

Sorghum bicolor X S. bicolor 

var. sudanese 

Also called: Sudex, Sudax 

(DeKalb reg. brand) 

Type: summer annual grass 

Roles: soil builder, weed and 

nematode suppressor, subsoil 

loosener 

Mix with: buckwheat, sesbania, 

sunnhemp, forage soybeans or 

cowpeas 



summer annual 

year-round crop 

summer annual irrigated 

limited by cool temps. 

Sorghum-sudangrass hybrids are unrivaled for 

adding organic matter to worn-out soils. 

These tall, fast-growing, heat-loving summer 

annual grasses can smother weeds,suppress some 

nematode species and penetrate compacted subsoil 

if mowed once.Seed cost is modest.Followed 

by a legume cover crop, sorghum-sudangrass 

hybrids are a top choice for renovating overfarmed 

or compacted fields. 

The hybrids are crosses between forage-type 

sorghums and sundangrass. Compared with corn, 

they have less leaf area,more secondary roots and 

a waxier leaf surface, traits that help them withstand 

drought (302). Like corn, they require good 

fertility—and usually added nitrogen—for best 

growth.Compared with sudangrass,these hybrids 

are taller, coarser and more productive. 

Forage-type sorghum plants are larger, leafier 

and mature later than grain sorghum plants. 

Compared with sorghum-sudangrass hybrids,they 

are shorter, less drought tolerant, and don’t 

regrow as well (292). Still, forage sorghums as 

well as most forms of sudangrass can be used in 

the same cover-cropping roles as sorghum-sudangrass 

hybrids. All sorghum- and sudangrass-related 

species produce compounds that inhibit certain 

plants and nematodes. They are not frost 

tolerant, and should be planted after the soil 

warms in spring or in summer at least six weeks 

before first frost. 

BENEFITS 

Biomass producer. Sorghum-sudangrass grows 

5 to 12 feet tall with long,slender leaves,stalks up 

to one-half inch in diameter and aggressive root 

systems. These features combine to produce 

ample biomass, usually about 4,000 to 5,000 lb. 

DM/A. Up to 18,000 lb. DM/A has been measured 

with multiple cuttings on fertile, well-watered 

soil. 

Subsoil aerator. Mowing whenever stalks reach 

3 to 4 feet tall increases root mass five to eight 

times compared with unmowed stalks, and forces 

the roots to penetrate deeper. 

In addition, tops grow back green and vegetative 

until frost and tillering creates up to six new, 

thicker stalks per plant. A single mowing on 

New York muck soils caused roots to burrow 10 

to 16 inches deep compared to 6 to 8 inches deep 

for unmowed plants (224). The roots of mowed 


plants fractured subsoil compaction with wormhole-like 

openings that improved surface 

drainage. However, four mowings at shorter 

heights caused plants to behave more like a grass 

and significantly decreased the mass, depth and 

diameter of roots (223). 

Weed suppressor. When sown at higher rates 

than normally used for forage crops, sorghumsudangrass 

hybrids make an effective smother 

crop. Their seedlings, shoots, leaves and roots 

secrete allelopathic compounds that suppress 

many weeds. The main root exudate, sorgoleone, 

is strongly active at extremely low concentrations, 

comparable to those of some 

synthetic herbicides (305). As early as five days 

after germination, roots begin secreting this allelochemical, 

which persists for weeks and has visible 

effects on lettuce seedlings even at 10 parts 

per million (362). 

Sorghum-sudangrass hybrids suppress such 

annual weeds as velvetleaf, large crabgrass, barnyardgrass 

(97,245),green foxtail,smooth pigweed 

(146), common ragweed, redroot pigweed and 

purslane (257).They also suppressed pine (171) 

and redbud tree seedlings in nursery tests (117). 

The residual weed-killing effects of these allelochemicals 

increases when sorghum-sudangrass 

hybrids are treated with the herbicides sethoxydim, 

glyphosate or paraquat, in descending order 

of magnitude (109). 

Nematode and disease fighter. Planting 

sorghum-sudangrass hybrids instead of a host 

crop is a great way to disrupt the life cycles of 

many diseases, nematodes and other pests. For 

example, when sorghum-sudangrass or sorghum 

alone were no-tilled into endophyte-infected fescue 

pastures in Missouri that had received two 

herbicide applications, the disease was controlled 

nearly 100 percent. No-till reseeding with endophyte-free 

fescue completed this cost-effective 

renovation that significantly improved the rate of 

gain of yearling steers (11). 

Renews farmed-out soils. The combination of 

abundant biomass production, subsoiling root 

SORGHUM-SUDANGRASS (Sorghum bicolor X 

S. bicolor var. sudanese 

systems, and weed and nematode suppression 

can produce dramatic results. 

On a low-producing muck field in New York 

where onion yields had fallen to less than a third 

of the local average, a single year of a dense planting 

of sorghum-sudangrass hybrid restored the 

soil to a condition close to that of newly cleared 

land (174). 

Widely adapted. Sorghum-sudangrass hybrids 

can be grown throughout the U.S. wherever rainfall 

is adequate and soil temperature reaches 65 F 

to 70 F at least two months before frost. Once 

established, they can withstand drought by going 

nearly dormant. Sorghum-sudangrass hybrids 

tolerate pH as high as 9.0, and are often used in 

rotation with barley to reclaim alkaline soil (350). 

They tolerate pH as low as 5.0 (306). 

Quick forage. Sorghum-sudangrass is prized as 

summer forage. It can provide quick cover to prevent 

weeds or erosion where legume forages have 

been winterkilled or flooded out. Use care 

because these hybrids and other sorghums can 

produce prussic acid poisoning in livestock. 

Grazing is riskiest when plants are young (up to 

24 inches tall), drought stressed or killed by frost. 

Toxicity danger varies between cultivars. 


SORGHUM-SUNDANGRASS HYBRIDS 81

MANAGEMENT 

Establishment 

Plant sorghum-sudangrass when soils are warm 

and moist, usually at least two weeks after the 

prime corn-planting date for your area. It will tolerate 

low-fertility, moderate acidity and high alkalinity, 

but prefers good fertility and near-neutral 

pH (302). Standard biomass production usually 

requires 75 to 100 lb. N/A . 

With sufficient surface moisture, broadcast 40 

to 50 lb./A, or drill 35 to 40 lb./A as deep as 2 

inches to reach moist soil.These rates provide a 

quicker canopy to smother weeds than lower 

rates used for forage production, 

but they require mowing 

or grazing to prevent lodging. 

Herbicide treatment or a pass 

with a mechanical weeder may 

be necessary if germination is 

spotty or perennial weeds are 

a problem. New York on-farm tests show that a 

stale seedbed method—tilling,then retilling to kill 

the first flush of weeds just before planting— 

provides effective weed control (224). 

Warm season mixtures. Plant sorghum-sudangrass 

in cover crop mixtures with buckwheat or 

with the legumes sesbania (Sesbania exaltata), 

sunnhemp (Crotolaria juncea), forage soybeans 

(Glycine max) or cowpeas (Vigna unguiculata). 

Broadcast these large-seeded cover crops with the 

sorghum-sudangrass, then incorporate about 1 

inch deep.Fast-germinating buckwheat helps suppress 

early weeds. Sorghum-sudangrass supports 

the sprawling sesbania, forage soybeans and cowpeas. 

Sunnhemp has an upright habit, but could 

compete well for light if matched with a 

sorghum-sudangrass cultivar of a similar height. 


Plants grow very tall (up to 12 feet),produce tons 

of dry matter and become woody as they mature. 

This can result in an unmanageable amount of 

tough residue that interferes with early planting 

the following spring (223). 

Mowing or grazing when stalks are 3 to 4 feet 

tall encourages tillering and deeper root growth, 

These heat-loving plants 

are unrivaled for adding 

organic matter to soils. 

and keeps regrowth vegetative and less fibrous 

until frost. For mid-summer cuttings, leave at least 

6 inches of stubble to ensure good regrowth and 

continued weed suppression. Delayed planting— 

within seven weeks of frost—makes mowing 

unnecessary and still allows for good growth 

before winterkilling (223, 224, 302). 

Disking while plants are still vegetative will 

speed decomposition. Make several passes with a 

heavy disk or combination tillage tool to handle 

the dense root masses (223).Sicklebar mowing or 

flail chopping before tillage will reduce the number 

of field operations required to incorporate the 

crop and speed decomposition. Sicklebars cut 

more cleanly but leave the 

stalks whole. Using a frontmounted 

flail chopper avoids 

the problem of skips where 

tractor tires flatten the plants, 

putting them out of reach of a 

rear-mounted chopper. 

Any operations that decrease the residue size 

shortens the period during which the decomposing 

residue will tie up soil nitrogen and hinder 

early planted crops. Even when mowed, residue 

will become tough and slower to break down if 

left on the surface. 

Flail chopping after frost or killing the cover 

crop with herbicide will create a suitable mulch 

for no-till planting, preserving soil life and soil 

structure in non-compacted fields. 


Weeds. Use sorghum-sudangrass to help control 

nutsedge infestations, suggests Cornell Extension 

IPM vegetable specialist John Mishanec. Allow 

the nutsedge to grow until it’s about 4 to 5 inches 

tall, about mid-June in New York. Kill the nutsedge 

with herbicide, then plant the weed-smothering 

hybrid. 

Beneficial habitat. Some related sorghum cultivars 

harbor beneficial insects such as seven-spotted 

lady beetles (Coccinella septempunctata) and 

lacewings (Chrysopa carnea) (350). 

Nematodes. Sorghum-sudangrass hybrids and 

other sorghum-related crops and cultivars sup- 


press some species of nematodes. Specific cultivars 

vary in their effectiveness on different races 

of nematodes. These high-biomass-producing 

crops have a general suppressive effect due to 

their organic matter contributions. But they also 

produce natural nematicidal compounds that 

chemically suppress some nematodes, many 

studies show. 

Timing of cutting and tillage is very important to 

the effectiveness of nematode suppression. The 

cover crop needs to be tilled before frost while it is 

still green. Otherwise, the 

nematicidal effect is lost. For 

maximum suppression of soilborne 

diseases, cut or chopped 

Sudangrass must be well incorporated 

immediately (248). 

In an Oregon potato trial, 

TRUDAN 8 sudangrass controlled 

Columbia root-knot nematodes (Meloidogoyne 

Chitwoodi), a serious pest of many vegetable 

crops. Control extended throughout the zone of 

residue incorporation. The cover crop’s effect 

prevented upward migration of the nematodes 

into the zone for six weeks,working as well as the 

nematicide ethoprop. Both treatments allowed 

infection later in the season (227). 

In the study, TRUDAN 8 sudangrass and the 

sorghum-sudangrass hybrid cultivars SORDAN 79 

and SS-222 all reduced populations of root-knot 

nematodes. These cultivars are poor nematode 

hosts and their leaves—not roots—have a nematicidal 

effect. TRUDAN 8 should be used if the crop 

will be grazed due to its lower potential for prussic 

acid poisoning. The sorghum-sudangrass 

cultivars are useful if the cover crop is intended 

for anti-nematicidal effects only (227). In other 

Oregon and Washington trials,the cover crop suppression 

required supplemental chemical nematicide 

to produce profitable levels of U.S. No. 1 

potatoes (227). These same sudangrass and 

sorghum-sudangrass hybrid cultivars failed to 

show any significant nematicidal effects in a later 

experiment in Wisconsin potato fields (198). 

When faced with infestations of the nematodes 

Meloidogoyne incognita and M. arenaria, 

Oswego,N.Y.,onion grower Dan Dunsmoor found 

that a well-incorporated sorghum-sudangrass 

These plants produce 

chemicals that inhibit 

certain weeds and 

nematodes. 

cover crop with a seed cost of $32.50/A was 

more effective than fumigation costing $300 to 

$600/A. Further, the nematicidal effect continued 

into the next season, while the conditions a year 

after fumigation seemed worse than before the 

application. He reports that the sorghum-sudangrass 

cover crop also controls onion maggot, 

thrips and Botrytis leaf blight (174). 

Insect pests. Chinch bug (Blissus leucopterus), 

sorghum midge (Contarinia sorghicola), corn leaf 

aphid (Rhopalosiphum maidis), 

corn earworm (Heliothis zea), 

greenbugs (Schizaphis graminum) 

and sorghum webworm 

(Celama sorghiella) sometimes 

attack sorghum-sudangrass hybrids. 

Early planting helps control the 

first two pests, and may reduce 

damage from webworms. Some cultivars and 

hybrids are resistant to chinch bugs and some 

biotypes of greenbugs (302). In Georgia, some 

hybrids hosted corn leaf aphid,greenbug,southern 

green stinkbugs (Nezara viridula) and leaffootted 

bug (Leptoglossus phyllopus). 

Crop Systems 

There are several strategies for reducing nitrogen 

tie-up from residue: 

• Interplant a legume with the sorghum-sudangrass 

hybrid. 

• Plant a legume cover crop after the sorghumsudangrass 

hybrid, in either late summer or 

the following spring. 

• Apply nitrogen fertilizer or some other N 

source at incorporation and leave the land 

fallow for a few months when soil is not 

frozen to allow decomposition of the residue. 

If you kill the cover crop early enough in fall, 

the residue will partially break down before cold 

temperatures slow biological action (302). Where 

possible, use sorghum-sudangrass ahead of laterplanted 

crops to allow more time in spring for 

residue to decompose. 

Planting sorghum-sudangrass every third year 

on New York potato and onion farms will rejuvenate 

soil, suppress weeds and may suppress soil 

pathogens and nematodes. Working a legume into 


Summer Covers Relieve Compaction 

A summer planting of sudangrass was the 

best single-season cover crop for relieving 

soil compaction in vegetable fields, a 

team of Cornell researchers found.Yellow 

mustard, HUBAM annual white sweetclover 

and perennial ryegrass also were effective 

to some extent in the multi-year study.“But 

sudangrass has proven the most promising 

so far,” says project coordinator David Wolfe. 

“It has shown the fastest root growth.” 

Sudangrass is particularly effective when 

it is mowed once during the season,Wolfe 

adds. Mowing strengthens its deep, 

penetrating root system while the aboveground 

biomass adds to soil organic matter. 

Farmers and researchers have long 

known that alfalfa’s deep root system is a 

great compaction-buster. But most vegetable 

growers can’t afford to remove land from 

production for two to three years to 

grow it, notes Wolfe. Many also lack the 

equipment to subsoil their fields, which 

is often only a temporary solution, at best. 

That’s why Wolfe geared his study to 

identify covers that can produce results 

in a single season. In the case of heatloving 

sudangrass, it also may be possible 

to squeeze a spring or fall cash crop into 

the rotation while still growing the cover 

during summer. 

Heavy equipment, frequent tillage and lack 

of organic matter contribute to compaction 

problems for vegetable growers in the 

Northeast, where frequent rains often force 

growers into the fields when soils are wet. 

Compacted soils slow root development, 

hinder nutrient uptake, stunt plants, delay 

maturity and can worsen pest and disease 

problems. For example, the Cornell 

researchers found that slow-growing cabbages 

direct-seeded into compacted soils were 

vulnerable to flea beetle infestations. 

Yellow mustard’s deep tap root may 

make it a solid challenger to sudangrass as 

a compaction reliever. But it was sometimes 

difficult to establish in the test.“We still have 

a lot to learn about how best to grow these 

crops and how best to fit them into rotations 

with vegetables,”Wolfe says. 

Wolfe and his team assessed the cover crops’ 

effectiveness by measuring yields of subsequent 

crops and conducting a host of soil quality 

measurements, including infiltration rates, 

water-holding capacity, aggregate stability 

and organic matter levels.They will follow 

up this research by examining the effects of 

compaction on pathogenic and beneficial 

microorganisms in the soil. 

For more information, contact David Wolfe, 

(607) 255-5439, dww5@cornell.edu. 

the rotation will further build soil health and add 

nitrogen. Sorghum-sudangrass hybrids can provide 

needed soil structure benefits wherever 

intensive systems cause compaction and loss of 

soil organic matter reserves. See Summer Covers 

Relieve Compaction, above. 

Grown as a summer cover crop that is cut once 

and then suppressed or killed, sorghum-sudangrass 

can reduce weeds in fall-planted alfalfa. 

Sorghum-sudangrass suppressed alfalfa root 

growth significantly in a Virginia greenhouse 

study (109), but no effect was observed on alfalfa 

germination when alfalfa was no-till planted into 

killed or living sorghum-sudangrass (110). 

In California, some table grape growers use 

sorghum-sudangrass to add organic matter and to 

reduce the reflection of light and heat from the 

soil, reducing sunburn to the grapes. 


Sorghum-sudangrass hybrids can produce more 

organic matter per acre, and at a lower seed cost, 

than any major cover crop grown in the U.S. 


Incorporated sorghum-sudangrass residue 

reduces N availability to young crops more than 

oat residue but less than wheat residue (319). 

For suppressing root-knot nematodes in Idaho 

potato fields, rapeseed has proven slightly more 

effective and more dependable than sorghumsudangrass 

hybrids (322). 

SEED 

Cultivars. When comparing sorghum-sudangrass 

cultivars, consider traits such as biomass yield 

potential, tillering and regrowth ability, disease 

resistance, insect resistance (especially if greenbugs 

are a problem) and tolerance to iron deficiency 

chlorosis. 

If you plan to graze the cover crop, select 

sorghum-sudangrass hybrids and related crops 

with lower levels of dhurrin, the compound 

responsible for prussic acid poisoning. For 

maximum weed control, choose types high in 

sorgoleone, the root exudate that suppresses 

weeds. Sterile cultivars are best where escapes 

could be a problem, especially where crossing 

with johnsongrass (Sorghum halpense) is 

possible. 

To extend weed suppressive effects into the 

second season, select a cultivar known for weed 

suppression and leave roots undisturbed when 

the stalks are mowed or grazed (361). 


OVERVIEW OF LEGUME COVER CROPS 

Commonly used legume cover crops include: 

• Winter annuals, such as crimson clover, hairy 

vetch, field peas, subterranean clover and 

many others 

• Perennials like red clover, white clover and 

some medics 

• Biennials such as sweetclover 

• Summer annuals (in colder climates, the winter 

annuals are often grown in the summer) 

Legume cover crops often are used to: 

• Fix atmospheric nitrogen (N) for use by subsequent 

crops 

• Reduce or prevent erosion 

• Produce biomass and add organic matter to 

the soil 

• Attract beneficial insects 

Legumes vary widely in their ability to prevent 

erosion, suppress weeds and add organic matter 

to the soil. In general, legume cover crops do not 

scavenge N as well as grasses. Therefore, if you 

need a cover crop to take up excess nutrients 

after manure or fertilizer applications, a grass or a 

mixture is usually a better choice. 

Winter-annual legumes, while established in 

the fall,usually produce most of their biomass and 

N in spring.Winter-annual legumes must be planted 

earlier than cereal crops in order to survive the 

winter in many regions. Depending on your climate, 

spring management of legumes will often 

involve balancing early planting of the cash crop 

with waiting to allow more biomass and N production. 

Perennial or biennial legumes can fit many different 

niches, as described in greater detail in the 

individual sections for those cover crops. 

Sometimes grown for a short period between 

cash crops,these forage crops also can be used for 

more than one year and often are harvested for 

feed during this time. They can be established 

along with—or overseeded into—other crops 

such as wheat or oats, then be left to grow after 

cash crop harvest and used as a forage. Here 

they are functioning more as a rotation crop than 

a cover crop, but as such provide many benefits 

including erosion and weed control, organic matter 

and N production. They also can break 

weed, disease and insect cycles. 

Summer-annual use of legume crops includes, 

in colder climates, the use of the winter-annual 

crops listed above, as well as warm-season 

legumes such as cowpeas. Grown as summer 


annuals, these crops produce N and provide 

ground cover for weed and erosion control, as 

well as other benefits of growing cover crops. 

Establishment and management varies widely 

depending on climate, cropping system and the 

legume itself. These topics will be covered in the 

individual sections for each legume. 

Legumes are generally lower in carbon and 

higher in nitrogen than grasses. This lower C:N 

ratio results in faster breakdown of legume 

residues. Therefore, the N and other nutrients 

contained in legume residues are usually released 

faster than from grasses.Weed control by legume 

residues may not last as long as for an equivalent 

amount of grass residue. Legumes do not increase 

soil organic matter as much as grasses. 

Mixtures of legume and grass cover crops combine 

the benefits of both, including biomass production, 

N scavenging and additions to the 

system,as well as weed and erosion control.Some 

cover crop mixtures are described in the individual 

cover crop sections. 

GRASS/LEGUME MIXTURES EXPAND POSSIBILITIES 

Mixtures of two or more cover crops are 

often more effective than planting a 

single species.Cover crop mixtures offer 

the best of both worlds,combining the benefits of 

grasses and legumes,or using the different growth 

characteristics of several species to fit your needs. 

You can use cover crop mixtures to improve: 

• Winter survival 

• Ground cover 

• Use of solar energy 

• Biomass and N production 

• Weed control 

• Duration of active growing period 

• Range of beneficial insects attracted 

• Tolerance of adverse conditions 

• Forage options 

• Response to variable soil traits 

Possible disadvantages of cover crop mixtures 

may include: 

• Higher seed cost 

• Too much residue 

• More complicated management 

• Difficult to seed 

Crop mixtures can reduce risk in cropping systems 

because each crop in the mix may respond 

differently to soil, pest and weather conditions. In 

forage or grazing systems, for example, a mix of 

rye, wheat and barley is more nutritious, can be 

grazed over a longer period of time and is less 

likely to be devastated by a single disease. 

Using drought-tolerant plants in a perennial 

mix builds in persistence for dry years. Using a 

number of cover crops with “hard seed”that takes 

many months to germinate also improves coverage 

over a broader range of conditions. 

Mixing cultivars of a single species with varied 

maturity dates and growth habits maintains optimum 

benefits for a longer time. Orchardists in 

California mix subclovers to keep weeds at bay 

all season. One cultivar comes on early, then dies 

back as two later cultivars—one tall and one 

short—come on strong. Because they reseed 

themselves,the cooperative trio persists year after 

year. 

Sometimes you don’t know how much N may 

be left after cash crop harvest. Do you need a 

grass to scavenge leftover N, or a legume to provide 

fixed N A grass/legume cover crop mixture 

adjusts to the amount of available soil N: If there 

is a lot of N, the grass dominates; if there is not 

much available soil N, the legume will tend to 

dominate a mixture. In either case, you get the 

combined benefit of N scavenging by the grass 

cover crop and N additions from the legume 

cover crop. 

Mixing low-growing and taller crops, or faststarting 

grasses and slow-developing legumes, 

usually provides better erosion control because 

more of the ground is covered. The vegetation 

intercepts more raindrops before they can dis- 


lodge soil particles. Sunlight is used more efficiently 

because light that passes through the tall 

crop is captured by the low-growing crop. 

Adding grasses to a fall-seeded legume 

improves soil coverage over winter and increases 

the root mass to stabilize topsoil. A viny crop like 

vetch will climb a grass, so it can get more light 

and fix more N, or so it can be harvested more 

easily for seed. A faster-growing crop serves as a 

nurse crop for a slow-growing crop, while covering 

the ground quickly for erosion control. The 

possibilities are endless! 

Mixtures can complicate management, however. 

For example: 

• They may cost more to seed. Seeding rates for 

each component of the mix are usually lower 

than for sole-crop plantings, but the total seed 

cost may still be more. 

• The best time to kill one crop may not be the 

best for another crop, so a compromise date 

may be used. 

• If you use herbicides, your choices may be limited 

when you plant a mixture of legumes and 

nonlegumes. 

• Sometimes you can end up with more residue 

than your equipment can handle. 

The benefits of a mixture will usually outweigh 

these disadvantages,but you need to be prepared to 

manage the mixture carefully to prevent problems. 

Each cover crop chapter gives examples of specific 

mixtures that have been tested and work well. 

Try some of the proven cover crop mixtures, and 

create your own tailor-made mixtures. Remember 

that adding another crop increases the diversity on 

your farm, and is likely to increase the many proven 

benefits of rotations over monocropping. 

BERSEEM CLOVER 

Trifolium alexandrinum 

Also called: Egyptian clover 

Type: summer annual or winter 

annual legume 

Roles: suppress weeds, prevent 

erosion, green manure, chopped 

forage, grazing 

Mix with: oats, ryegrass, small 

grains as nurse crops; as nurse crop 

for alfalfa 

See charts, p. 47 to 53, for ranking 


summer annual 

winter annual 

Afast-growing summer annual, berseem 

clover can produce up to 8 tons of forage 

under irrigation. It’s a heavy N producer 

and the least winter hardy of all true annual 

clovers.This makes it an ideal winterkilled cover 

before corn or other nitrogen-demanding crops in 

Corn Belt rotations. Berseem clover draws down 

soil N early in its cycle. Once soil reserves are 

used up, it can fix 100 to 200 lb. N/A or more. It 

establishes well with an oat nurse crop, making it 

an excellent cover for small grain>corn>soybean 

rotations in the Midwest. 

BERSEEM CLOVER 87

In Iowa, the cultivar BIGBEE compares favorably 

with alfalfa in its regrowth following small grain 

harvest,its feed value and its tolerance to drought 

and excess moisture (119). As a winter annual in 

California, irrigation usually is needed to allow 

berseem to achieve its full potential. Its peak 

growth period during the West Coast’s rainy season 

and its highly efficient water use compare 

favorably to alfalfa as a high-producing forage and 

green manure. Alfalfa has its peak growth during 

dry summer periods (127). 

BENEFITS 

Green manure. Berseem clover is the fertility 

foundation of agriculture in the Nile Delta, and 

has nourished soils in the Mediterranean region 

for millennia. MULTICUT berseem clover averaged 

280 lb. N/A in a six-year trial in California with 

six cuttings per year (127), and grew faster than 

BIGBEE in one Iowa report (118). Berseem is less 

prone to possible N leaching if grown to maturity 

without cutting, when it produces 100 to 125 

lb. N/A. Top N fixation occurs when soils have 

less than 150 lb. N/A (127). A single cutting can 

yield 50 to 100 lb. topgrowth N/A. Berseem’s 

dry matter N concentration is about 2.5 percent 

(127). 

Biomass. Berseem clover produced the most 

biomass (6,550 lb./A) of five winter annual 

legumes in a two-year Louisiana test,and came in 

second to arrowleaf clover (Trifolium vesiculosum) 

in N, accumulating 190 lb. N/A to 

arrowleaf’s 203 lb. N/A. Also tested were TIBBEE 

crimson clover WOOGENELLUP subterraneum 

clover and WOODFORD bigflower 

vetch. All but arrowleaf clover 

were able to set seed by May 13 

and regrow in the fall,despite the 

herbicides used to suppress 

them in spring and to control 

weeds during summer (23). 

In recent Alberta legume trials, 

berseem clover averaged 3,750 lb. dry matter/A 

over three years at a site where hairy vetch and 

field peas produced 5,300 lb. and 4,160 lb., 

MULTICUT berseem 

clover averaged 280 

lb. N/A in a six-year 

California trial. 

respectively. With irrigation, berseem clover 

topped 19 other legumes at the same site with a 

mean yield of 5,500 lb. DM/A. 

Smother crop. Planted with oats or annual 

ryegrass, berseem clover suppresses weeds well 

during establishment and regrowth after oat 

harvest. 

Companion crop. Planted with oat, the two 

crops can be harvested together as silage, haylage 

or hay, depending on the crop’s development 

stage. Berseem/oat haylage has very high feed 

quality if cut at oats’boot stage (120).Dry seasons 

favor development of an oat grain crop, after 

which berseem clover can be cut one, two or 

three times in the Midwest. 

Quick growing. At 60 F, berseem clover will 

be ready to cut about 60 days after planting. 

Legume nurse crop. Because of its quick 

germination (seven days), quick growth and 

winterkilling tendency, berseem clover can be 

used as a nurse crop for alfalfa. 

Seed crop. Berseem produces up to 1,000 lb. 

seed/A if it is left to mature. Only BIGBEE berseem 

clover has hard seed that allows natural selfreseeding, 

and it reseeds too late for timely planting 

of most summer crops (77). 

Grazing and forage crop. At 18 to 28 percent 

protein, young berseem clover is comparable to 

or better than crimson clover or alfalfa as feed. 

No cases of bloat from grazing berseem clover 

have been reported (121, 225). 

Forage quality remains acceptable 

until the onset of seed production. 

BIGBEE berseem clover 

and TIBBEE crimson produce 

more fall and winter growth than 

do other winter annual clovers in 

the South. BIGBEE continues producing 

longer into the spring than other 

legumes, extending cuttings into late May or 

early June in Mississippi (179). 


Crimson-Berseem Clover Combo Works as Corn Underseeding 

DEXTER, MI.—Mixing berseem clover 50:50 boxes for a good seed flow with very little 

with crimson clover for an interseeded legume seed damage. 

cover in corn works well for Dexter, Mich., 

“The berseem clover keeps growing as the 

farmer Paul Guenther. “They seem to thrive on corn grows, and can get up to knee high,” says 

opposite conditions, and both survive most of Guenther. “The crimson doesn’t get much 

the time,” he says. He plants 8 to 10 lb. mixed taller after the corn canopy closes, but the 

seed/A in a 12- to 15-inch band between the leaves seem to get bigger.”The berseem clover 

rows at final cultivation. 

winterkills, and the crimson comes back in 

Guenther applies the seed through 

spring. He plans to seed the mixture in the 

insecticide boxes from a corn planter.They’re middles between his ridge-tilled corn rows, 

mounted on a toolbar that’s part of an old then kill the crimson with wide sweeps at first 

anhydrous rig he uses to apply 28 percent N. cultivation the following spring. 

Typically, the feed cups that handle granular He’s likes how the mix performs much 

insecticide run too fast for small seeds and better than the interseeded annual medic he 

grind them up. He overcame that problem by tried for several years.“They just don’t tolerate 

gearing down the rotation with a jack shaft the shade” under corn or bean rows, but he 

that allows the rig to travel 65 feet for every lauds how the annual medics work in the fullseason 

sunshine of the family’s market garden 

revolution of the metering device. That 

allows him to open the feed gates of the between tomatoes or beet rows (134). 

MANAGEMENT 

Establishment 

Berseem prefers slightly alkaline loam and silty 

soils but grows in all soil types except sands. Soil 

phosphorus can limit berseem clover growth. 

Fertilize with 60 to 100 lb. P2O5/A if soil tests 

below 20 ppm (127). Boron also may limit 

growth, so test soil to maintain levels (225). 

Berseem tolerates saline conditions better than 

alfalfa and red clover (91). Use R-type inoculant 

suitable for berseem clover and crimson clovers. 

Broadcast or drill berseem seed alone or with 

spring grains onto a firm, well-prepared seedbed 

or closely cropped sod so that it is 1 /4-inch deep 

with a light soil covering. To improve seed-soil 

contact and to maintain seed-zone moisture, 

cultipack or roll soil before and after broadcast 

seeding (127). Dry, loose soil will suppress 

germination. 

Recommended seeding rates are 8 to 12 lb./A 

drilled or 15 to 20 lb./A broadcast.Excessive rates 

will create an overly thick stand that prevents 

tillering and spreading of the root crowns. 

Montana trials set the optimum seeding rate at 

about 8 lb./A drilled in 12-inch rows, with a higher 

rate in narrower rows where herbicides are not 

used to control weeds (364). 

Midwest. Seed after April 15 to avoid crop loss 

due to a late frost.Berseem frostseeded at 15 lb./A 

yields well in the upper Midwest. In southern 

Michigan, frostseeded berseem clover produced 

1.5 T dry matter/A and 85 lb. N/A (308), but frost 

risk is significant (124). 

Iowa tests over four years showed that interseeded 

berseem and oats averaged 76 percent 

more dry matter (ranging from 19 to 150 percent) 

than oats alone.Underseeding berseem clover did 

not significantly reduce oat yields in another Iowa 

study. Seed early- to mid-April in Iowa (122). 

When seeding a mixture, harvest goals affect 

variety selection and seeding rates,Iowa researchers 

have found. If establishment of an optimum 

berseem clover stand for green manure is most 

important, oat or other small grain crop seeded at 

about 1 bushel per acre will protect the young 

clover and help to break the soil crust. If early 

BERSEEM CLOVER 89

Southeast. Fall planting in mild regions provides 

effective weed control as well as N and organic 

matter for a spring crop. Seed Aug. 25 to Oct. 15 

in Mississippi or up to Dec.1 in Florida.For a coolseason 

grass mixture, plant 12 lb. berseem clover 

seed with 10 lb. orchardgrass or 20 lb. annual or 

perennial ryegrass/A (179). 

West. Berseem does best in California’s Central 

Valley when planted by the first or second week 

of October. If planting is delayed until November, 

seedlings will start more slowly in the cool of 

winter (127). 


BERSEEM CLOVER (Trifolium alexandrinum) 

forage before green manuring is the goal, seed a 

mixture of 4 bu.oats and 15 lb.berseem/A.If biomass 

quantity is foremost, use a short-stalked, 

long-season oat. If oat grain production is 

primary, keep oat seeding rate the same, but 

select a short-season, tall variety to reduce the 

likelihood of berseem clover interfering with 

grain harvest (119). 

Berseem clover also can be a late-summer crop. 

Planted in mid-August in the Corn Belt, it should 

grow about 15 inches before frost,provide winter 

erosion protection and break down quickly in 

spring to deliver N from its topgrowth and roots. 

You can overseed berseem clover into standing 

small-grain crops, a method that has worked well 

in a series of on-farm tests in Iowa (118).Plant the 

berseem as late as three weeks after the grain 

crop germinates or after the tillering stage of winter-seeded 

small grains. Use a heavy seeding rate 

to compensate for reduced seed-soil contact. 

Frostseeding in late winter into winter wheat has 

not worked in several attempts in Pennsylvania 

(302) and Iowa (124). 


Mowing for green manure. Clip whenever 

plants are 12 to 15 inches tall and basal shoots 

begin to grow. This will be 30 to 60 days after 

planting, depending on weather, field and moisture 

conditions.Mow again every 25 to 30 days to 

encourage growth of up to 4 T/A. Keep stubble 

height at least 3 to 4 inches tall, because plants 

regrow from lower stem branches. 

To maximize dry matter production, cut as 

soon as basal bud regrowth reaches 2 inches 

(127). At the latest, clip before early flowering 

stage or plants will not regrow. Berseem 

clover responds best when field traffic is 

minimized (119). 

Mowed berseem clover left in the field as green 

manure can hinder regrowth of the legume from 

its lower stems. To lessen this problem, flail or 

sickle-bar mow then rake or fluff with a tedder at 

intervals until regrowth commences (124). 

Remember that berseem clover has a tap root 

and shallow 6- to 8-inch feeder root system (119). 

In thin plantings or well-drained soils, it can be 

susceptible to drought, a trait that could trigger 

mowing, grazing or killing earlier than originally 

planned (143). 

Abundant soil N will restrict N fixation by 

berseem clover, but moderate amounts up to 150 

lb. N/A did not limit annual fixation in north central 

California. Researchers explain that berseem 

clover draws heavily on soil N during early 

growth. When soil N was depleted in this test, 

berseem began fixing N rapidly until it produced 

seed and died (368). 

Berseem made its N contribution to soil in the 

final third of its cutting cycle—regardless of initial 

soil N availability—in all six years of the study. 

Nitrogen fixation was closely correlated to a drop 


in water-use efficiency in the trial. After producing 

from 400 to 640 lb. of dry matter per acre-inch of 

water in the first four cuttings,production dropped 

to 300 lb. DM/A-in. for the final two cuttings (368). 

Small grain companion. Underseeded berseem 

clover provided about 1.2 T forage dry matter/A 

after oat harvest in Iowa, worth about $75/A as 

commercial livestock feed. Removing the forage 

decreases the soil-saving ground cover and N contribution 

(122), trading soil and 

N benefits for attractive nearterm 

income. 

In the Midwest, greenchop 

an oat/berseem clover mixture 

when oat is at the pre-boot 

stage to avoid berseem clover 

going to seed early and, therefore, 

not producing maximum 

nitrogen. Oats have high forage 

N values at this stage. Monitor 

carefully during warm periods to avoid nitrogen toxicity 

(299). 

A Montana study found that spring plantings of 

berseem clover will produce the most legume dry 

matter and N if clear seeded.If,however,you wish to 

maximize total dry matter and protein, seeding with 

oats is recommended. The oat nurse crop suppressed 

weeds well and increased total dry matter production 

by 50 to 100 percent regardless of whether plots 

were cut two,three or four times (356). 

Killing 

Berseem dies when exposed to temperatures below 

20 F for several days, making winterkill a virtual 

certainty in Zone 7 and colder. This eliminates 

the need for herbicides or mechanical killing after 

a cold winter, and hastens delivery of nutrients to 

the soil. 

To kill berseem clover ahead of fall-planted 

crops,wait for it to die after blooming,use multiple 

diskings or apply herbicides.In mild areas,berseem 

clover grows vigorously through late spring. BIGBEE 

berseem clover remained vegetative until early May 

or later in an experiment at a northern Mississippi 

(Zone 7) site. Until it reaches full bloom, it will 

require either tillage or a combination of herbicides 

and mechanical controls to kill it. 

The least winter hardy of 

the true annual clovers, 

berseem can be planted 

with oats in the Corn Belt 

and produce abundant N 

before winterkilling. 

In a northern Mississippi mechanical control 

study, BIGBEE berseem clover added the most dry 

matter after mid-April compared to hairy vetch, 

MT. BARKER subterranean clover and TIBBEE crimson 

clover. Berseem and hairy vetch remained 

vegetative until mid-May, but by early May, berseem 

clover and crimson had a considerable 

amount of stems laying down (79). 

Rolling with 4-inch rollers killed less berseem 

clover than hairy vetch or crimson when the 

legumes had more than 10 

inches of stem laying on the 

ground. Kill rate was more 

than 80 percent for the latter 

two crops, but only 53 percent 

for berseem clover. 

Without an application of 

atrazine two weeks prior to 

either flail mowing or rolling 

with coulters,the mechanical 

controls failed to kill more 

than 64 percent of the berseem clover until early 

May, when flailing achieved 93-percent control. 

Atrazine alone reduced the stand by 68 percent in 

early April,72 percent in mid-April and 88 percent 

in early May (79). 


Avoid direct seeding small-seeded vegetables into 

fields where you have incorporated berseem 

clover within the past month. Berseem clover, 

crimson clover and hairy vetch residue incorporated 

directly into the seed zone may suppress germination 

and seedling development of onion, carrot 

and tomato, based on interaction of extracts from 

these legumes and the seeds in lab tests (26). 

Lygus bugs have been a serious problem in 

California seed production, and virus outbreaks 

can cause serious damage during wet springs 

where berseem grows as a winter annual.Where 

virus is a concern, use JOE BURTON, a resistant 

cultivar. BIGBEE is susceptible to crown rot and 

other root diseases common to forage legume 

species (127). 

Berseem, like other clovers, shows little resistance 

to root-knot nematode (Meloidogyne 

spp.). It seems to be particularly favored by 

rabbits (302). 

BERSEEM CLOVER 91

Nodulation: Match Inoculant to Maximize N 

With the help of nitrogen-fixing bacteria, 

legume cover crops can supply some or all 

of the N needed by succeeding crops. This 

nitrogen-producing team can’t do the job right 

unless you carefully match the correct 

bacterial inoculant with your legume cover 

crop species. 

Like other plants, legumes need nitrogen to 

grow. They can take it from the soil if enough 

is present in forms they can use. Legume roots 

also seek out specific strains of soil-dwelling 

bacteria that can “fix” nitrogen gas from the air 

for use by the plant.While many kinds of 

bacteria compete for space on legume roots, 

the root tissues will only begin this symbiotic 

N-fixing process when they encounter a 

specific species of rhizobium bacteria. Only 

particular strains of rhizobia provide optimum 

N production for each group of legumes. 

When the root hairs find an acceptable 

bacterial match, they encircle the bacteria to 

create a nodule. These variously shaped lumps 

on the root surfaces range in size from a BB 

pellet to a kernel of corn. Their pinkish 

interiors are the visible sign that nitrogen 

fixation is at work. 

Nitrogen gas (N2) from air in the spaces 

between soil particles enters the nodule.The 

bacteria contribute an enzyme that helps 

convert the gas to ammonia (NH3).The plant 

uses this form of N to make amino acids, the 

building blocks for proteins. In return, the host 

legume supplies the bacteria with 

carbohydrates to fuel the N-fixation process. 

The rate of N fixation is determined largely 

by the genetic potential of the legume species 

and by the amount of plant-available N in the 

soil. Other environmental factors such as heat 

and moisture play a big role, as well. Fueling N 

fixation is an expensive proposition for the 

legume host, which may contribute up to 20 

percent of its carbohydrate production to the 

root-dwelling bacteria. If the legume can take 

up free N from the soil, it won’t put as much 

energy into producing nodules and feeding 

bacteria to fix nitrogen from the air. 

Perennial legumes fix N during any time of 

active growth. In annual legumes, N fixation 

peaks at flowering.With seed formation, it 

ceases and the nodules slough from the roots. 

Rhizobia return to the soil environment to 

await their next encounter with legume roots. 

These bacteria remain viable in the soil for 

three to five years, but often at too low a level 

to provide optimum N-fixation when legumes 

return to the field. 

If legume roots don’t encounter their ideal 

bacterial match, they work with the best strains 

they can find. They just don’t work as 

efficiently together and they produce less N. 

Inoculating seeds with the correct strain before 

planting is inexpensive insurance to make sure 

legumes perform up to their genetic potential. 

Clover inoculum, for example, costs just 6 cents 

per pound of seed treated, plus about 12 cents 

per pound for an enhanced sticker that buffers 

and feeds the seedling (194). 

While they are alive, legumes release little 

or no nitrogen to the soil. The N in their roots, 

stalks, leaves and seeds becomes available 

when the plants die naturally or are killed 

by tillage, mowing or herbicide. This plant 

material becomes food for microbes, worms, 

insects and other decomposers. 

Crop Systems 

Flexible oats booster. In the Corn Belt,berseem 

clover seeded with can helps diversify corn>soybean 

rotations,breaking pest cycles and providing 

some combination of grain and/or forage harvest, 

erosion control and N to the following corn crop. 

An added benefit is that it requires no tillage or 

herbicide to kill it in spring (122). Plant 4 bu. oats 

with 12 lb. berseem/A. 

In a four-year Iowa study, planting berseem 

clover with oats increased net profit by $39/A 

compared with oats alone.The clover was baled 


Microorganisms mineralize, or convert, the 

complex “organic” forms of nitrogen in the 

plant material into inorganic ammonium 

and nitrate forms, once again making the 

N available to plants. How quickly the 

mineralization of N occurs is determined by 

a host of environmental and chemical factors. 

These will affect how much of that legume 

N is available to the next crop or has the 

potential to leach from the soil. 

For more information about mineralization 

and how much you can reduce your N 

fertilizer rate for crops following legumes, 

see How Much N (p. 22). 

To get the most from your legume/bacteria 

combination: 

• Choose appropriate legume species for 

your climate, soils and cropping system. 

Also, consider the amount of N it can 

deliver when you will need it. 

• Match inoculant to the species of legume 

you are growing. See Chart 3B, Planting 

(p. 51) to determine the best inoculant to 

use. 

• Coat seed with the inoculant just before 

planting. Use milk, weak sugar water or a 

commercial sticking agent to help the 

material stick to the seeds. Use only fresh 

inoculant (check the package’s expiration 

date), and do not expose packages or 

inoculated seed to excessive heat or direct 

sunlight. 

Mix the sticker with non-chlorinated water 

and add the inoculant to create a slurry, then 

thoroughly coat seeds. Seed should be dry 

enough to plant within half an hour. 

Re-inoculate if you don’t plant the seed within 

48 hours. Mix small quantities in a five-gallon 

bucket or tub, either by hand or using a drill 

equipped with a paint-mixer attachment. For 

larger quantities, use special inoculant mixing 

hoppers or a cement mixer without baffles. 

On-farm use of commercial sticker/inoculant 

products has produced more consistent results 

than pelleting methods applied by seed 

companies (357). Gum arabic stickers with 

sugars and liming agents boost the chances 

for optimum nodulation over water-applied 

inoculant alone. Pre-inoculated (“rhizo-coated”) 

seed weighs about one-third more than raw 

seed, so increase seeding rates accordingly. 

Commercial sticker/inoculant products add 

about 5 percent to seed weight. 

Check nodulation as the plants approach 

bloom stage. Push a spade in the soil about 6 

inches below the plant. Carefully lift the plant 

and soil, gently exposing roots and nodules. 

(Yanking roots from the soil usually strips off 

nodules).Wash gently in a bucket of water to 

see the extent of nodulation. Slice open nodules. 

A pink or reddish interior indicates active N- 

fixation. Remember, an overabundance of soil 

nitrogen from fertilizer, manure or compost 

can reduce nodulation. 

For more information about nodulation, 

see two books by Marianne Sarrantonio: 

Northeast Cover Crop Handbook (1994, 

Rodale Institute, Kutztown, Pa. 19530) 

pp. 35-49, and Methodologies for Screening 

Soil-Improving Legumes (1991, Rodale 

Institute Research Center) pp. 63-67. 

for forage and the underseeded oats were harvested 

for grain. Not calculated in the benefit 

were the 40 to 60 lb. N/A provided to the following 

corn or other soil-improvement benefits.The 

oats/berseem mix produced 70 percent more biomass,increased 

subsequent corn yields by 10 percent 

and reduced weed competition compared 

with a year of oats alone (122). 

Pure berseem clover regrowth averaged 1.2 T 

dry matter/A,which can be used as forage or green 

manure. These options could help oats become an 

economically viable crop for Midwest crop/live- 

BERSEEM CLOVER 93

stock farms in an era of decreasing government 

payments for corn and soybeans (122, 123). 

Wheat companion. Berseem was one of six 

legume intercrops that improved productivity 

and profit of wheat and barley crops in low-N 

soils under irrigated conditions in northwestern 

Mexico. All of the legumes (including common 

and hairy vetch, crimson clover, New Zealand and 

Ladino white clover, and fava beans) provided 

multiple benefits without decreasing grain yield 

of 15 to 60 bu./A on the heavy clay soil. 

Wheat and legumes were planted at normal 

monoculture rates with wheat in double rows 

about 8 inches apart atop 30-inch beds, and 

legumes in the furrows. In a second, related 

experiment, researchers found they could more 

than double total wheat productivity (grain and 

total dry matter) by interplanting 24-inch strips of 

berseem clover or hairy vetch with double rows 

of wheat 8 inches apart. Control plots showed 

wheat planted at a greater density did not 

increase yield (290). 

Vegetable overseeding. Berseem can be overseeded 

into spring vegetables in northern 

climates where it thrives at moderate temperatures 

and moisture. Berseem is 

well suited to a “mow and 

blow” system where strips of 

green manure are chopped and 

transferred to adjacent crop 

strips as a green manure and 

mulch (302). 

Boost the N plow-down 

potential of old pastures or 

winter-killed alfalfa by no-tilling 

or interseeding berseem clover. Or, broadcast 

seed then incorporate with light harrowing. 


• Bee-friendy because its white or ivory blossoms 

have no tripping mechanism. 

• Because of its short roots, berseem clover does 

not utilize phosphorus to the depth that 

mature, perennial alfalfa does. 

• Winterkilled berseem allows for earlier spring 

planting than winter-hardy annuals. As a dead 

organic mulch, it poses no moisture depletion 

risk, but may slow soil warming and drying 

compared to erosion-prone bare fallow. 

SEED 

Mow strips of berseem 

between vegetable rows 

and blow the clippings 

around the plants for 

mulch. 

Cultivars. BIGBEE berseem clover was selected 

from other traditional cultivars for its cold-tolerance, 

which is similar to crimson clover. Some of 

the strong winter production tendency found in 

non-winter hardy berseem clover was sacrificed 

to obtain BIGBEE’S winter hardiness (127). Mature 

BIGBEE plants hold their seeds well and produce 

adequate hard seed for reseeding. Other berseem 

clover cultivars have less hard seed and will not 

dependably reseed (225). 

California tests show MULTICUT berseem clover 

produces 20 to 25 percent more dry matter than 

BIGBEE. It has greater N-fixing ability, blooms later, 

and has a longer growing period than other 

varieties, but is not as cold 

tolerant as BIGBEE (127). 

In California, BIGBEE begins 

to flower in mid-May, about 

two weeks ahead of MULTICUT. 

MULTICUT grows faster and produces 

more dry matter in California 

conditions, averaging 

about 1.6 T/A more in a six-year 

study. When the five or six 

cuttings per year were clipped and removed, 

MULTICUT was about 6 inches taller at each clipping 

than other varieties (368). In Montana tests, BIGBEE 

out-yielded MULTICUT in eight of 13 locations (314). 

Berseem clover is: 

• Similar to alfalfa in drought tolerance, but 

some cultivars can tolerate more soil moisture 

than alfalfa or sweet clover 

• Similar in seed size to crimson clover 

Seed sources. Albert Lea, Cal/West, Harmony, 

L.L. Olds, Peaceful Valley, Pennington, Rupp, 

Sexauer, Welter and Wolf River. (Cal/West and 

Welter have MULTICUT). See Seed Suppliers 

(p. 166). 


COWPEAS 

Vigna unguiculata 

Also called: southern peas, 

blackeye peas, crowder peas 

Type: summer annual legume 

Roles: suppress weeds, N source, 

build soil, prevent erosion, forage 

Mix with: sorghum-sudangrass 

hybrid or foxtail hay-type millet 

for mulch or plow-down before 

vegetables; interseeded with corn 

or sorghum 



summer annual 

minimal irrigation-establishment only 

Cowpeas are the most productive heatadapted 

legume used agronomically in the 

U.S. (221). They thrive in hot, moist zones 

where corn flourishes, but require more heat for 

optimum growth (211). Cowpea varieties have diverse 

growth habits. Some are short, upright bush 

types.Taller, viny types are more vigorous and better 

suited for use as cover crops. Cowpeas protect 

soil from erosion,smother weeds and produce 100 

to 150 lb.N/A.Dense residue helps to improve soil 

texture but breaks down fairly quickly. Excellent 

drought resistance combined with good tolerance 

of heat, low fertility and a range of soils make cowpeas 

viable throughout the temperate U.S. where 

summers are warm or hot but frequently dry. 

Cowpeas make an excellent N source ahead of 

fall-planted crops and attract many beneficial 

insects that prey on pests. Used in California in 

vegetable systems and sometimes in tree crops, 

cowpeas also can be used on poor land as part of 

a soil-building cover crop sequence. 

BENEFITS 

Weed-smothering biomass. Drilled or broadcast 

cowpea plantings quickly shade the soil to 

block out weeds.Thick stands that grow well can 

out-compete bermudagrass where it does not produce 

seed and has been plowed down before 

cowpea planting (211). TROY cowpeas produced 

an average of about 5,100 lb. dry matter/A in a 

two-year Nebraska screening of cover crops. 

Soybeans averaged about 7,800 lb. DM/A in 

comparison plots (271).Typical biomass production 

is 3,000 to 4,000 lb./A (302). 

Quick green manure. Cowpeas nodulate 

profusely, producing an average of about 130 lb. 

N/A in the East, and 200 lb. N/A in California. 

Properly inoculated in nitrogen deficient soils, 

cowpeas can produce more than 300 lb.N/A (91). 

Plowdown often comes 60 to 90 days after planting 

in California (221). Higher moisture and more 

soil N favor vegetative growth rather than seed 

production. Unlike many other grain legumes, 

cowpeas can leave a net gain of nitrogen in the 

field even if seed is harvested (302). 

IPM insectary crop. Cowpeas have “extrafloral 

nectaries”—nectar-release sites on petioles and 

leaflets—that attract beneficial insects, including 

many types of wasps,honeybees,lady beetles,ants 

COWPEAS 95

and soft-winged flower beetles (351). Plants have 

long, slender round pods often borne on bare 

petioles above the leaf canopy. 

Intercropping cotton with cowpeas in India 

increased levels of predatory ladybugs and parasitism 

of bollworms by beneficial wasps. Intercropping 

with soybeans also increased parasitism 

of the bollworms compared with plots intercropped 

with onions or cotton without an intercrop. 

No effects on overall aphid, leafhopper or 

bollworm populations were observed (351). 

Companion crop. Thanks to its moderate shade 

tolerance and attractiveness to beneficial insects, 

cowpeas find a place in summer cover crop mixtures 

in orchards and vineyards in the more temperate 

areas of California. Avoid use under a heavy 

tree canopy,however,as cowpeas are susceptible to 

mildew if heavily shaded (211). As in much of the 

tropical world where cowpeas are a popular food 

crop,they can be underseeded into corn for late-season 

weed suppression and post-harvest soil coverage 

(302). 

Seed and feed options. Cowpea seed (yield 

range 350 to 2,700 lb./A) is valued as a nutritional 

supplement to cereals because of complementary 

protein types.Seed matures in 90 to 240 days. 

Cowpeas make hay or forage of highest feed value 

when pods are fully formed and the first have 

ripened (91). A regular sickle-bar mower works 

for the more upright-growing cultivars (91, 351). 

Crimping speeds drying of the rather fleshy stems 

to avoid over-drying of leaves 

before baling. 

Low moisture need. Once 

they have enough soil moisture 

to become established, cowpeas 

are a rugged survivor of 

drought. Cowpeas’ delayed leaf 

senescence allows them to survive and recover 

from midseason dry spells (15). Plants can send 

taproots down nearly 8 feet in eight weeks to 

reach moisture deep in the soil profile (81). 

Cultivars for diverse niches. Cover crop cultivars 

include CHINESE RED,CALHOUN and RED RIPPER, 

all viny cultivars noted for superior resistance to 

rodent damage (258). IRON AND CLAY, a mixture of 

two formerly separate cultivars widely used in the 

Southeast, combines semi-bushy and viny plants 

and resistance to rootknot nematodes and wilt. 

Most of the 50-plus commercial cowpea cultivars 

are horticultural. These include “crowder 

peas” (seeds are crowded into pods), grown 

throughout the temperate Southeast for fresh processing,and 

“blackeye peas,”grown for dry seed in 

California. 

Use leafy,prostrate cultivars for the best erosion 

prevention in a solid planting. Cultivars vary significantly 

in response to environmental conditions. 

Enormous genetic diversity in more than 

7,000 cultivars (91) throughout West Africa,South 

America and Asia suggests that breeding for forage 

production would result in improved cultivars 

(15, 351) and cover crop performance. 

Easy to establish. Cowpeas germinate quickly 

and young plants are robust, but they have more 

difficulty emerging from crusted soils than 

soybeans. 

MANAGEMENT 

Cowpeas thrive under 

hot, moist conditions, 

but also tolerate drought 

and low soil fertility. 

Establishment 

Don’t plant cowpeas until soil temperature is a 

consistent 65 F and soil moisture is adequate for 

germination—the same conditions soybeans 

need. Seed will rot in cool, wet soils (81). 

Cowpeas for green manure can be sown later in 

summer (302), until about nine 

weeks before frost. Cowpeas 

grow in a range of well-drained 

soils from highly acid to neutral,but 

are less well adapted to 

alkaline soils. They will not 

survive in waterlogged soils 

or flooded conditions (91). 

In a moist seedbed, drill cowpeas 1 to 2 inches 

deep at about 30 to 90 lb./A,using the higher rate 

in drier or cooler areas or for larger-seeded cultivars 

(302, 351). While 6- to 7-inch row spacings 

are best for rapid groundcover or a short growing 

season,viny types can be planted in 15- to 30-inch 

rows. Pay particular attention to pre-plant weed 


control if you go with rows, using pre-cultivation 

or 2,4-D and MCPA. 

If you broadcast seed,increase the rate to about 

100 lb./A and till lightly to cover seed. A lower 

rate of 70 lb./A can work with good moisture and 

effective incorporation (302). Broadcast seeding 

usually isn’t as effective as drilling, due to cowpeas’ 

large seed size. You can plant cowpeas 

after harvesting small grain, usually with a single 

disking if weed pressure is low. No-till planting is 

also an option. Use special “cowpea” inoculant 

which also is used for sunn hemp (Crotolaria 

juncea),another warm-season annual legume.See 

Up-and-Coming Cover Crops (p. 158). 


Cowpea plants are sometimes mowed or rolled to 

suppress regrowth before being incorporated for 

green manure. It’s best to incorporate cowpeas 

while the entire crop is still green (302) for quickest 

release of plant nutrients.Pods turn cream or brown 

upon maturity and become quite brittle. Stems 

become more woody and leaves eventually drop. 

Crop duration and yield are markedly affected 

by night and day temperatures as well as day 

length. Dry matter production peaks at temperatures 

of 81 F day and 72 F night (91). 

Killing 

Mowing at any point stops vegetative development, 

but may not kill plants without shallow 

tillage. Recent tests show mowing and rolling 

alone do not consistently kill cowpeas (69). Herbicides 

that control cowpeas include glyphosate, 

paraquat, 2,4-D and dicamba (25). 


Farmers using cowpeas as cover crops do not 

report problems with insects that are pests in 

commercial cowpea production, such as Lygus 

bugs and 11-spotted cucumber beetle (69, 256, 

63). Insect damage to cowpea cover crops is 

most likely to occur at the seedling stage. 

Once cowpea plants form pods, they may 

attract stinkbugs,a serious economic pest in parts 

of the lower Southeast. However, no significant 

stinkbug presence was reported in three years of 

COWPEAS (Vigna unguiculata) 

screening in North Carolina. If stinkbugs are a 

concern, remember these points: 

• Flail mowing or incorporating cowpeas at 

pod set will prevent a stinkbug invasion. By that 

time, cowpeas can provide good weed suppression 

and about 90 percent of their nitrogen contribution 

(256). However, waiting too long before 

mowing or incorporation will flush stinkbugs 

into adjacent crops. Leaving remnant strips of 

cowpeas to attract stinkbugs may reduce movement 

into other crops, as long as the cowpeas 

keep producing enough new pods until the cash 

crop is no longer threatened. 

• Plan crop rotations so the preceding,adjacent 

and succeeding crops are not vulnerable or are 

resistant to stinkbugs. 

• If you plan to use an insecticide to control 

another pest, the application may also help manage 

stinkbugs (263). 

No cowpea cultivar is resistant to root rot, but 

there is some resistance to stem rot. Persistent 

wet weather before development of the first true 

leaf and crowding of seedlings due to poor seed 

spacing may increase damping off. To reduce 

disease and nematode risks, rotate with four or 

five years of crops that aren’t hosts. Also plant 

seed into warm soils and use certified seed of 

tolerant varieties (81). IRON and other nematodetolerant 

cowpea cultivars reduced soybean cyst 


COWPEAS 97

Cowpeas Provide Elegant Solution to Awkward Niche 

PARTRIDGE, Kan.—Cowpeas fill a rotational decomposition. He runs an S-tine field cultivator 

1 to 2 inches deep just before planting 

rough spot between milo (grain sorghum) and 

wheat for Jim French, who farms about 640 wheat to set back fall weeds, targeting a 20 

acres near Partridge, Kan. 

to 25 percent residue cover. The cowpeas 

“I miss almost a full season after we take improve rainfall infiltration and the overall 

off the milo in late October or November until ability of the soil to hold moisture. 

we plant wheat the following October,” says French observes that the timing of rainfall 

French.“Some people use cash crops such as after cowpea planting largely determines the 

oats or soybeans. But with cowpeas, I get wind weediness of the cover crop.“If I get a week 

erosion control, add organic matter to improve to 10 days of dry weather after I plant into 

soil tilth, save on fertilizer and suppress weeds moisture, the cowpeas will out-compete the 

for the wheat crop. Plus I have the options of weeds. But if I get rain a few days after 

haying or grazing.” 

planting, they’ll be weedy.” 

He chisel plows the milo stubble in late 

French manages his legumes to stay in 

April, disks in May and field cultivates just compliance with new USDA farm program 

before planting about the first week of 

provisions.The Freedom to Farm Act allows 

June. He drills 30 to 40 lb./A of CHINESE RED vegetables used as green manure, haying or 

cowpeas 1 to 2 inches deep when soil 

grazing to be planted on program acres, but 

temperature reaches 70 F. Growth is rapid, prohibits planting vegetables for seed harvest 

and by early August he kills the cowpeas by on those acres. The rules list cowpeas as a 

making hay, having his cattle graze them off vegetable, even though different cultivars are 

or by incorporating them for maximum soil used for culinary production. Use of grain 

benefit. 

legumes such as lentils, mung beans and dry 

French says cowpeas usually produce 

peas (including Austrian winter peas) is not 

about 90 to 120 lb. N/A—relatively modest for restricted by the act, opening flexible rotation 

a legume cover—but he feels his soil greatly options. 

benefits from the residue, which measured 

French is working with Rhonda Janke of 

8,000 lb./A in one of his better fields. He disks Kansas State University to define soil health 

the sprawling, leafy legume once, then does a more precisely. He can tell that covers improve 

shallow chisel plowing to stop growth and the “flow” of his soil, and he is studying root 

save moisture. Breakdown of the somewhat growth after covers. But he feels her work 

tough stems depends on moisture. 

measuring enzymes and carbon dioxide l 

When he leaves all the cowpea biomass evels will give farmers new ways to evaluate 

in the field, he disks a second time to speed microbial activity and overall “soil health.” 

and rootknot nematode levels in greenhouse 

experiments (351). Despite some research (351) 

showing an increased nematode risk after 

cowpeas, California farmers report no such 

problem (256). 

Crop Systems 

Cowpeas’ heat-loving nature makes them an ideal 

mid-summer replenisher of soil organic matter 

and mineralizable nitrogen. Cowpeas set pods 

over a period of several weeks. Viny varieties 

continue to increase dry matter yields during that 

time. 

A mix of 15 lb. cowpeas and 30 lb. buckwheat/A 

makes it possible to incorporate the 

cover crop in just six weeks while still providing 

some nitrogen. Replacing 10 percent of the 

normal cowpea seeding rate with a fast-growing, 


drought-tolerant sorghum-sudangrass hybrid 

increases dry matter production and helps support 

the cowpea plants for mowing (256). 

Cowpeas also can be seeded with other tall annual 

crops such as pearl millet (see Up-and-Coming 

Cover Crops, p. 158). Overseeding cowpeas into 

nearly mature spring broccoli in June in Zones 5 

and 6 of the Northeast 

suppresses weeds while 

improving soil (302). Planting 

cowpeas in late June or early 

July in the upper Midwest 

after spring canning peas provides 

green manure or an 

emergency forage crop (351). 

Cowpeas can fill a midsummer 

fallow niche in inland North Carolina 

between spring and summer vegetable crops. A 

mix of IRON AND CLAY cowpeas (50 lb./A) and 

German millet (15 lb./A) planted in late June can 

be killed mechanically before no-till transplanted 

fall broccoli.In several years of screening trials at 

the same sites, cowpea dry matter (3,780 lb./A) 

out yielded soybeans (3,540 lb. DM/A), but plots 

of sesbania (Sesbania exaltata) had top yields at 

about 5,000 lb. DM/A (69). 


Cowpeas are more drought tolerant than soybeans, 

but less tolerant of waterlogging (302) and 

Unlike many grain legumes, 

cowpeas can leave a net N 

gain even if seeds are 

harvested. 

frost (211). Sown in July, the cowpea canopy 

closed more rapidly and suppressed weeds better 

than lespedeza (Lespedeza cuneata), American 

jointvetch (Aeschynomene americana), sesbania 

and alyceclover (Alysicarpus spp.), the other 

warm-season legumes tested (351). Cowpeas perform 

better than clovers and alfalfa on poor or 

acid soils. Cowpea residue 

breaks down faster than 

white sweetclover (302) 

but not as fast as Austrian 

winter peas. 

Warm-season alternatives 

to cowpeas include 

two crops that retain some 

cowpea benefits. Buckwheat 

provides good beneficial habitat and 

weed control without attracting stinkbugs. 

Velvetbeans (Mucuna deeringiana) provide nitrogen, 

soil protection and late-season forage in hot, 

long-season areas. They do not attract stinkbugs 

and are resistant to nematodes (81, 263). 

SEED 

Cultivars. See Cultivars for diverse niches 

(p. 96). 

Seed sources. Adams-Briscoe, Frazier, Lohse Mill, 

Mangelsdorf, Peaceful Valley and Pennington. See 

Seed Suppliers (p. 166). 

COWPEAS 99

CRIMSON CLOVER 

Trifolium incarnatum 

Type: winter annual or summer 

annual legume 

Roles: N source, soil builder, erosion 

prevention, reseeding interrow 

ground cover, forage 

Mix with: rye and other cereals, 

vetches, annual ryegrass, subclover, 

red clover, black medic 



not recomended summer annual winter annual 

marginal (limited by heat, rainfall, short season) 

With its rapid, robust growth, crimson 

clover provides early spring nitrogen 

for full-season crops. Rapid fall growth, 

or summer growth in cool areas, also makes it a 

top choice for short-rotation niches as a weedsuppressing 

green manure.Popular as a staple forage 

and roadside cover crop throughout the 

Southeast, crimson clover is gaining increased 

recognition as a versatile summer-annual cover in 

colder regions. Its spectacular beauty when flowering 

keeps it visible even in a mix with other 

flowering legumes, a common use in California 

nut groves and orchards. 

BENEFITS 

Nitrogen source. Whether you use it as a spring 

or fall N source or capitalize on its vigorous 

reseeding ability depends on your location. 

Growers in the “crimson clover zone”—east of 

the Mississippi, from southern Pennsylvania and 

southern Illinois south—choose winter annual 

crimson clover to provide a strong, early N boost. 

In Hardiness Zone 8—the warmer half of the 

Southeast—crimson clover will overwinter 

dependably with only infrequent winterkill. Its N 

contribution is 70 to 150 lb./A. 

Reseeding cultivars provide natural fertility to 

corn and cotton. Crimson clover works especially 

well before grain sorghum, which is planted later 

than corn. It is being tested extensively in no-till 

and zone-till systems. One goal is to manage to let 

the legume reseed yearly for no-cost, season-long 

erosion control, weed suppression and nitrogen 

banking for the next year. 

Along the northern edge of the “crimson clover 

zone,” winterkill and fungal diseases will be more 

of a problem. Hairy vetch is the less risky overwintering 

winter annual legume, here and in 

northern areas. Crimson clover often can survive 

winters throughout the lower reaches of Zone 6, 

especially from southeastern Pennsylvania northeast 

to coastal New England (151). 

Crimson clover is gaining popularity as a 

winter-killed annual,like oats,in Zones 5 and colder. 

Planted in late summer, it provides good 

groundcover and weed control as it fixes nitrogen 

from the atmosphere and scavenges nitrogen 

from the soil. Its winterkilled residue is easy to 

manage in spring. 

Biomass. As a winter annual, crimson clover can 

produce 3,500 to 5,500 lb. dry matter/A and fix 

70 to 150 lb. N/A by mid-May in Zone 8 (the 

inland Deep South). In a Mississippi study, crimson 

clover had produced mature seed by April 21, 

as well as 5,500 lb. DM and 135 lb. N/A. The 

study concluded that crimson clover is one of 


several winter annual legumes that can provide 

adequate but not excessive amounts of N for 

southern grain sorghum production (16, 23, 79). 

Crimson clover has produced more than 7,000 lb. 

DM/A several times in recent years at a USDA-ARS 

site in Beltsville, Md., where it produced 180 lb. N 

and 7,800 lb. DM/A in 1996 (341). 

As a summer annual in lower Michigan, a midsummer 

planting of crimson clover seeded at 20 

lb./A produced 1,500 lb.dry matter and 50 lb.N/A 

by late November (140). 

Companion crop. Crimson clover grows well in 

mixtures with small grains, grasses and other 

clovers. An oats crop is a frequent companion, 

either as a nurse crop to establish a clear stand of 

crimson clover,or as a high-biomass,nutrient-scavenging 

partner. In California, crimson clover is 

planted with rose clover and medics in orchards 

and nut groves to minimize erosion and provide 

some N to tree crops (351). 

In field trials of six annual legumes in 

Mississippi, crimson clover was found to produce 

the most dry matter (5,600 to 6,000 lb./A) compared 

to hairy vetch, bigflower vetch, berseem 

clover, arrowleaf clover (Trifolium vesiculosum) 

and winter peas. It produced 99 to 130 lb. N/A 

and is recommended for soil erosion control 

because of its high early-autumn dry matter production 

(352). 

Beneficial habitat and nectar source. Crimson 

clover has showy, deep red blossoms 1 /2 to 1 inch 

long. They produce abundant nectar, and are 

visited frequently by various types of bees. The 

blooms may contain many minute pirate bugs, an 

important beneficial insect that preys on many 

small pests, especially thrips (351). Georgia 

research shows that crimson clover sustains populations 

of pea aphids and blue alfalfa aphids. 

These species are not pests of pecans,but provide 

alternative food for beneficial predators such as 

lady beetles, which later attack pecan aphids. 

CRIMSON CLOVER (Trifolium incarnatum) 

Nutrient cycler. Crimson clover adds to the soil 

organic N pool by scavenging mineralized N and 

by normal legume N fixation. The scavenging 

process, accomplished most effectively by grasses, 

helps reduce the potential for N leaching into 

groundwater during winter and spring (139,213). 

Mixed with annual ryegrass in a simulated rainfall 

study, crimson clover reduced runoff from the 

herbicide lactofen by 94 percent and norflurazon 

and fluometuron by 100 percent (286). The 

grass/legume mixture combines fibrous surface 

roots with short tap roots. 

MANAGEMENT 


Crimson clover will grow well in about any type 

of well drained soil, especially sandy loam. It may 

fare poorly on heavy clay, waterlogged, extremely 

acid or alkaline soils. Crimson clover establishment 

requires moderate temperature and moisture, 

but seedlings are rather robust thanks to 

crimson clover’s relatively large seed size. Once 

established, it thrives in cool, moist conditions. 

Dry soil often hinders fall plantings in the South. 

Inoculate crimson clover with an R-type (crimson 

clover-berseem) inoculant. Research in 

Alabama showed that deficiencies of phosphorus 

or potassium—or strongly acidic soil with a pH of 

less than 5.0—can virtually shut down N fixation. 

Nodules were not even formed at pH 5.0 in the 

test. Phosphorus deficiency causes many small 

but inactive nodules to form (144). 


CRIMSON CLOVER 101

Winter annual use. Seed six to eight weeks 

before the average date of first frost at 15 to 18 

lb./A drilled, 22 to 30 lb./A broadcast. As with 

other winter legumes, the ideal date varies with 

elevation. In North Carolina, for example, the recommended 

seeding dates are three weeks later 

along the coast than in the mountains. 

Don’t plant too early or crimson clover will go 

to seed in the fall and not regrow in spring until 

the soil warms up enough to germinate seeds. 

Early to mid-August seeding is common in the 

northern part of crimson clover’s winter-annual 

range.While October plantings are possible in the 

lower Mississippi Delta,an August 15 planting in a 

Mississippi test led to higher yields than later 

dates (182). In the lower Coastal Plain of the Gulf 

South, crimson clover can be planted until mid- 

November (277). 

Nutrient release from crimson clover residue— 

and that of other winter annual legumes—is 

quicker if the cover crop is tilled lightly into the 

soil. Apart from erosion concerns, this fertility 

enhancing step adds cost and decreases the 

weed-suppression effect early in the subsequent 

crop’s cycle. 

Summer annual use. In general,plant as soon as 

all danger of frost is past. Spring sowing establishes 

crimson clover for a rotation with potatoes in 

Maine. In Michigan, researchers 

have successfully established 

crimson clover after short-season 

crops such as snap beans (140). 

In Northern corn fields, 

Michigan studies showed that 

crimson clover can be overseeded 

at final cultivation (layby) 

when corn is 16 to 24 inches tall.Crimson clover 

was overseeded at 15 lb./A in 20-inch bands 

between 30-inch rows using insecticide boxes 

and an air seeder.The clover established well and 

caused no corn yield loss (238). Crimson clover 

has proved to be more promising in this niche 

than black medic, red clover or annual ryegrass, 

averaging 1,500 lb. DM/A and more than 50 lb. 

N/A (140). 

In Maine, spring-seeded crimson clover can 

yield 4,000 to 5,000 lb.DM/A by July,adding 80 lb. 

In Hardiness Zone 5 

and colder, crimson 

clover can provide a 

winterkilled mulch. 

N/A for fall vegetables. Mid-July seedings have 

yielded 5,500 lb./A of weed-suppressing biomass 

by late October. Summer-annual use is planned 

with the expectation of winter-kill. It sometimes 

survives the winter even in southern Michigan 

(205), however, so northern experimenters 

should maintain a spring-kill option if icy winds 

and heaving don’t do the job. 

In California, spring sowing often results in 

stunting, poor flowering and reduced seed yield, 

and usually requires irrigation (351). 

Rotations. In the South, crops harvested in early 

fall or sown in late spring are ideal in sequence 

with crimson clover. Timely planting of crimson 

clover and its rapid spring growth can enable it to 

achieve its maximum N contribution,and perhaps 

reseed. While corn’s early planting date and cotton’s 

late harvest limit a traditional winter-annual 

role for crimson clover, strip planting and zone 

tillage create new niches. By leaving unkilled 

strips of crimson clover to mature between zonetilled 

crop rows, the legume sets seed in May. 

The majority of its hard seed will germinate in fall. 

Kill crimson clover before seed set and use 

longer season cultivars where regrowth from 

hard seed would cause a weed problem. 

Researchers have successfully strip-tilled into 

standing crimson clover when 25 to 80 percent of 

the row width is desiccated with 

a herbicide or mechanically tilled 

for the planting area. Narrower 

strips of crimson clover increased 

weed pressure but reduced moisture 

competition, while wider 

strips favored reseeding of the 

cover (187, 353). 

In a crimson clover-before-corn system, growers 

can optimize grain yields by no-tilling into 

the crimson clover and leaving the residue on 

the surface, or optimize total forage yield by harvesting 

the crimson clover immediately before 

planting corn for grain or silage (160). In 

Mississippi, sweet potatoes and peanuts suffered 

no yield or quality penalty when they were 

no-tilled into killed crimson clover. The system 

reduced soil erosion and decreased weed competition 

(21). 


In Ohio, crimson clover mixed with hairy 

vetch, rye and barley provided a fertility enhancing 

mulch for no-till processing tomato transplants. 

Use of a prototype undercutter implement 

with a rolling harrow provided a good kill. 

Because the wide blades cut just under the soil 

surface on raised beds, they do not break stalks, 

thus lengthening residue durability. The longlasting 

residue gave excellent results, even under 

organic management without the herbicides, 

insecticides or fungicides used on parallel plots 

under different management regimes. Nancy 

Creamer at the University of North Carolina is 

continuing work on the undercutter and on cover 

crops in organic vegetable systems (72). 

Mixed seeding. For cover crop mixtures, sow 

crimson clover at about two-thirds of its normal 

rate and the other crop at one third to one-half of 

its monoculture rate. Crimson 

clover development is similar to 

tall fescue. It even can be established 

with light incorporation 

in existing stands of aggressive 

grasses after they have been 

closely mowed or grazed. 

Reseeding. Overwintered crimson clover needs 

sufficient moisture at least throughout April to 

produce seed. Cultivar selection is critical when 

early spring maturity is needed. 

DIXIE and CHIEF are full-season standards. AU 

ROBIN and FLAME beat them by about two weeks, 

while the popular TIBBEE is about a week ahead of 

the standards. A new cultivar—AU CRIMSON, that 

reportedly would be three weeks earlier—is still 

under development. Price varies more by seasonal 

supply than by cultivar. 

Killing. Its simple taproot makes crimson clover 

easy to kill mechanically. Mowing after early bud 

stage will kill crimson clover. Maximum N is 

available at late bloom or early seed set, even 

before the plant dies naturally. Killing earlier 

yields less N—up to 50 lb. N/A less at its late vegetative 

stage, which is about 30 days before early 

seed set (283). 

In Mississippi, crimson 

clover produced mature 

seed and 135 lb. N/A 

by April 21. 

A rolling stalk chopper flattens a mix of crimson 

clover, hairy vetch and rye ahead of no-till 

vegetable transplanting at Steve Groff’s farm in 

southeastern Pennsylvania.The crimson is killed 

completely if it is in full bloom; and even early 

bloom is killed better than vegetative crimson. 

Small amounts of metribuzin applied two to 

three weeks after transplanting handle any 

regrowth and provide season-long weed control, 

as well (132). Glufosinate-ammonium, paraquat, 

cyanazine and glyphosate are other herbicides 

used to kill crimson clover (205). 


Crimson clover is a secondary host to plant pests 

of the Heliothus species, which include corn earworm 

and cotton bollworm. Despite its known 

benefits,crimson clover has been eradicated from 

many miles of roadsides in Mississippi at the 

request of some Delta farmers 

who suspect it worsens problems 

from those pests (77). 

Crimson clover doesn’t significantly 

increase risk of 

Southern corn rootworm in notill 

corn, while hairy vetch does 

(47). It is more resistant to diseases 

(351) and to some nematodes than other 

clovers (276). Crimson clover is said to tolerate 

viral diseases, but it succumbed to virus in July 

plantings in Mississippi (182) and to Sclerotinia 

in fall plantings in Maryland (83). 

In lab tests, crimson clover, berseem clover and 

hairy vetch have been shown to inhibit germination 

and seedling development of onion, carrot 

and tomato (26). However, this interference hasn’t 

been observed in North Carolina field crops 

where strips are mechanically tilled (353), or in 

other studies with crimson clover as part of a 

killed organic mulch. No-till vegetable transplanting 

has been done successfully on the same day 

as mechanically killing the cover crop mix on 

Steve Groff’s Lancaster County, Pa., farm with no 

negative effects (132). 

Wait two to three weeks after incorporating 

covers before planting seeds,to allow the biomass 

to begin to decompose and the soil biological life 

CRIMSON CLOVER 103

to stabilize. During this time, a flush of bacteria 

such as Pythium and Rhizoctonia attack rapidly 

decaying plants. These bacteria also can attack 

seedling crops. To plant more quickly, mow the 

clover and use row cleaners to clear the tops from 

the seed zone. The mow/wait/plant cycle also 

may be influenced by the need to wait for rain to 

increase seedbed moisture. 

Mixed with hairy vetch, crimson clover attracts 

beneficial insects, provides nitrogen and suppresses 

weeds in Oklahoma’s native and plantation 

pecan groves. Both legumes go to seed and 

then are harvested for forage. Arrowleaf clover 

provided more biomass and N, but didn’t work as 

well for insect pest management (320) and is very 

susceptible to root knot nematode. 

Crimson clover harbors flower thrips and is a 

more likely host for tarnished plant bug than 

hairy vetch or subterranean clover (38). Intensive 

screenings show less abundant arthropod herbivores 

and predators on crimson clover than on 

hairy vetch (162). 

Tillage practices and residue management variations 

(no-till, incorporate, removal) of cover 

cropped lupin, rye, hairy vetch or crimson clover 

had little consistent effect on nematodes in north 

Florida corn fields (212). 

Other Options 

Pasture and hay crop. Crimson clover is excellent 

for grazing and haying.It will regrow if grazed 

or mowed no lower than 3 or 4 inches before the 

early bud stage. Mixing with grass reduces its relatively 

low bloat risk even further. Seedheads are 

easily accessible by grazing livestock, leading to 

reseeding via cattle manure.Timely mowing four 

to six weeks before bloom improves growth, 

reduces lodging and will cause more uniform 

flowering and seed ripening on highly fertile soils 

(91, 351). 

Crimson clover can be grazed lightly in the fall, 

more intensively in the spring and still be left to 

accumulate N and/or set seed with little reduction 

in its soil N contribution (60). 


Crimson clover is: 

• less tolerant of mowing than are subclovers or 

medics (351) 

• similar to hairy vetch and Austrian winter pea 

in the Southeast for total N production 

• quicker-growing than hairy vetch in fall and 

spring 

• a better weed suppressor in fall than hairy 

vetch 

• earlier to mature in spring than hairy vetch 

Crimson clover produces more dry matter than 

sweetclover or hairy vetch on a given amount of 

rainfall. 

SEED 

Cultivars. See Reseeding (p. 103) for cultivar 

comparisons. 

Seed Sources. Forage suppliers, including 

Ampac, Kaufman, Missouri Southern, Peaceful 

Valley, Pennington and Sexauer. See Seed 

Suppliers (p. 166). 


FIELD PEAS 

Pisum sativum subsp. arvense 

Also called: Austrian winter peas 

(black peas), Canadian field peas 

(spring peas) 

Type: summer annual and winter 

annual legume 

Roles: plow-down N source, weed 

suppressor, forage 

Mix with: strong-stemmed wheat, 

rye, triticale or barley for vertical 

support 



summer annual 

winter annual 

High N-fixers, field peas produce abundant 

vining forage and contribute to shortterm 

soil conditioning. Succulent stems 

break down easily and are a quick source of available 

N (302). Field peas grow rapidly in the cool, 

moist weather they encounter as winter annuals 

in the South and in parts of Idaho, and as earlysown 

summer annuals in the Northeast, North 

Central and Northern Plains areas. Harvest 

options as high-quality forage and seed increase 

their value. 

Winter-hardy types of field peas, especially 

Austrian winter peas, can withstand temperatures 

as low as 10 F with only minor injury, but 

they don’t overwinter consistently in areas colder 

than moderate Hardiness Zone 6.They are sensitive 

to heat, particularly in combination with 

humidity. They tend to languish in mid-summer 

even in the cool Northeast (302), where average 

summers have fewer than 30 days exceeding 86 F. 

Temperatures greater than 90 F cause flowers to 

blast and reduce seed yield. On humus-rich black 

soils, field peas will produce abundant viny 

growth with few seed pods. 

Use in the East and Southeast is limited by field 

peas’ susceptibility to Sclerotinia crown rot, 

which can destroy whole fields during winter in 

the mid-Atlantic area.Risk of infection increases if 

pea crops are grown on the same land in close 

rotation (82). 

Canadian field peas are a related strain of 

vining pea. These annual “spring peas” can outgrow 

spring-planted winter peas. They often 

are seeded with triticale or another small grain. 

Spring peas have larger seeds, so there are fewer 

seeds per pound and seeding rates are higher, 

about 100 to 160 lb./A (237). However, spring 

pea seed is a bit less expensive than Austrian 

winter pea seed (347). TRAPPER is the most common 

Canadian field pea cultivar. 

This section focuses on the widely grown 

Austrian winter pea. “Field peas” refers to both 

the winter and spring types. 

BENEFITS 

Bountiful biomass. Under a long, cool, moist 

season during their vegetative stages, Austrian 

winter peas produce more than 5,000 lb.dry matter/A, 

even when planted in spring in colder 

climates. Idaho farmers regularly produce 6,000 

to 8,000 lb. DM/A from fall-planted Austrian 

FIELD PEAS 105

winter peas (135). Because the residue breaks 

down quickly, only peas in the high-production 

areas build up much long-term organic matter. 

Peas do not make a good organic mulch for weed 

control (302). 

Nitrogen source. Austrian winter peas are top N 

producers, yielding from 90 to 150 lb. N/A, and at 

times up to 300 lb. N/A. 

Plowed down as green manure, fall-planted 

legume crops of Austrian winter pea, alfalfa and 

hairy vetch each produced enough N for the production 

of high-quality muskmelons under plastic 

mulch and drip irrigation in a Kansas study.Melon 

yields produced with the legumes were similar to 

those receiving synthetic fertilizer at 63 and 90 lb. 

N/A. The winter peas in the experiment produced 

96 lb.N/A the first year and 207 lb.N/A the 

second (317). 

Austrian winter peas harvested as hay then 

applied as mulch mineralized N at more than 

double the rate of alfalfa hay. The N contribution 

was measured the summer after a fall plowdown of 

the residue.The estimated N recovery of Austrian 

winter pea material 10 months after incorporation 

was 77 percent—58 percent through spring wheat 

and 19 percent in the soil (202). 

Austrian winter pea green manure provided the 

highest spring wheat yield the following year in a 

Montana trial comparing 10 types of medics, 

seven clovers, yellow biennial sweet clover and 

three grains. Crops that produced higher tonnage 

of green manure usually had a negative effect on 

the subsequent wheat crop due to moisture deficiency 

that continued over the winter between 

the crops (314). Field peas can leave 80 lb. N/A if 

terminated at mid-season in lieu of summer fallow 

in dryland areas, or leave more than 30 lb. N/A 

after pea harvest at season’s end (53). 

A winter pea green manure consistently resulted 

in higher malting barley protein content than 

that following other legumes or fallow in a 

Montana trial. Annual legumes harvested for 

seed left less soil N than did plots in fallow. Also 

tested were fava bean,lentil,chickpea,spring pea, 

winter pea hay and dry bean (210). 

Rotational effects. Pulse crops (grain legumes 

such as field peas, fava beans and lentils) improved 

sustainability of dryland crop rotations by providing 

disease suppression, better tilth and other 

enhancements to soil quality in a Saskatchewan 

study. Even at rates of 180 lb. N/A, fertilizer alone 

was unable to bring yields of barley planted into 

barley residue to the maximum achieved from 

these pulse residues (128). 

Water thrifty. In a comparison of water use 

alongside INDIANHEAD lentils and GEORGE black 

medic, Austrian winter pea was the most moisture-efficient 

crop in producing biomass. Each 

crop had used 4 inches of water when Austrian 

winter pea vines were 16 inches long, the lentils 

were 6 to 8 inches tall and the black medic central 

tillers were 4 inches tall (316). 

Austrian winter peas grown in a controlled 

setting at 50 F recorded more than 75 percent of 

its N2 fixed per unit of water used by the 63rd 

day of growth. White clover, crimson clover and 

hairy vetch reached the same level of water efficiency, 

but it took 105 days (273). 

Quick growing. Rapid spring growth helps peas 

out compete weeds and make an N contribution 

in time for summer cash crops in some areas. 

Forage booster. Field peas grown with barley, 

oat, triticale or wheat provide excellent livestock 

forage. Peas slightly improve forage yield, but significantly 

boost protein and relative feed value of 

small grain hay. 

Seed crop. Seed production in Montana is about 

2,000 lb./A. In the Pacific Northwest, market 

prices have ranged up to $11 per hundred 

weight. University of Montana economists estimate 

potential gross returns of $83 to $165/A on 

yields of only 1,500 lb./A. Demand is growing for 

field peas as food and livestock feed (53). 

Long-term bloomer.The purple and white blossoms 

of field peas are an early and extended 

source of nectar for honeybees. 


Chill tolerant. Austrian winter pea plants may 

lose some of their topgrowth during freezes, but 

can continue growing after temperatures fall as 

low as 10 F. Their shallow roots and succulent 

stems limit their overwintering ability, however. 

Sustained cold below 18 F without snow cover 

usually kills Austrian winter pea (158). To maximize 

winter survival: 

• Select the most winter-hardy cultivars available—GRANGER,MELROSE 

and COMMON WINTER. 

• Seed early enough so that plants are 6 to 8 

inches tall before soil freezes,because peas are shallow 

rooted and susceptible to heaving. Try to plant 

from mid-August to mid-September in Zone 5. 

• Plant into grain stubble or a rough seedbed, 

or interseed into a winter grain. These environments 

protect young pea roots by suppressing 

soil heaving during freezing and thawing. 

Trapped snow insulates plants, as well. 

MANAGEMENT 


Peas prefer well-limed, well-drained clay or heavy 

loam soils,near-neutral pH or above and moderate 

fertility. They also do well on loamy sands in 

North Carolina (282).Field peas usually are drilled 

1 to 3 inches deep to ensure contact with moist 

soil and good anchoring for plants. 

If you broadcast peas, incorporation will greatly 

improve stands,as seed left exposed on the surface 

generally does not germinate well. Longvined 

plants that are shallow-seeded at low seeding 

rates tend to fall over (lodge), lay against the 

soil and rot. Combat this tendency by planting 

with a small grain nurse crop such as oats, wheat, 

barley,rye or triticale.Reduce the pea seeding rate 

by about one quarter—and grain by about one 

third—when planting a pea/grain mix. 

Planted at 60 to 80 lb./A in Minnesota, Austrian 

winter peas make a good nurse crop for alfalfa (274). 

Field pea seed has a short shelf life compared 

with other crops.Run a germination test if seed is 

more than two years old and adjust seeding rate 

accordingly. If you haven’t grown peas in the 

seeded area for several years, inoculate immediately 

before seeding. 

FIELD PEAS (Pisum sativum subsp. arvense) 

West. In mild winter areas of California and 

Idaho,fall-plant for maximum yield.In those areas, 

you can expect spring-planted winter peas to 

produce about half the biomass as those that are 

fall-planted. Seed by September 15 in Zone 5 of 

the Inter-Mountain region in protected valleys 

where you’d expect mild winter weather and 

good, long-term snow cover. October-planted 

Austrian winter pea in the Zone 9 Sacramento 

Valley of California thrive on cool, moist conditions 

and can contribute 150 lb. N/A after being 

flail-mowed and disked in early April. 

The general rule for other parts of the semi-arid 

West where snow cover is dependable is to plant 

peas in the fall after grain harvest. In these dry 

regions of Montana and Idaho, overseed peas at 

90 to 100 lb./A by “frostseeding” any time soils 

have become too cold for pea germination. Be 

sure residue cover is not too dense to allow seed 

to work into the soil through freeze/thaw cycles 

as the soil warms (316). 

In the low-rainfall Northern Plains, broadcast 

clear stands of peas in early spring at a similar rate 

for the “Flexible Green Manure” cropping system 

(below). Seeding at about 100 lb./A compensates 

somewhat for the lack of incorporation and provides 

strong early competition with weeds (316). 

Plant as soon as soil in the top inch reaches 40 F 

to make the most of spring moisture (53). 


FIELD PEAS 107

A mixture of Austrian winter peas and a small 

grain is suitable for dryland forage production 

because it traps snow and uses spring moisture to 

produce high yields earlier than spring-seeded 

annual forages (53). With sufficient moisture, 

spring peas typically produce higher forage yields 

than Austrian winter peas. 

East. Planted as a companion crop in early spring 

in the Northeast, Austrian winter peas may provide 

appreciable plowdown N for summer crops 

by Memorial Day (302). In the mid-Atlantic, 

Austrian winter peas and hairy vetch planted Oct. 

1 and killed May 1 produced about the same total 

N and corn yields (83). 

Southeast. Seed by October 1 in the inland Zone 

8 areas of the South so that root crowns can 

become established to resist heaving.Peas produce 

more biomass in the cooler areas of the South than 

where temperatures rise quickly in spring (53, 

302). Peas planted in late October in South 

Carolina’s Zone 8 and terminated in 

mid- to late April produce 2,700 to 

4,000 lb. dry matter/A (17). 

Killing 

Peas are easily killed by disking or 

mowing after full bloom, the stage 

of maturity that provides the optimum N contribution. 

Disk lightly to preserve the tender residue 

for some short-term erosion control. 

The downside to the quick breakdown of pea 

vines is their slimy condition in spring if they winterkill, 

especially in dense, pure stands. Planting 

with a winter grain provides some protection 

from winterkill and reduces matting of dead pea 

vegetation (230). 

Winter pea residue 

breaks down and 

releases N quickly. 

the seed with a shallow pass of his field cultivator. 

They grow 3 to 6 inches tall before going dormant 

in late December in his Zone 8 location about 75 

miles north of the Gulf of Mexico. Quick regrowth 

starts about the third week in January. He kills 

them in mid-April by disking, then shallow plows 

to incorporate the heavy residue (158). 

Farmers and researchers note several IPM 

cautions, because Austrian winter peas: 

• Host some races of nematodes 

• Are susceptible to winter Sclerotinia crown 

rot, Fusarium root rot as well as seed rot and 

blights of the stem, leaf or pod 

• Are variably susceptible to the Ascochyta 

blight (MELROSE cultivar has some resistance) 

• Host the pathogen Sclerotinia minor.There 

was a higher incidence of leaf drop in 

California lettuce planted after Austrian winter 

peas in one year of a two-year test (185). 

Austrian winter peas were heavily damaged by 

Sclerotinia trifoliorum Eriks in several years of a 

four-year study in Maryland, but the crop still produced 

from 2,600 to 5,000 lb. dry 

matter/A per year in four out of 

five years. One year DM production 

was only 730 lb./A. Mean N 

contribution despite the disease 

was 134 lb. N/A. Overall, Austrian 

winter peas were rated as being 

more suited for Maryland Coastal Plain use than in 

the Piedmont, due to harsher winters in the latter 

location (160). 

To combat disease, rotate cover crops to avoid 

growing peas in the same field in successive years. 

To minimize disease risk, waiting several years is 

best. To minimize risk of losing cover crop 

benefits to Sclerotinia disease in any given season, 

mix with another cover crop such as cereal rye. 


Winter peas break crop disease cycles,Ben Burkett 

of Petal, Miss., has found. Septoria leaf spot problems 

on his cash crops are reduced when he plants 

Austrian winter pea in fall after snap beans and 

ahead of collards and mustard greens the next summer. 

Between October 15 and November 15, 

Burkett broadcasts just 50 lb./A then incorporates 

Crop Systems 

Northern Plains. Austrian winter pea is a top 

candidate for dryland grain legume>cereal rotations 

designed to save N and be adaptable to 

varying amounts of soil moisture. The sequence 

starts with a spring- or fall-planted grain legume 

whose residue substitutes for fallow, followed by 

the usual local small grain. 


In a “Flexible Green Manure” cropping system, 

the guiding management principles call for the 

grain legume to be controlled based on the: 

• season’s rainfall 

• crop’s N fixation 

• anticipated moisture and N need of the 

following crop 

When managing for moisture, farmers look at 

three management paths for their Austrian winter 

peas or other grain legume: 

• Deficient moisture—incorporate the grain 

legume early to initiate summer fallow. 

• Adequate moisture—terminate the grain 

legume when about 4 inches of groundwater 

have been used. Residue is maintained for 

green manure, moisture retention and erosion 

prevention. 

• Above-average moisture—crop is left to 

bear seed for harvest. 

In conventional fallow systems using tillage or 

herbicide, soil is left unplanted to allow organic 

matter to mineralize during a non-crop year to 

increase available plant nutrients. Fallow systems, 

however, still require N fertilizer to compensate 

for the net loss of native soil fertility and have 

led to many environmental problems. These 

include saline seep and nitrate pollution 

of groundwater due to 

leaching of nutrients during the 

fallow period. 

Grain legumes provide a soilprotecting 

alternative that more N 

than fallow. The legumes also disrupt 

disease, insect and weed 

cycles and contribute to long-term soil-building 

where limited moisture slows organic matter 

breakdown. Austrian winter peas work in these 

rotations where there is at least 18 inches of rain 

per year. INDIANHEAD lentils (Lens culinaris 

Medik), a specialty lentil for cover crop use, is 

widely used in this system. 

Montana research shows that when soil moisture 

is replenished by winter precipitation, annual 

legumes can substitute for fallow without 

significantly reducing the yield of the next barley 

crop. When the legume generates income from 

harvest of its hay or grain,fertilizer N savings from 

In the Northeast, 

spring-planted peas 

can be incorporated 

by Memorial Day. 

the legume year’s contribution to the small grain 

may top $15/A (316). 

In Idaho, fall-seeded Austrian winter peas harvested 

for seed provided income, residual N from 

the pea straw and soil disease suppression in 

a study of efficient uses of the legume cover. A 

crop rotation of Austrian winter pea>winter 

wheat>spring barley produced similar wheat 

yields as did using the peas as green manure or 

allowing soil organic matter to break down 

during summer fallow in the first year. While 

neither Austrian winter pea green manure nor fallow 

produced income, the green manure 

improved soil organic matter and added more N 

for wheat than did summer fallow. Fallow caused 

a net soil capacity loss by “mining” finite soil 

organic matter reserves (201). 

In a northern Alberta comparison of conventional 

(tilled), chemical (herbicide) and green 

(field pea) fallow systems, spring-planted field 

peas provided 72 lb. N/A, significantly more than 

the other systems.The field pea system was also 

more profitable when all inputs were considered, 

providing higher yield for two subsequent cash 

crops, higher income and improvement of soil 

quality (8). 

Southeast. Fall-seeded Austrian 

winter peas out-produced hairy 

vetch by about 18 percent in both 

dry matter and N production in a 

three-year test in the Coastal Plain 

of North Carolina.When legumes 

were grown with rye, wheat or 

spring oats,Austrian winter pea mixtures also had 

the highest dry matter yields. Over the three 

years, Austrian winter peas ranked the highest 

(dry-matter and N) in the legume-only trials and as 

the legume component of the legume/grain mixtures. 

In descending order after the peas were 

hairy vetch, common vetch and crimson clover. 

The peas were sown at 54 lb./A in the sole-seedings 

and 41 lb./A in mixtures (285). 

In the year of greatest N fixation, soil N in the 

Austrian winter peas mixture treatments was 50 

percent greater than the average of all other treatments. 

Researchers noted that the bottom leaves 

FIELD PEAS 109

Peas Do Double Duty for Kansas Farmer 

PARTRIDGE, Kan.—Jim French figures Austrian 

winter peas provide free grazing, free nitrogen, 

or both.The vining legume produces just as 

much N for the following grain sorghum crop 

even if he lets his registered Gelbvieh herd eat 

all they want of the winter annual’s spring 

growth. 

French farms on flat, well-drained sandy 

loam soil near Partridge, Kan. He manages 

about 640 acres each of cash crops (winter 

wheat and grain sorghum) and forages (alfalfa, 

sudangrass, winter peas and cowpeas, and an 

equal area in grass pasture). Peas follow wheat 

in the three-year crop rotation on his southcentral 

Kansas farm. He chisel plows the 

wheat stubble twice about 7 inches deep, 

disks once to seal the surface, then controls 

weeds as necessary with a light field cultivator. 

Between mid-September and mid-October 

he inoculates about 30 lb./A of the peas and 

drills them with an old John Deere double-run 

disk drill in 8-inch rows. Establishment is 

usually good, with his only anxiety coming 

during freeze-thaw cycles in spring.“Each time 

the peas break dormancy, start to grow, then 

get zapped with cold again they lose some of 

their root reserves and don’t have quite the 

resistance to freezing they did.They’ll sprout 

back even if there’s vegetative freeze damage 

as long as their food reserves hold out,” French 

reports. 

Ironically, this spring freezing is less of a 

problem further north where fields stay frozen 

longer before a slower thaw.This works as 

long as snow cover protects the peas from the 

colder early and mid-winter temperatures. In 

most years, he sets up temporary fence and 

turns his cattle into the peas about April 1 at 

the stocking rate of two animal units per acre. 

During the best years of mild weather and 

adequate moisture,“the cattle have a hard time 

keeping up,” says French. Depending on his 

need for forage or organic matter, he leaves 

the cattle in until he incorporates the pea 

stubble, or gives it time to regrow. 

One reason he gets about the same 90 to 120 

lb. N/A contribution with or without grazing is 

that the winter pea plants apparently continue 

N fixation and root growth while being grazed. 

Soil tests show that 25 to 30 lb. N/A are 

available in the nitrate form at incorporation in 

late spring, with the balance in an organic form 

that mineralizes over the summer. Grazing the 

peas helps to contain cheatgrass, which tends 

to tie up N if it’s incorporated just ahead of his 

sorghum crop. 

French is sold on winter peas ahead of his 

grain sorghum because it provides N while 

reducing weed pressure from cheatgrass and 

pigweed and decreasing lodging from 

charcoal root rot.The option to use the 

peas as forage—while still achieving adequate 

sorghum yield—lets him buy less processed 

feed, improves livestock health and accelerates 

conversion of the peas’ organic material into 

available soil nutrients. 

“Winter peas work best where you integrate 

crops and livestock,” says French.“They give 

you so many benefits.” 

of pea vines were more decomposed than other 

legumes, giving the crop an earlier start in N contribution. 

Further, soil N in the upper 6 inches of 

soil under the Austrian winter peas held 30 to 50 

percent of the total soil inorganic N in the winter 

pea treatments, compared with levels of less than 

30 percent in the top soil layer for all other treatments. 

In situations where the early-summer N 

release from peas could be excessive, mixing 

Austrian winter peas with a grain can moderate 

the N contribution and slow down its release into 

the soil (285). 

The carbon to nitrogen (C:N) ratio of plant matter 

is an indication of how rapidly vegetation will 

break down. Mixtures of small grains with 

Austrian winter peas and the vetches had C:N 


values from 13 to 34,but were generally under 25 

to 30, the accepted threshold for avoiding net 

immobilization of N (285). 

Austrian winter peas and crimson clover can 

provide adequate N for conventionally planted 

cotton in South Carolina. In a three-year trial, fertilizer 

rates of up to 150 lb.N/A made no improvement 

to cotton yield on the pea plots. The 

evaluation showed that soil nitrate under Austrian 

winter peas peaked about nine weeks after incorporation 

(16). 

Austrian winter peas achieved 50 to 60 percent 

groundcover when they were overseeded at 

about 75 lb./A into soybeans at leaf yellowing in 

southeastern Pennsylvania, where they can survive 

some winters. The peas produced nearly 2 

tons of dry matter and 130 lb. N/A by May 20 in 

this test (147). Overseeding peas into corn at last 

cultivation is not recommended due to poor 

shade tolerance. 

Austrian winter peas,like other 

hollow-stemmed succulent covers 

such as vetch and fava beans, 

do not respond well to mowing 

or cutting after they begin to 

bloom. In their earlier stages, 

Austrian winter peas will regrow 

even when grazed several times. See Peas Do 

Double Duty for Kansas Farmer (p. 110). 

After three years of moisture testing, Kansas 

farmer Jim French can explain why he sees more 

soil moisture after spring grazing than when the 

peas are left to grow undisturbed. “There’s 

decreasing overall transpiration because there’s 

less leaf area to move moisture out of the soil into 

the air. Yet the root mass is about the same.” 

Ungrazed peas pump more water as they keep 

growing. 

Other Options 

Harvest field peas for hay when most of the pods 

are well formed. Use a mower with lifting guards 

and a windrow attachment to handle the sprawling 

vines. 


Field peas won’t tolerate field traffic due to 

succulent stems (147). When selecting types, 

remember that long-vined varieties are better for 

weed control than short-vined types. 

SEED 

In dryland systems, 

winter peas produce 

abundant biomass 

with limited moisture. 

Cultivars. MELROSE, known for its winterhardiness, 

is a cultivar of the Austrian winter pea type. 

Planted the first week of September in Idaho, 

MELROSE peas yielded 300 lb.N/A and 6 tons of dry 

matter the next June. Planted in 

mid-April, the cultivar yielded 

“just” 175 lb. N/A and 3.5 T dry 

matter/A (158). 

GRANGER is an improved 

winter pea that has many fewer 

leaves and more tendrils, which 

are stiffer than standard cultivars. 

It is more upright and its pods dry more 

quickly than other winter pea types. Seed is 

expected to be commercially available in 1999 

(232). MAGNUS field peas have out-produced 

Austrian winter peas in California (168) and 

bloom up to 60 days earlier (256). 

Seed sources. Forage crop suppliers, and 

Albright, Ampac, Ernst, Fedco, Lohse, Peaceful, 

Tennessee,Timeless and Wolf. See Seed Suppliers 

(p. 166). 

FIELD PEAS 111

HAIRY VETCH 

Vicia villosa 

Type: summer annual or winter 

annual legume 

Roles: N source, weed suppressor, 

topsoil conditioner 

Mix with: strong-stemmed grains, 

field peas, bell beans, crimson 

clover 

vetch superior 



vetch, crimson 

transition zone 

vetch viable crimson 

clover superior 

hairy vetch viable 

w/irrigation 

Few legumes match hairy vetch for spring 

residue production or nitrogen contribution. 

Widely adapted and winter hardy 

through the warmer parts of Hardiness Zone 4, 

hairy vetch is a top N provider in temperate 

regions. 

The cover grows slowly in fall, but root development 

continues over winter. Growth quickens 

in spring, when hairy vetch becomes a sprawling 

vine up to 12 feet long. Field height rarely 

exceeds 3 feet unless the vetch is supported by 

another crop. Its abundant, viny biomass can be a 

benefit and a challenge. The stand smothers 

spring weeds, however, and can help you replace 

all or most N fertilizer needs for late-planted 

crops. 

BENEFITS 

Nitrogen source. Hairy vetch delivers plenty of 

residue to condition soil and heavy contributions 

of N in mineralizable form (readily available to the 

following cash crop). It can provide sufficient N 

for many vegetable crops, partially replace N fertilizer 

for corn or cotton and increase the crop’s 

N efficiency for higher yield. 

In some parts of California (168) and the East in 

Zone 6, hairy vetch provides its maximum N by 

safe corn planting dates. In Zone 7 areas of the 

Southeast, the fit is not quite as good, but substantial 

N from vetch is often available before 

corn planting (287). 

Corn planting date comparison trials with 

cover crops in Maryland show that planting as 

late as May 15—the very end of the month-long 

local planting period—optimizes corn yield and 

profit from the system. Spring soil moisture was 

higher under the vetch than under cereal rye or 

with no cover crop. Killed vetch left on the surface 

conserved summer moisture for improved 

corn production (60, 62, 64, 82, 136, 192). 

Even without crediting its soil-improving benefits, 

hairy vetch increases N response and produces 

enough N to pay its way in many systems. 

Hairy vetch without fertilizer was the preferred 

option for “risk-averse” no-till corn farmers in 

Georgia, according to calculations comparing 

costs, production and markets during the test. 

The economic risk comparison included crimson 

clover, wheat and winter fallow. Profit was 

higher, but less predictable, if 50 pounds of N 

were added to the vetch system (250). 

Hairy vetch ahead of no-till corn was also the 

preferred option for risk averse farmers in a three- 

Note: To estimate hairy vetch N contribution in 

pounds per acre, cut and weigh fresh vetch top 

growth from a 4-foot by 4-foot area. Multiply by 12 

pounds to gauge available N, by 24 to find total N 

(310). See also How Much N (p. 22). 


year Maryland study that also included fallow and 

winter wheat ahead of the corn. The vetch>corn 

system maintained its economic advantage when 

the cost of vetch was projected at maximum historic 

levels, fertilizer N price was decreased, and 

the herbicide cost to control future volunteer 

vetch was factored in (136). In a related study on 

the Maryland Coastal Plain, hairy vetch proved to 

be the most profitable fall-planted, spring desiccated 

legume ahead of no-till corn, compared with 

Austrian winter peas and crimson clover (192) 

In Wisconsin’s shorter growing season, hairy 

vetch planted after oat harvest provided a gross 

margin of $153/A in an oat/legume>corn rotation. 

Profit was similar to using 160 lb. N/A in 

continuous corn, but with savings on fertilizer 

and corn rootworm insecticide (328). 

Hairy vetch provides yield improvements 

beyond those attributable to N alone. These 

may be due to mulching effects, soil structure 

improvements leading to better moisture retention 

and crop root development, soil biological 

activity and/or enhanced insect populations just 

below and just above the soil surface. 

Soil conditioner. Hairy vetch can improve root 

zone water recharge over winter by reducing 

runoff and allowing more water to penetrate the 

soil profile (108). Adding grasses that take up a 

lot of water can reduce the amount of infiltration 

and reduce the risk of leaching in soils with excess 

nutrients. Hairy vetch—especially an oats/hairy 

vetch mix—decreased surface ponding and soil 

crusting in loam and sandy loam soils. Researchers 

attribute this to dual cover crop benefits:their ability 

to enhance the stability of soil aggregates (particles), 

and to decrease the likelihood that the 

aggregates will dissolve in water (108). 

Hairy vetch improves topsoil tilth, creating a 

loose and flowable soil structure. Vetch doesn’t 

build up long-term soil organic matter due to its 

tendency to break down completely. Vetch is a 

succulent crop, with a relatively “low” carbon to 

nitrogen ratio. Its C:N ratio ranges from 8:1 to 

15:1, expressed as parts of C for each part of N. 

Rye C:N ratios range from 25:1 to 55:1, showing 

why it persists much longer under similar conditions 

than does vetch. Residue with a C:N ratio of 

HAIRY VETCH (Vicia villosa) 

25 or more tends to immobilize N.For more information, 

see How Much N (p. 22), and the rest of 

that section,Building Soil Fertility and Tilth with 

Cover Crops (p. 16). 

Early weed suppression. The vigorous spring 

growth of hairy vetch out-competes weeds, filling 

in where germination may be a bit spotty.Residue 

from killed hairy vetch has a weak allelopathic 

effect,but it smothers early weeds mostly by shading 

the soil. Its effectiveness wanes as it decomposes, 

falling off significantly after about three or 

four weeks.For optimal weed control with a hairy 

vetch mulch, select crops that form a quick 

canopy to compensate for the thinning mulch or 

use high-residue cultivators made to handle it. 

Mixing rye and crimson clover with hairy vetch 

(seeding rates of 30,10,and 30 lb./A,respectively) 

extends weed control to five or six weeks, about 

the same as an all-rye mulch. Even better, the mix 

provides a legume N boost,protects soil in fall and 

over winter better than legumes, yet avoids the 

potential crop-suppressing effect of a pure rye 

mulch on some vegetables (338). 

Good with grains. For greater control of winter 

annual weeds and longer-lasting residue, mix 

hairy vetch with winter cereal grains such as rye, 

wheat or oats. 


HAIRY VETCH 113

Growing grain in a mixture with a legume not 

only lowers the overall C:N ratio of the combined 

residue compared with that of the grain, it may 

actually lower the C:N ratio of the small grain 

residue as well. This internal change causes the 

grain residue to break down faster, while accumulating 

the same levels of N as it did in a monoculture 

(285). 

Moisture-thrifty. Hairy vetch is more droughttolerant 

than other vetches. It needs a bit of moisture 

to establish in fall and to resume vegetative 

growth in spring, but relatively little over winter 

when above-ground growth is minimal. 

Phosphorus scavenger. Hairy vetch showed 

higher plant phosphorus (P) concentrations than 

crimson clover, red clover or a crimson/ryegrass 

mixture in a Texas trial.Soil under hairy vetch also 

had the lowest level of P remaining after growers 

applied high amounts of poultry litter prior to 

vegetable crops (92). 

Fits many systems. Hairy vetch is ideal ahead of 

early-summer planted or transplanted crops, providing 

N and an organic mulch. Some Zone 5 

Midwestern farmers with access to low-cost seed 

plant vetch after winter grain harvest in mid-summer 

to produce whatever N it can until it winterkills—or 

survives to regrow in spring. 

Widely adapted. Its high N production, vigorous 

growth, tolerance of diverse soil conditions, low 

fertility need and winter hardiness make hairy 

vetch the most widely used of winter annual 

legumes. 

MANAGEMENT 


Seed into freshly prepared and firmed soil. 

Broadcast and incorporate lightly to no more than 

1 1 /2 inches deep.Dry conditions often reduce germination 

of hairy vetch. Drill seed at 15 to 20 

lb./A, broadcast 25 to 30 lb./A. Select a higher 

rate if you are seeding in spring or late in 

your window, or into a weedy or sloped field. 

Irrigation will help germination, but cultivation is 

likely to bury seeds too deeply. 

Plant hairy vetch 15 to 45 days before killing 

frost for winter annual management; in early 

spring for summer growth; and in July for fall 

incorporation or a winter-killed mulch. 

Hairy vetch has a relatively high P and K 

requirement and,like all legumes,needs sufficient 

sulfur and prefers a pH between 6.0 and 7.0. 

However,it can survive through a broad pH range 

of 5.6 to 7.5 (91). 

An Illinois farmer successfully no-tills hairy 

vetch in late August at 22 lb./A into closely 

mowed stands of fescue on former Conservation 

Reserve Program land (348). Using a herbicide to 

kill the fescue is cheaper—$8 to $10 to spray for 

growers owning their equipment vs. $10 to $12 

to mow—but it must be done about a month later 

when the grass is actively growing for the chemical 

to be effective (267). Vetch also can be notilled 

into soybean or corn stubble (32, 60). 

Farmers in the Northeast’s warmer areas plant 

vetch by mid-September to net 100 lb. N/A by 

mid-May. Sown mid-August, an oats/hairy vetch 

mix can provide heavy residue (138). 

Rye/hairy vetch mixtures mingle and moderate 

the effects of each crop. The result is a “hybrid” 

cover crop that takes up and holds some excess 

soil nitrate,fixes N,stops erosion,smothers weeds 

in spring and on into summer if not incorporated, 

contributes a moderate amount of N over a longer 

period than vetch alone,and offsets the N limiting 

effects of rye.The rye acts as a trellis, making the 

climbing vetch easier to mow and increasing its 

exposure to the sun (61, 63, 64, 310). 

In a vetch/rye mixture, an appropriate seeding 

rate for corn production in the mid-Atlantic 

region is 19 lb. hairy vetch with 42 lb. rye/A (61). 

A mix of 20 to 25 lb. hairy vetch and 70 lb. rye/A 

works in a variety of conditions (302),while some 

farmers report success with only 40 lb. rye/A. 

Overseeding (40 lb./A) at leaf-yellowing into 

soybeans can work if adequate rainfall and soil 

moisture are available prior to the onset of freezing 

weather. Overseeding into ripening corn (40 

lb./A) or seeding at layby has not worked as 

consistently. Late overseeding into vegetables is 


possible, but remember that hairy vetch will not 

stand heavy traffic (302). 

Killing 

Your mode of killing hairy vetch and managing 

residue will depend on which of its benefits are 

most important to you. Incorporation of hairy 

vetch vegetation favors first-year N contribution, 

but takes significant energy and labor. Keeping 

vetch residue on the surface favors weed suppression, 

moisture retention, and insect habitat, 

but may reduce N contribution. 

In spring, hairy vetch continues to add N 

through its “seed set” stage after blooming. 

Biomass and N increase until maturity, giving 

either greater benefit or a dilemma,depending on 

your ability to deal with vines that become more 

sprawling and matted as they mature. 

Climate influences the results of hairy vetch 

residue management. In the hot and humid conditions 

of the Southeast, no-till hairy vetch 

residue appears to contribute significant N without 

incorporation. Findings elsewhere (272) indicate 

that farmers in the cooler and drier areas of 

the western Corn Belt need to manage hairy 

vetch with mowing and tillage to achieve peak N 

benefits by preventing N volatilization (loss into 

the atmosphere). 

Mulch-retaining options include strip-tilling or 

strip chemical desiccation (leaving vetch untreated 

between the strips), mechanical killing (rotary 

mowing, flailing, cutting, sub-soil shearing with an 

undercutter, or chopping/flattening with a rolling 

stalk chopper) or broadcast herbicide application. 

No-till corn into killed vetch.The best time for 

no-till corn planting into hairy vetch varies with 

local rainfall patterns, soil type, desired N contribution, 

season length and vetch maturity. 

In southern Illinois, hairy vetch no-tilled 

into fescue provided 40 to 180 lb. N/A over 15 

years for one researcher/farmer. He used herbicide 

to kill the vetch about two weeks before the 

area’s traditional mid-May corn planting date. 

The 14-day interval was critical to rid the field of 

prairie voles, present due to the field’s thick 

fescue thatch. 

He kills the vetch when it is in its pre-bloom or 

bloom stage, nearing its peak N-accumulation 

capacity. Further delay would risk loss of soil 

moisture in the dry period customary there in 

early June (267). When the no-tilled vetch was left 

to grow one season until seed set, it produced 6 

tons of dry matter and contributed a potentially 

polluting 385 lb. N/A (348).This high dose of N 

must be managed carefully during the next year 

to prevent leaching or surface runoff of nitrates. 

A series of trials in Maryland showed a different 

mix of conditions. Corn planting in late-April is 

common there, but early killing of vetch to plant 

corn then had the surprising effect of decreasing 

soil moisture and corn yield, as well as predictably 

lowering N contribution. The earlier-planted corn 

had less moisture-conserving residue. Late April or 

early May kill dates, with corn no-tilled 10 days 

later, consistently resulted in higher corn yields 

than earlier kill dates (62, 63, 64). With hairy vetch 

and a vetch/rye mixture, summer soil water conservation 

by the cover crop residue had a greater 

impact than spring moisture depletion by the 

growing cover crop in determining corn yield (64). 

Results in the same trials,which also included a 

pure rye cover, demonstrated the management 

flexibility of a legume/grain mix. Early killed rye 

protects the soil as it conserves water and N, 

while vetch killed late can meet a large part of the 

N requirement for corn. The vetch/rye mixture 

can conserve N and soil moisture while fixing N 

for the subsequent crop.The vetch and vetch/rye 

mixture accumulated N at 130 to 180 lb./A.The 

mixture contained as much N—or more—than 

vetch alone (63). 

In an Ohio trial, corn no-tilled into hairy vetch 

at mid-bloom in May received better early season 

weed control from vetch mulch than corn seeded 

into vetch killed earlier. The late planting date 

decreased yield,however (145,289),requiring calculation 

to determine if lower costs for tillage, 

weed control, and N outweigh the yield loss. 

Once vetch starts to bloom, it is easily killed by 

any mechanical treatment (52). To mow-kill for 

mulch, rye grown with hairy vetch improves cutting 

by holding the vetch off the ground to allow 

more complete severing of stems from roots. Rye 

HAIRY VETCH 115

also increases the density of residue covering the 

vetch stubble to prevent regrowth. 

Much quicker and more energy-efficient than 

mowing is use of a modified Buffalo rolling stalk 

chopper, an implement designed to shatter standing 

corn stubble. The chopper’s rolling blades 

break over, crimp and cut crop stems at ground 

level, and handle thick residue of hairy vetch or 

foxtail millet at 8 to 10 mph (131). 

No-till vegetable transplanting. Vetch that is 

suppressed or killed without disturbing the soil 

maintains moisture well for transplanted vegetables. 

No-till innovator Steve Groff of Lancaster 

County, Pa., uses the rolling stalk chopper to create 

a killed organic mulch. His favorite mix is 25 

lb. hairy vetch, 30 lb. rye and 10 lb. crimson 

clover/A (132). 

No-till, delayed kill. Jeff Moyer of the Rodale 

Institute in Kutztown, Pa., no-tills corn into standing 

hairy vetch in late May or early June, waits 

several more days, then flail-chops the vetch 

before corn emergence. This method allows the 

vetch to produce maximum N and is late enough 

to allow soil warming even with the vetch in 

place (230). 

Also useful in killing hairy vetch on raised beds 

for vegetables and cotton is the improved prototype 

of an undercutter that 

leaves severed residue virtually 

undisturbed on the surface 

(70). The undercutter 

tool includes a flat roller 

attachment, which, by itself, 

usually provides only partial 

suppression unless used 

after flowering. 

Herbicides used to kill hairy vetch include 

glyphosate (only somewhat effective), paraquat, 

2,4-D, dicamba and triazines including atrazine, 

cyanazine and metribuzin.Vetch will die in three 

to 30 days (338), depending on the material used 

and crop conditions. 

Vetch incorporation. As a rule, to gauge the 

optimum hairy vetch kill date, credit vetch with 

adding two to three pounds of N per acre per 

Winter hardy through the 

warmer parts of Zone 4, few 

legumes can rival hairy 

vetch’s N contributions. 

sunny day after full spring growth begins. Usually, 

N contribution by early bloom (10-25 percent) 

stage warrants killing the legume, rather than 

accepting yield loss due to late planting to get 

marginally more N at seed set or natural dry down 

after seed set. 

Cutting hairy vetch close to the ground at full 

bloom stage usually will kill it. However, waiting 

this long means it will have maximum top 

growth,and the tangled mass of mature vetch can 

overwhelm many smaller mowers or disks. Flail 

mowing before tillage helps,but that is a time- and 

horsepower-intensive process. Sickle-bar mowers 

should only be used when the vetch is well supported 

by a cereal companion crop and the material 

is dry (351). 

Heavy disk harrows, rotovators and power 

spaders can incorporate heavy, unmowed vetch 

stands. A moldboard plow can turn under large 

amounts of mowed vetch. Chisel plows and 

lighter disks can handle vetch killed earlier with 

herbicides. 

Harvesting seed. Plant hairy vetch with grains if 

you intend to harvest the vetch for seed. Use a 

moderate seeding rate of 10-20 lb./A to keep the 

stand from getting too rank (132). Vetch seedpods 

will grow above the twining vetch vines and 

use the grain as a trellis, allowing you to run the 

cutter bar higher to reduce 

plugging of the combine. 

Direct combine at midbloom 

to minimize shattering, 

or swath up to a week 

later. Seed is viable for at 

least five years (302). 

If you want to save dollars 

by growing your own seed, be aware that the 

mature pods shatter easily, increasing the risk of 

volunteer weeds. To keep vetch with its nurse 

crop, harvest vetch with a winter cereal and keep 

seed co-mingled for planting. Check the mix carefully 

for weed seeds. 


• About 10 to 20 percent of vetch seed is “hard” 

seed that lays ungerminated in the soil for one or 

more seasons. This can cause a weed problem, 


especially in winter grains. With wheat, you can 

use 2,4-D for control. After a corn crop that can 

utilize the vetch-produced N, you could establish 

a hay or pasture crop for several years. 

• Don’t plant hairy vetch with a winter grain if 

you want to harvest grain for feed or sale. 

Production is difficult because vetch vines will 

pull down all but the strongest stalks. Grain contamination 

also is likely if the vetch goes to seed 

before grain harvest.Vetch seed is about the same 

size as wheat and barley kernels, making it hard 

and expensive to separate during seed cleaning 

(302). Grain price can be markedly reduced by 

only a few vetch seeds per bushel (82). 

• A severe freeze with temperatures less than 5 

F may kill hairy vetch if there is no snow cover, 

reducing or eliminating the stand and most of its 

N value. If winterkill is possible 

in your area, planting vetch with 

a hardy grain such as rye ensures 

spring soil protection. 


In legume comparison trials, 

hairy vetch usually hosts numerous small insects 

and soil organisms (162). Many are beneficial to 

crop production, (see below) but others are 

pests. Soybean cyst nematode (Heterodera 

glycines) and root-knot nematode (Meliodogyne 

spp.) sometimes increase under hairy vetch. If 

you suspect that a field has nematodes, carefully 

sample the soil after hairy vetch.If the pests reach 

an economic threshold, plant nematode-resistant 

crops and consider using another cover crop. 

Other pests include cutworms (302) and 

southern corn rootworm (47), which can be 

problems in no-till corn; tarnished plant bug— 

noted in coastal Massachusetts (38)—which readily 

disperses to other crops; and two-spotted 

spider mites in Oregon pear orchards (107). 

Leaving unmowed remnant strips can lessen 

movement of disruptive pests while still allowing 

you to kill most of the cover crop (38). 

Prominent among predator beneficials associated 

with hairy vetch are lady beetles,seven-spotted 

ladybeetles (38) and bigeyed bugs (Geocaris 

spp.). Vetch harbors pea aphids (Acyrthosiphon 

pisum) and blue alfalfa aphids (Acyrthosiphon 

kondoi) that do not attack pecans but provide a 

food source for aphid-eating insects that can disperse 

into pecans. (40). Similarly, hairy vetch blossoms 

harbor flower thrips (Frankliniella spp.), 

which in turn attract important thrip predators 

such as insidious flower bugs (Orius insidiosus) 

and minute pirate bugs (Orius tristicolor). 

Two insects may reduce hairy vetch seed yield 

in heavy infestations: the vetch weevil or vetch 

bruchid.Rotate crops to alleviate buildup of these 

pests (302). 

CROP SYSTEMS 

Mix hairy vetch with 

cereal grains to reduce 

the risk of N leaching. 

Killed hairy vetch creates a short-term but effective 

spring/summer mulch, especially for transplants. 

The mulch retains moisture, allowing 

plants to use mineralized nutrients 

better than unmulched 

fields. The management challenge 

is that the mulch also lowers 

soil temperature, which may 

delay early season growth (302). 

One option is to capitalize on 

high quality, low-cost tomatoes that capture the 

late-season market premiums. See Vetch Beats 

Plastic (p. 118). 

How you kill hairy vetch influences its ability 

to suppress weeds.Durability and effectiveness as 

a light-blocking mulch are highest where the 

stalks are left whole. Hairy vetch severed at the 

roots or sickle-bar mowed last longer and blocks 

more light than flailed vetch, preventing more 

weed seeds from germinating (70, 340). 

While there is evidence that hairy vetch 

exudes weak natural herbicides that may inhibit 

development of small onion, carrot and tomato 

seedlings (26), these compounds do not affect 

transplants (132). 

Southern farmers can use an overwintering 

hairy vetch crop in continuous no-till cotton. 

Vetch mixed with rye has provided similar or 

even increased yields compared with systems that 

Note: An unmown rye/hairy vetch mix sustained 

a population of aphid-eating predators that was 

six times that of the unmowed volunteer weeds 

and 87 times that of mown grass and weeds (39). 

HAIRY VETCH 117

Vetch Beats Plastic 

BELTSVILLE, Md.—Killed cover crop mulches 

can deliver multiple benefits for no-till 

vegetable crops.The system can provide its 

own N, quell erosion and leaching, and 

displace herbicides. It’s also more profitable 

than conventional commercial production 

using black plastic mulch. A budget analysis 

showed it also should be the first choice of 

“risk averse” farmers.These are individuals 

who prefer certain although more modest 

profit over higher average profit that is less 

certain (178). 

The key to the economic certainty of a 

successful hairy vetch planting is its low 

cost—about $80/A for seeding and mowing— 

compared with the black plastic at about $750 

for plastic, installation and removal. 

From refining his own research and on-farm 

tests in the mid-Atlantic region for several 

years, USDA’s Aref Abdul-Baki of the ARS 

Beltsville (Md.) Agricultural Research Center, 

outlines his approach: 

• Prepare beds—just as you would for planting 

tomatoes—at your prime time to seed hairy 

vetch. 

• Drill hairy vetch at 40 lb./A, and expect 

about 4 inches of topgrowth before 

dormancy, which stretches from mid- 

December to mid-March in Maryland. 

• After two months’ spring growth, flail mow 

or use other mechanical means to suppress 

the hairy vetch. Be ready to remow or use 

herbicides to clean up trouble spots where 

hairy vetch regrows or weeds appear. 

• Transplant seedlings using a minimum tillage 

planter able to cut through the mulch and 

firm soil around the plants. 

The hairy vetch mulch suppresses early 

season weeds. It improves tomato health by 

preventing soil splashing onto the plants, and 

keeps tomatoes from soil contact, improving 

quality. Hairy vetch-mulched plants may need 

more water. Their growth is more vigorous 

and may yield up to 20 percent more than 

those on plastic. Completing harvest by mid- 

September allows the field to be immediately 

reseeded to hairy vetch.Waiting for vetch to 

bloom in spring before killing it and the tight 

fall turnaround may make this system less 

useful in areas with a shorter growing season 

than this Zone 7, mid-Atlantic site. 

Abdul-Baki rotates season-long cash crops of 

tomatoes, peppers and cantaloupe through the 

same plot between fall hairy vetch seedings. 

He shallow plows the third year after 

cantaloupe harvest and seeds hairy vetch for 

flat-field crops of sweet corn or snap beans 

the following summer. 

He suggests seeding rye with the vetch 

(40 lb./A each) for greater biomass and longerlasting 

mulch. Adding 10-12 lb./A of crimson 

clover will aid in weed suppression and N 

value. Rolling the covers before planting 

provides longer-lasting residue than does 

mowing them. Some weeds, particularly 

perennial or winter annual weeds, can still 

escape this mixture, and may require 

additional management (2). 

include conventional tillage, winter fallow weed 

cover and up to 60 pounds of N fertilizer per acre. 

Typically, the cover crops are no-till drilled after 

shredding cotton stalks in late October. Covers 

are spray killed in mid-April ahead of cotton planting 

in May. With the relatively late fall planting, 

hairy vetch delivers only part of its potential N in 

this system. It adds cost, but supplies erosion 

control and long-term soil improvement (21). 

Cotton yields following incorporated hairy 

vetch were perennial winners for 35 years at a 

northwestern Louisiana USDA site. Soil organic 

matter improvement and erosion control were 

additional benefits (222). 

Other Options 

Spring sowing is possible, but less desirable than 

fall establishment because it yields significantly 


less biomass than overwintering stands. Hot 

weather causes plants to languish. 

Hairy vetch makes only fair grazing—livestock 

do not relish it. Heavy feeding for 20 days in hairy 

vetch pasture resulted in death for eight of 33 cattle 

in one trial in South America (351). 


Hairy vetch is better adapted to sandy soils than 

crimson clover (285), but is less heat-tolerant than 

LANA woolypod vetch.See Woolypod Vetch (p.151). 

SEED 

Cultivars. MADISON—developed in Nebraska— 

tolerates cold better than other varieties. Hairy 

vetches produced in Oregon and California tend 

to be heat tolerant. This has resulted in two 

apparent types,both usually sold as “common”or 

“variety not stated” (VNS). One has noticeably 

hairy, bluish-green foliage with bluish flowers 

and is more cold-tolerant. The other type has 

smoother, deep-green foliage and pink to violet 

flowers. 

A closely related species—LANA woolypod 

vetch (Vicia dasycarpa)—was developed in 

Oregon and is less cold tolerant than Vicia villosa. 

Trials in southeastern Pennsylvania with 

many accessions of hairy vetch showed bigflower 

vetch (Vicia grandiflora, cv WOODFORD) was the 

only vetch species hardier than hairy vetch. EARLY 

COVER hairy vetch is said to be 10 days earlier than 

regular common seed (337). 


MEDICS 

Medicago spp. 

Also called: black medic, bur medic, 

burclover 

Type: Winter annual or summer 

annual legume 

Roles: N source, soil quality builder, 

weed suppressor, erosion fighter 

Mix with: Other medics; clovers 

and grasses; small grains 



annual medics 

perennial medics 

(dryland) 

annual medics 

marginal utility 

Once established, few other legumes outperform 

medics in soil-saving,soil-building 

and forage when summer rainfall is less 

than 15 inches.They serve well in seasonally dry 

areas from mild California to the harsh Northern 

Plains. With more rainfall, however, they can produce 

almost as much biomass and N as clovers. 

Medics are self-reseeding with abundant “hard 

seed”that can take several years to germinate. This 

makes medics ideal for long rotations of forages 

and cash crops in the Northern Plains and in cover 

crop mixtures in the drier areas of California. 

MEDICS 119

Annual medics include 35 known species 

that vary widely in plant habit, maturity date and 

cold tolerance. Most upright varieties resemble 

alfalfa in their seeding year with a single stalk and 

short taproot.Medics can produce more than 100 

lb. N/A in the Midwest under favorable conditions,but 

have the potential for 200 lb.N/A where 

the plants grow over winter. They germinate 

and grow quickly when soil moisture is adequate, 

forming a thick ground cover that holds soil in 

place. The more prostrate species of annual 

medic provide better ground cover. 

Significant annual types include: bur medic (M. 

polymorpha), which grows up to 14 inches tall, is 

semi-erect or prostrate, hairless, and offers great 

seed production and N-fixing ability; barrel medic 

(M. truncatula), about 16 inches tall, with many 

mid-season cultivars; and 

snail medic (M. scutellata), 

which is a good biomass and 

N producer. 

Southern spotted bur 

medic is a native M. polymorpha 

cultivar with more winterhardiness 

than most of the current bur medics, 

which are imported from Australia. See Southern 

Bur Medic Offers Reseeding Persistence (p. 122). 

Naturalized bur medic seed is traded locally in 


Annual medics broadcast in spring over wheat 

stubble in Michigan reduced weed number and 

growth of spring annual weeds prior to no-till 

corn planting the following spring.Spring-planted 

annual medics produced dry matter yields similar 

to or greater than alfalfa by July (308). 

GEORGE black medic (M. lupulina) is usually 

called a perennial. It can improve soil, reduce diseases, 

save moisture and boost grain protein 

when grown in rotations with grains in the 

Northern Plains. GEORGE is the most widely used 

cultivar in dryland areas of the Northern Plains. 

Black medic produces abundant seed. Up to 96 

percent of it is hard seed, much of it so hard seeded 

that it won’t germinate for two years. Secondyear 

growth may be modest, but coverage 

improves in years three and four after the initial 

seeding if competition is not excessive (351) and 

grazing management is timely. 

BENEFITS 

Hard-seeded medics are 

ideal for reseeding systems 

in orchards and vineyards. 

Good N on low moisture. In dryland areas, 

most legumes offer a choice between N production 

and excessive water use. Medics earn a place 

in dryland crop rotations because they provide N 

while conserving moisture comparable to bareground 

fallow (313, 347). Fallow is the intentional 

resting of soil for a season so it will build up 

moisture and gain fertility by biological breakdown 

of organic matter. Black medic increased 

spring wheat yield by about 92 percent compared 

with spring wheat following fallow, and also 

appreciably raised the grain protein level (312). 

April soil N value after black medic in one 

Montana test was 117 lb./A, about 2.5 times the 

fallow N level and the best of six cultivars tested, 

all of which used less water 

than the fallow treatment 

(311). GEORGE grows in a 

prostrate to ascending fashion 

and overwinters well 

with snow cover in the 

Northern Plains. 

Great N from more water. Under normal dryland 

conditions,medics usually produce about 1 T 

dry matter/A, depending on available soil moisture 

and fertility. When moisture is abundant, 

medics can reach their full potential of 3 T/A of 

3.5 to 4 percent plant-tissue nitrogen, contributing 

more than 200 lb. N/A (157, 351). 

Fight weeds. Quick spring regrowth suppresses 

early weeds. Fall weeds are controlled by medic 

regrowth after harvest, whether the medic stand 

is overseeded or interplanted with the grain, or 

the grain is seeded into an established medic 

stand. In California orchards and vineyards where 

winters are rainy instead of frigid, medics mixed 

with other grasses and legumes provide a continuous 

cover that crowds out weeds. In those situations, 

medics help reduce weed seed production 

for the long-term. 

Boost organic matter. Good stands of medics in 

well drained soil can contribute sufficient residue 

to build soil organic matter levels. One Indiana 


Jess Counts on GEORGE for N and Organic Matter 

STANFORD, Mon. — Jess Alger can count on spring wheat crop, the other he planted into a 

13 inches of rainfall or less on his central six-year-old stand of GEORGE medic.After a year 

Montana farm, occasional hail damage, killing of canola and a green fallow year of just selfseeded 

medic, Alger added to the seed bank 

frosts after June 10 now and then, too few 

solar units to raise safflower or millet, some with a no-till planting of GEORGE with a nurse 

bone-chilling winters without snow cover— crop of Austrian winter peas in ’96. 

and George.That’s GEORGE black medic. 

The ’97 medic/wheat interplant yielded 

Tests from 1997 showed he got 87 lb. N/A 29 bushels per acre—six bushels less than the 

and 4.3 percent organic matter in a clay loam other field. But the interplanted grain tested 

field. He initially seeded the medic on 10-inch at 15 percent protein, a full percentage point 

row spacings with barley in 1990 at 10 lb./A, higher. Those are high yields for Alger’s area, 

his standard rate and seeding method. He 

partly due to timely summer rain.“The yield 

grazed the medic early in the second year, then drop with medic was mostly a weed problem 

let it go to seed. In Year 3, he sprayed it with with Persian darnel,”Alger explains. He’ll graze 

glyphosate in order to establish a sorghumsudangrass 

hybrid as emergency forage on May darnel, an annual, doesn’t go to seed. 

the field closely in ’98 to make sure the 

15. He had several inches of growth when frost To plant winter wheat into the seven-yearold 

medic sward in fall ’97, he used three 

hit about June 10 and killed the tender grass. 

The medic came on strong. He let it mature passes with a chisel plow and sweeps to 

to its full 12 inches to harvest it for seed.“It kill and partially incorporate the legume. He 

was already laying over, but the pickup guards planted wheat with a conventional planter in 

on my combine helped to gather in about half early October. He hopes someday to use a 

the seed.”The other half pumped up the seed no-till planter so he can leave most of the 

bank for years ahead. 

medic in place, bury less seed and allow 

He did a comparison in ‘97 with side-by-side GEORGE to rest more securely in his field. 

fields of spring wheat. One followed a ’96 

test reported a yield of more than 9,000 lb. dry 

matter/A from a spring-sown barrel medic (129). 

Reduce soil erosion. Medics can survive in summer 

drought-prone areas where few other cultivated 

forage legumes would, thanks to their 

hard-seeded tendency and drought tolerance. 

Low, dense vegetation breaks raindrop impact 

while roots may penetrate 5 feet deep to hold soil 

in place. 

Tolerate regular mowing. Medics can be 

grazed or mowed at intervals with no ill effects. 

They should be mowed regularly to a height of 3 

to 5 inches during the growing season for best 

seed set and weed suppression. To increase the 

soil seed bank, rest medic from blooming to seed 

maturation, then resume clipping or grazing 

(227, 351, 357). 

Provide good grazing. Green plants, dry plants 

and burs of bur medic provide good forage, but 

solid stands can cause bloat in cattle (351). The 

burs are concentrated nutrition for winter forage, 

but lower the value of fleece when they become 

embedded in wool. Annual medics overseeded 

into row crops or vegetables can be grazed in fall 

after cash crop harvest (217). 

Reseeding. Black medic has a high percentage of 

hard seed.Up to 90 percent has an outer shell that 

resists the softening by water and soil chemicals 

that triggers germination (228).Scarified seed will 

achieve 95 percent germination, and 10-year old 

MEDICS 121

Southern Spotted Bur Medic Offers Reseeding Persistence 

While annual medics, in general, are hard reseeded in a Louisiana no-till cotton field 

seeded, they usually cannot tolerate winters for more than 10 years without special 

north of the Gulf South. Southern spotted management to maintain it (77). 

bur medic (Medicago arabica) shows 

Research in the Southeast showed that if 

promise as a winter legume that can reseed Southern spotted bur medic begins blooming 

for several years from a single seed crop in March 23, it would form viable seed by May 2, 

Hardiness Zone 7 of the Southeast. 

and reach maximum seed formation by May 

Once as widely grown as hairy vetch in the 12. By allowing the cover crop to grow until 

mid-South region of the U.S., bur medic 

40 to 50 days after first bloom and managing 

persists in non-cropland areas because it is the cropping system without tillage that 

well adapted to the region (265, 266). A local would bury burclover seeds too deeply, 

accession collected in northern Mississippi Southern spotted burclover should 

exhibits better cold hardiness and insect 

successfully reseed for several years. 

resistance than commercially available 

Native medic seed is being increased in 

(Australian) annual medics. 

cooperation with the USDA-Natural Resources 

In a replicated cold-hardiness trial spanning Conservation Service’s Jamie Whitten Plant 

several states, spotted bur medic flowered in Materials Center, Coffeeville, Miss., for 

mid-March, about two weeks after SERENA, possible accelerated release to seed growers 

CIRCLE VALLEY, or SANTIAGO burclover, but two as a “source-identified” cover crop. As of late 

weeks before TIBBEE crimson clover.The bur 1997, there were no commercial seed sources 

medic flowered over a longer period than for Southern spotted bur medic seed. 

crimson, matured seed slightly sooner than 

Insect pests such as clover leaf weevil 

TIBBEE but generally did not produce as much (Hypera punctata Fabricius) and the 

biomass. 

alfalfa weevil (Hypera postica Gyllenhal) 

The big advantage of spotted bur medic preferentially attack medics over other 

over crimson clover was its ability to reseed winter legume cover crops in the Southeast, 

for several years from a single seed crop. In and could jeopardize seed production.These 

studies in several states, the native medic insects are easily controlled with pyrethroid 

successfully reseeded for at least two years insecticides when weevils are in their second 

when growth was terminated two weeks after instar growth stage.While not usually needed 

TIBBEE bloomed. Only balansa clover (see Upand-Coming 

Cover Crops, p. 158) reseeded icides may be warranted in the seeding year 

for single-season cover crop benefits, insect- 

as well as spotted burclover (79). The bur to ensure a reseeding crop for years to come. 

medic cultivar CIRCLE VALLEY successfully 

raw seed may still be 50 percent viable (351). Bur 

medic seed in the intact bur remains viable for a 

longer time than hulled seed (91). 

Their status as a resilient,reseeding forage makes 

medics the basis for the “ley system” developed in 

dry areas of Australia. Medics or subterranean 

clover pastured for several years on Australian drylands 

help to store moisture and build up soil productivity 

for a year of small grain production before 

being returned to pasture. This use requires livestock 

for maximum economic benefit. GEORGE 

black medic is prostrate,allowing other grasses and 

forbs to become the overstory for grazing.It is wellsuited 

to cold winter areas of Hardiness Zone 4, 

where it can stay green much of the winter (3). 

Quick starting. Black medic can germinate within 

three days of planting (228). About 45 days 


after mid-April planting in southern Illinois, two 

annual medics were 20 inches tall and blooming. 

In the upper Midwest, snail and bur medics 

achieve peak biomass about 60 days after planting. 

An early August seeding of the annuals in 

southern Illinois germinated well, stopped growing 

during a hot spell, then restarted. Growth was 

similar to the spring-planted plots by Sept. 29 

when frost hit.The plants stayed green until the 

temperature dipped to the upper teens (157). 

Widely acclimated. Species and cultivars vary 

by up to seven weeks in their estimated length of 

time to flowering. Be sure to select a species to 

fit your weather and crop rotation. 

MANAGEMENT 

Establishment 

Annual medics offer great potential as a substitute 

for fallow in dry northern regions of the U.S. with 

longer day length. Annual medics need to fix as 

much N as winter peas or lentils and have a competitive 

establishment cost per acre to be as valuable 

as these better-known legume green 

manures (316). 

Medics are widely adapted to soils that are reasonably 

fertile, but not distinctly acid or alkaline. 

Excessive field moisture early in the season can 

significantly reduce medic stands (308). Acid-tolerant 

rhizobial strains may help some cool-season 

medics, especially barrel medic, to grow on sites 

that otherwise would be inhospitable (351). 

To reduce economic risk in fields where you’ve 

never grown medic, sow a mixture of medics 

with variable seed size and maturation dates. In 

dry areas of California, medic monocultures are 

planted at a rate of 2 to 6 lb./A,while the rate with 

grasses or clovers is 6 to 12 lb./A (351). 

Establishment options vary depending on 

climate and crop system: 

• Early spring—clear seed. Drill 1 /4 to 1 /2 inch 

deep (using a double-disk or hoe-type drill) into a 

firm seed bed as you would for alfalfa. Rolling is 

recommended before or after seeding to improve 

seed-soil contact and moisture in the seed zone. 

Seeding rate is 8 to 10 lb./A for black medic,12 to 

20 lb./A for larger-seeded (snail, gamma and bur) 

annual medics. In the arid Northern Plains, fall 

BLACK MEDIC (Medicago lupulina) 

germination and winter survival are dependable, 

although spring planting also has worked. 

• Spring grain nurse crop. Barley, oats, 

spring wheat and flax can serve as nurse crops for 

medic, greatly reducing weed pressure in the 

seeding year. The drawback is that nurse crops 

will reduce first-year seed production if you are 

trying to establish a black medic seed bank. To 

increase the soil seed reserve for a long-term 

black medic stand (germinating from hard seed), 

allow the medic to blossom, mature and reseed 

during its second year. 

• Corn overseed. SANTIAGO bur medic was 

successfully established in no-till corn three to six 

weeks after corn planting, but biomass and weed 

suppression were negligible during a two-year 

trial in Michigan. Medic seed was broadcast, then 

lightly incorporated as dicamba herbicide was 

sprayed over the corn to control weeds. Because 

of variable and generally disappointing results 

throughout the upper Midwest, current medic 

species and cultivars are not recommended for 

underseeding in corn (308). 

Where medic and corn work together, such as 

California, maximize medic survival during the 

corn canopy period by seeding early (when corn 

Elayne Sears 

MEDICS 123

is eight to 16 inches tall) and heavy (15 to 20 

lb./A) to build up medic root reserves (31, 351). 

• After wheat harvest. MOGUL barrel medic 

seeded after wheat harvest produced 119 lb. N/A 

in southern Michigan, more than double the N 

production of red clover seeded at the same time 

(308). Planted even at mid-season in Montana, 

snail medic establishes well, smothers weeds, 

builds up N, then winterkills for a soil-holding 

organic mulch. 

• Autumn seeding.Where winters are rainy in 

California, medics are planted in October as winter 

annuals (358). Plant about the same time as 

crimson clover in the Southeast, Zones 7 and 8. 

Killing 

Medics are easy to control by light tillage or 

herbicides. They reseed up to three times per 

summer,dying back naturally each time.Medics in 

the vegetative stage do not tolerate field traffic. 


Black medic>small grain rotations developed in 

Montana count on successful self-reseeding of 

medic stands for grazing by sheep or cattle. A 

month of summer grazing improves the economics 

of rotation by supplying forage for about one 

animal unit per acre. In 

this system, established, 

self-reseeding black medic 

plowed down as green 

manure in alternate years 

improved spring wheat 

yield by about 50 percent 

compared to fallow (313). 

Black medic is a dual-use legume in this adapted 

“ley” system. Livestock graze the legume in the 

“medic years” when the cover crop accumulates 

biomass and contributes N to the soil. Cash crops 

can be no-tilled into the medic,or the legume can 

be incorporated. 

A well-established black medic stand can 

reduce costs compared with annual crops by 

coming back for many years. However, without 

the livestock grazing benefit to supply additional 

utilization, water-efficient legumes such as lentils 

and Austrian winter peas will probably be more 

Medics earn a place in dryland 

rotations because they provide 

N while conserving moisture. 

effective N sources. Further, the long-lived seed 

bank that black medic establishes may be undesirable 

for some cash crop rotations in areas of 

higher rainfall (316). 

Use of medics in the upper Midwest is still in 

the exploratory stage.In a series of trials in Ohio, 

Michigan, Wisconsin and Minnesota, medic did 

not provide enough weed control or N to justify 

its use under current cash grain prices, even 

when premiums for pesticide-free corn were 

evaluated (308). One Michigan farmer’s situation 

is fairly typical. He established annual medic at 

10 lb./A when his ridge-tilled corn was about 

knee-high. The legume germinated, but didn’t 

grow well or provide weed suppression until 

after corn dry-down in mid-September. The 

medic put on about 10 inches of growth before 

winterkilling, enough for effective winter erosion 

protection (157). 

Soybeans offer a better economic window for 

medics to work. The expected yield loss is relatively 

smaller (6 bu./A) and higher pesticide-free 

premiums could make the system profitable,even 

with lower yield. In 1995, an economic analysis 

showed that a premium of 72 cents per bushel 

over a base price of $6.50 would have made 

medic a profitable weed-control option, without 

counting its soil-building 

value (308). 

Black medic and two 

annual medics produced 

50 to 150 lb. N/A when 

interplanted with standard 

and semi-dwarf barley in a 

Minnesota trial.Annual MOGUL produced the most 

biomass by fall, but also reduced barley yields. 

GEORGE was the least competitive and fixed 

55 to 120 lb. N/A. The taller barley was 

more competitive, indicating that taller small 

grain cultivars should be used to favor grain production 

over medic stand development (231). 

Midwestern farmers can overseed annual 

medic or a medic/grass mixture into wheat in 

very early spring for excellent early summer grazing. 

With timely moisture, you can get a hay cutting 

within nine to 10 weeks after germination, 

and some species will keep working to produce a 


second cutting. Regrowth comes from lateral 

stems, so don’t clip or graze lower than 4 or 5 

inches if you want regrowth. To avoid bloat, 

manage as you would alfalfa (157). 

Annual medics can achieve their full potential 

when planted after a short-season spring crop 

such as processing peas or lettuce. Wisconsin 

tests at six locations showed medic produced an 

average of 2. 2 T/A when sown in the late June or 

early July (327). Early planting in this window 

with a late frost could give both forage and N- 

bearing residue, protecting soil and adding spring 

fertility. Take steps to reduce weed pressure in 

solid seedings, especially in early July. 

In another Michigan comparison,winter canola 

(Brassica napus) yields were similar after a green 

manure comparison of two medics, berseem 

clover and NITRO annual alfalfa. All the covers 

were clear (sole-crop) seeded in early May after 

pre-plant incorporated herbicide 

treatment, and were 

plowed down 90 days later. 

Harvesting the medics at 60 

days as forage did not significantly 

lessen their green 

manure value (308). 

In the mid-Atlantic at the USDA Beltsville, Md., 

site, medics have been hard to establish by overseeding 

at vegetable planting or at final cultivation 

of sweet corn (338). 


Under water logged conditions for which they are 

ill-suited, annual medics are susceptible to diseases 

like Rhizoctonia, Phytophthora and 

Fusarium (217). 

Bur medic harbors abundant lygus bugs in 

spring. It also appears to be particularly prone to 

outbreaks of the two-spotted spider mite, a pest 

found in many West Coast orchards (351). 

Most medics tolerate low doses of the herbicide 

2-4,D-amine and glysophate.They are somewhat 

resistant to 2-4,DB (351). Other herbicides 

compatible with medics include EPTC, bromoxynil 

before medic emergence and bentazon 

and imidazolinone on medic seeded with imidazolinone-resistant 

corn (217). Glysophate, paraquat, 

2,4-D and dicamba kill medic effectively 

(25). One report says bur medic is very sensitive 

to 2,4-D. 

Pods and viable seeds develop without pollinators 

because most annual medics have no floral 

nectaries (91). 


With abundant moisture, 

medics can produce more 

than 200 lb. N/A. 

Snail medic produced about the same biomass 

and N as red clover when both legumes were 

spring sown with an oats nurse crop into a disked 

seedbed in Wisconsin. Yields averaged over one 

wet year and one dry year were about 1 T dry matter 

and 60 lb. N/A (308). 

Medics can establish and survive better than 

subterranean clover in times of low rainfall, and 

are more competitive with grasses. A short period 

of moisture will allow medic to germinate and 

send down its fast-growing 

taproot, while subclover 

needs more consistent moisture 

for its shallower, slower 

growing roots (351). Medics 

are more susceptible than 

subclover to seed production 

loss from closely mowing densely planted erect 

stalks. Bur and barrel medics are not as effective 

as subclover at absorbing phosphorus (351). 

Medics may survive where true clovers 

(Trifolium spp.) fail due to droughty conditions 

(351) if there is at least 12 in.of rain per year (234). 

Medics grow well in mixtures with grasses and 

clovers, but don’t perform well with red clover 

(351, 211). Once established, black medic handles 

frost better than crimson or red clover. 

GEORGE grows more slowly than yellow blossom 

sweetclover in spring of the second year, but 

it starts flowering earlier. It uses less water in the 

2- to 4-foot depth than sweetclover, soybeans or 

hairy vetch seeded at the same time (295). 

SEED 

Annual Medic Cultivars. Species and cultivars 

of annual medic vary significantly in their dry matter 

production, crude protein concentration and 

MEDICS 125

total N. Check with local or regional forage 

specialists for cultivar recommendations 

Bur medic (also called burclover) cultivars are 

the best known of the annual medics. They 

branch profusely at the base, and send out prostrate 

stems that grow more erect in dense stands 

(351). They grow quickly in response to fall 

California rains and fix from 55 to 90 lb.N/A,nearly 

as much as true clovers (236, 351). Most stands 

are volunteer and can be encouraged by proper 

grazing, cultivation or fertilization. 

Selected cultivars include SERENA (an early 

bloomer), and CIRCLE VALLEY, both of which have 

fair tolerance to Egyptian alfalfa weevil (357). 

SANTIAGO blooms later than SERENA. Early bur 

medics flower in about 62 days in California,ranging 

up to 96 days for mid-season cultivars (351). 

Naturalized and imported bur medic proved 

the best type of burclover for self-reseeding cover 

crops in several years of trials run 

from northern California into 

Mexico in the 1990s. While some 

of the naturalized strains have 

been self-reseeding for 30 years in 

some orchards, Extension specialists 

say the commercial cultivars 

may be preferable because they are widely available 

and better documented (58). 

Established bur medic tolerates shade as a common 

volunteer in the understories of California 

walnut orchards, which are heavily shaded from 

April through November. However, in Michigan 

trials over several years, SANTIAGO (a bur medic 

with no spines on its burs) failed to establish satisfactorily 

when it was overseeded into corn and 

soybeans at layby. Researchers suspect the crop 

canopy shaded the medic too soon after planting, 

and that earlier overseeding may have allowed the 

medic to establish (134). 

There are at least 10 cultivars of barrel medic. 

Dates of first flowering for barrel medics range 

from 80 to 105 days after germination, and seed 

count per pound ranges from 110,000 for 

HANNAFORD to 260,000 for SEPHI (351). A leading 

new cultivar, SEPHI, flowers about a week earlier 

Medics are easy to 

kill with light tillage 

or most herbicides. 

than JEMALONG, commonly used in California (200, 

351).SELPHI,a mid-season cultivar,has a more erect 

habit for better winter production, is adapted to 

high- and low-rainfall areas, yields more seed and 

biomass than others, has good tolerance to 

Egyptian alfalfa weevil and high tolerance to spotted 

alfalfa aphid and blue green aphid. It is susceptible 

to pea aphid. 

Snail medic (M. scutellata) is a prolific seed 

producer. Quick germination and maturity can 

lead to three crops (two reseedings) in a single 

season from a spring planting in the Midwest 

(308).MOGUL barrel medic grew the most biomass 

in a barley intercrop,compared with SANTIAGO bur 

medic and GEORGE black medic in a four-site 

Minnesota trial. It frequently reduced barley 

yields, particularly those of a semi-dwarf barley 

variety, but increased weed suppression and N 

and biomass production (231). 

In a Michigan test of forage 

legumes for emergency forage 

use, MOGUL barrel medic produced 

1.5 T dry matter/A compared 

to about 1 T/A for SAVA snail 

medic and SANTIAGO bur medic 

(M. polymorpha). Nitrogen production 

was 66 lb./A for MOGUL,46 for SAVA and 22 

for SANTIAGO.The seeding rate for SAVA medic is 29 

lb./A,more than twice the 13 lb./A recommended 

for clear seedings of MOGUL and SANTIAGO (308). 

In a California pasture comparison of three 

annual medics, JEMALONG barrel had the highest 

level of seed reserves in the soil after six years,but 

didn’t continue into the seventh year after the initial 

seeding. GAMMA medic (M. rugosa) had the 

highest first-year seed production but re-established 

poorly, apparently due to a low hard seed 

content. All the medics re-established better 

under permanent pasture than under any rotational 

system involving tillage (68, 351). 

Seed sources. Widely available in California; 

nationally through Kamprath, Peaceful Valley, 

Timeless and Wolf River. See Seed Suppliers 

(p. 166). 


RED CLOVER 

Trifolium pratense 

Also called: medium red clover 

(multi-cut, early blooming, June 

clover); mammoth clover (singlecut, 

late blooming, Michigan red) 

Type: short-lived perennial, biennial 

or winter annual legume 

Roles: N source, soil builder, weed 

suppressor, insectary crop, forage 

Mix with: small grains, corn, soybeans, 

vegetables, grass forages 

See charts, p. 47 to 53, for rankings 


spring seeded biennial 

winter annual 

Red clover is a dependable, low-cost, readily 

available workhorse that is winter hardy in 

much of the U.S. (Hardiness Zone 4 and 

warmer). Easily overseeded or frostseeded into 

standing crops, it creates loamy topsoil, adds a 

moderate amount of N, helps to suppress weeds 

and breaks up heavy soil. Its most common uses 

include forage,grazing,seed harvest,plowdown N 

and, in warmer areas, hay. It’s a great legume to 

frostseed or interseed with small grains where 

you can harvest grain as well as provide weed 

suppression and manage N. 

BENEFITS 

Crop fertility. As a cover crop, red clover is used 

primarily as a legume green manure killed ahead 

of corn or vegetable crops planted in early 

summer. Full-season, over-wintered red clover 

can produce 2 to 3 T dry matter/A and fix nitrogen 

at 70 to 150 lb. /A. 

Two years of testing in Wisconsin showed that 

conventionally planted corn following red clover 

yielded the same as corn supplied with 160 lb. 

N/A, with less risk of post-harvest N leaching. 

Further, monitoring of the corn and the soil 

showed that 50 percent of the cover crop N was 

released in the first month after incorporation, 

corresponding well with corn’s fertility demand. 

Post-harvest soil N levels in the clover plots were 

the same or less than the fertilized plots, and 

about the same as unfertilized plots (329). 

Widely adapted. While many other legumes can 

grow quicker, produce more biomass and fix 

more nitrogen, few are adapted to as many soil 

types and temperate climatic niches as red clover. 

As a rule, red clover grows well wherever corn 

grows well. It does best in cool conditions. 

In southern Canada and the northern U.S., and 

in the higher elevations of the Southeast and 

West, red clover grows as a biennial or short-lived 

perennial. At lower elevations in the Southeast, it 

grows as a winter annual, and at lower elevations 

in the West and Canada, it grows under irrigation 

as a biennial (91).It grows in any loam or clay soil, 

responding best to well-drained, fertile soils. 

Many economic uses. Red clover has been a 

popular,multi-use crop since European immigrant 

farmers brought it to North America in the 1500s. 

It remains an important crop thanks to its greater 

RED CLOVER 127

adaptability, lower seeding cost and easier establishment 

than alfalfa. It can produce up to 8,000 

lb. biomass/A (277). 

A red clover/small grain mix has been a traditional 

pairing that continues to be profitable. A 

rotation of corn and oats companion-seeded with 

red clover proved as profitable as continuous 

corn receiving 160 lb. N/A in a four-year 

Wisconsin study (328). Both had gross margins of 

about $166/A, with fertilizer nitrogen figured at 

$0.12/lb. as anhydrous ammonia. 

Red clover was the most profitable of five 

legumes under both seeding methods in the 

trial—sequentially planted after oats harvest or 

companion planted with oats in early spring. 

The companion seedings yielded 

nearly twice as much estimated fertilizer 

replacement value as the sequential 

seedings. The work showed 

that red clover holds great potential 

to reduce fertilizer N use for corn 

grown in rotation (329). 

Red clover sown as a companion 

with spring oats outperformed the other legumes, 

which suffered from insect damage, 

mechanical damage during oat harvest and slow 

subsequent regrowth. The short season proved 

inadequate for sequentially seeded legumes with 

the exception of hairy vetch, which was nearly as 

profitable as the red clover. 

The role of red clover’s N contribution in the 

rotation grew more significant in 1996 when N 

prices had risen 83 percent, even though clover 

seed price had also risen 40 percent from the original 

1989 calculations. A corn>soybean>wheat/ 

red clover sequence had a gross margin of $17/A 

more than continuous corn and nearly $10/A more 

than an oats>corn rotation in 1996 (326). 

Soil conditioner. Red clover is an excellent soil 

conditioner, with an extensive root system that 

permeates the topsoil. Its taproot may penetrate 

several feet. 

Attracts beneficial insects. Red clover earned a 

co-starring role with LOUISIANA S-1 white clover in 

pecan orchard recommendations from Oklahoma 

State University in 1996. Red clover attracts more 

Red clover can 

yield 2 to 3 tons 

of dry matter and 

70 to 150 lb. N/A 

beneficials than white clover,which features higher 

N fixation and greater flood tolerance than red 

clover (209). 

Two Types 

Two distinct types of red clover have evolved 

from the same species. Be sure you plant a cultivar 

with the regrowth option if you plan to make 

more than one green manure cutting, or to maintain 

the stand to prepare for a late-summer vegetable 

planting. 

Medium red clover. Medium red (some call it 

multi-cut) grows back quickly, and can be cut 

once late in the seeding year and twice the following 

year.For optimum N benefit 

and flexible cropping options from 

the planting (allowing it to overwinter 

as a soil-protecting mulch), 

you can use it for hay, grazing or 

seed throughout the second season. 

Seed may be priced the same 

as single-cut types (240), or it can 

be up to 25 percent more than single-cut. See 

Chart 3B: Planting (p. 51). 

Mammoth red clover produces as much N 

pound for pound and will produce significant biomass 

in a single first cutting,but does not produce 

as much biomass overall as medium red’s multiple 

cuttings over time. Use this “single-cut” red clover 

where a field will be all-clover just during the 

seeding year. Slow-growing mammoth doesn’t 

bloom the establishment year and regrows quite 

slowly after cutting, but can provide good biomass 

by the end of even one growing season. 

A single cutting of mammoth will give slightly 

more biomass—at a slightly lower cost—than a 

single cutting of medium red. Where multiple 

cuttings or groundcover are needed in the second 

season, medium red clover’s higher seed cost is 

easily justified (153). 

Some types of mammoth do better overseeded 

into wheat than into oats. ALTASWEDE (Canadian) 

mammoth is not as shade tolerant as MICHIGAN 

mammoth, but works well when seeded with 

oats. MICHIGAN mammoth shows the best vigor 

when frostseeded into wheat, but is not as 

productive as medium red (183). 


MANAGEMENT 


In spring in cool climates, red clover germinates 

in about seven days—quicker than many 

legumes—but seedlings develop slowly, similar to 

winter annual legumes. Traditionally it is drilled 

at 8 to 12 lb./A with spring-sown grains, using 

auxiliary or “grass seed”drill boxes.Cut back small 

grain seeding rates up to 50 percent from pure 

stand rates, if clover for forage is your main goal. 

Wisconsin researchers who have worked for several 

years to optimize returns from red clover/ 

oats interseedings say planting oats at 3 to 4 bu./A 

gives good stands of clover without sacrificing 

grain yield (326). 

Red clover’s tolerance of shade and its ability to 

germinate down to 41 F give it a remarkable range 

of establishment niches. 

It can be overseeded at 10 to 18 lb./A into: 

• Dormant winter grains before ground 

thaws. This “frostseeding”method relies on movement 

of the freeze-thaw cycle to work seed into 

sufficient seed-soil contact for germination. 

Michigan farmers frostseed red clover at 6 to 8 

lb./A (240). If the soil is level and firm, you can 

broadcast seed over snow cover on level terrain. 

You can seed the clover with urea if fertilizer 

application is uniform (183). Use just enough 

N fertilizer to support proven small-grain yields, 

because excess N application will hinder clover 

establishment. To reduce small grain competition 

with clover in early spring, graze or clip the small 

grain in early spring just before the stems begin to 

grow (91). Hoof impact from grazing also helps 

ensure seed-to-soil contact. 

• Summer annuals such as oats, barley, spelt 

or spring wheat before grain emergence. 

• Corn at layby. Wait until corn is 10 to 12 

inches tall, at the V-4 to V-6 growth stage. Clover 

sown earlier in favorable cooler conditions with 

more light may compete too much for water. 

Later, the clover will grow more slowly and not 

add substantial biomass until after corn harvest 

lets light enter (153). Dairy producers often 

broadcast red clover after corn silage harvest. 

• After wheat harvest. Red clover logged a 

fertilizer replacement value of 36 lb.N/A in a twoyear 

Michigan trial that used N isotopes to track 

nitrogen fixation. Red clover and three other 

legumes were no-till drilled into wheat stubble in 

August, then chemically killed by mid-May just 

ahead of no-till corn. Clover even in this short 

niche shows good potential to suppress weeds 

and reduce N fertilizer application (104). 

• Soybeans at leaf-yellowing. Sowing the 

clover seed with annual or perennial ryegrass as a 

nurse crop keeps the soil from drying out until 

the clover becomes established (153). 

Whenever possible, lightly incorporate clover 

seed with a harrow. Wait about six weeks to 

establish a red clover stand in soil treated with 

pre-emergent herbicides such as atrazine. Check 

herbicide labels for rotational crop plant-back 

intervals, and remember that cool temperature 

will slow herbicide breakdown (240). 

Killing 

For peak N contribution, kill red clover at about 

mid-bloom in spring of its second season. If you 

can’t wait that long, you can kill it earlier to plant 

field corn or early vegetables. If you want to harvest 

the first cutting for hay, compost or mulch, 

kill the regrowth in late summer as green manure 

for fall vegetables (153). If avoiding escapes or 

clover regrowth is most important, terminate as 

soon as soil conditions allow. Actively growing 

red clover can be difficult to kill mechanically 

(106), but light fall chisel plowing followed by a 

second such treatment has worked well in sandy 

loam Michigan soils (240). 

To kill clover mechanically in spring, you can 

till,chop or mow it any time after blooming starts. 

You can shallow plow, or use a chisel plow about 

2 to 3 inches deep. Use overlapping shovels, such 

as 16-inch sweeps on shanks spaced 12 inches on 

center. Chop (using a rolling stalk chopper), flail 

or sicklebar mow about seven to 10 days ahead of 

no-till planting, or use herbicides such as atrazine, 

cyanazine, paraquat or glyphosate (25), which 

works best in fall (240). 

A summer mowing can make it easier to kill red 

clover with herbicides in fall. Michigan recommendations 

call for mowing (from mid-August in 

northern Michigan to early September in southern 

Michigan), then allowing regrowth for four 

RED CLOVER 129

shows release may be faster. There, red clover 

and hairy vetch released 70 to 75 percent of their 

N in the first season (329). 


RED CLOVER (Trifolium pratense) 

weeks. If not mechanically killing, spray with 2 

quarts of glyphosate and a quart of 2,4-D ester per 

acre. The daytime high air temperature should be 

above 60 F (so that the plants are actively growing). 

When soil temperature drops below 50 F, 

biological decomposition slows to the point that 

mineralization of N from the clover roots and topgrowth 

nearly stops (183). 

Field Evaluation 

In Michigan, plant counts are used to estimate 

roughly how much N a clover stand will contribute 

to the immediately following crop. The 

formula is 30 + 0.30 x % stand,where 100 percent 

stand is five to six plants per square foot in the 

second year of growth. So a field where your 

counts showed an average of six plants per square 

foot would contribute about 60 lb. N/A (30 + 

[0.30 x 100] 30 = 60). With four plants per square 

foot, percent stand is 4/6 or 66 percent, so the N 

contribution is 50 lb./A (30 + [.30 x 66] 20). 

The Michigan field calculation reflects the conventional 

rule of thumb that about half of the total 

N fixed by a legume will mineralize during the following 

growing season and be available to that 

season’s crop (183). However,Wisconsin research 

Rotations 

Rotation niches for red clover are usually between 

two non-leguminous crops. Spring seeding with 

oats or frostseeding into a wheat crop are common 

options. The intersowing allows economic 

use of the land while the clover is developing. 

This grain/red clover combination often follows 

corn, but also can follow rice, sugar beets, tobacco 

or potatoes in two-year rotations. For threeyear 

rotations including two full years of red 

clover, the clover can be incorporated or surfaceapplied 

(clipped and left on the field) for green 

manure, cut for mulch or harvested for hay (91). 

Red clover in a corn>soybean>wheat/red 

clover rotation in a reduced-input system out-performed 

continuous corn by $53 per acre in a fouryear 

Wisconsin study. The legume cover crop 

system used no commercial fertilizer, no insecticides 

and herbicides on only two occasions— 

once to-spot spray Canada thistles and once as a 

rescue treatment for soybeans. Rotary hoeing and 

cultivating provided weed control. 

Gross margins were $195 for the corn>soybeans>wheat/red 

clover and $151 for continuous 

corn using standard agricultural fertilizers,insecticides 

and herbicides. Top profit in the study went 

to a corn>soybean rotation with a gross margin of 

$209, using standard inputs (218, 326). 


If poor establishment or winterkill leads to weed 

growth that can’t be suppressed with clipping or 

grazing, evaluate whether your anticipated cover 

crop benefits warrant weed control. MCPA is 

labeled for broadleaf weed control in winter 

annuals with clover seedings, but care must be 

taken to avoid seedling injury (183). 

Never plant dry beans or soybeans after clover 

unless the cover has been thoroughly incorporated 

by plowing. Limited herbicide options may be 

unable to control clover escapes that survive in 

the bean crop (183). 

Root rots and foliar diseases typically kill common 

medium red clover in its second year,making 


it function more like a biennial than a perennial. 

Disease-resistant cultivars that persist three to 

four years cost 20 to 40 cents more per pound 

and are unnecessary for most green manure applications. 

When fertilizer N cost is high, however, 

remember that second-year production for some 

improved varieties is up to 50 percent greater 

than for common varieties. 

Bud blight can be transmitted to soybeans by 

volunteer clover plants (295). 

Other Management Options 

Mow or allow grazing of red clover four to six 

weeks before frost in its establishment year to 

prepare it for overwintering. Remove clippings 

for green manure or forage to prevent plant disease. 

Red clover reaches its 

prime feeding value at five to 15 

days after first bloom. Under 

ideal condition, medium red 

clover can be cut four times, 

mammoth only once. Maximum 

cutting of medium one year will 

come at the expense of secondyear 

yield and stand longevity 

(326).Red clover and red clover/ 

grass mixtures make good silage if wilted slightly 

before ensiling or if other preservative techniques 

are used (91). 

If an emergency forage cut is needed,harvest red 

clover in early summer, then broadcast and lightly 

incorporate millet seed with a tine harrow or disk. 

Millet is a heat-loving grass used as a cover and forage 

in warm-soil areas of Zone 6 and warmer (see 

Up-and-Coming Cover Crops, p. 158). 


Medium red clover has similar upper-limit pH tolerance 

as other clovers at about 7.2. It is generally 

listed as tolerating a minimum pH of 6.0—not 

quite as low as mammoth, white or alsike 

(Trifolium hybridum) clovers at 5.5—but it is 

said to do well in Florida at the lower pH (277). 

Few legumes are as 

widely adapted as red 

clover, which can be 

used as green manure, 

forage or seed crop. 

Red clover and sweetclover both perform best on 

well-drained soils, but will tolerate poorly drained 

soils. Alsike thrives in wet soils (306). 

Red clover has less tendency to leach phosphorus 

(P) in fall than some non-legume covers.It 

released only one-third to one-fifth the P of annual 

ryegrass and oilseed radish, which is a winterannual 

brassica cover crop that scavenges large 

amounts of N. Figuring the radish release rates— 

even balanced somewhat by the erosion suppression 

of the covers—researchers determined that 

P runoff potential from a quick-leaching cover 

crop can be as great as for unincorporated 

manure (220). 

For early fall plowdown, alsike clover (with a 

seeding cost of about $9/A) may be a cheaper 

N source than mammoth at 

$15.50/A, assuming similar N 

yields (253). 

Red clover and alfalfa showed 

multi-year benefits to succeeding 

corn crops, justifying a credit 

of 90 lb. N/A the first year for 

red clover (153) and 50 lb. N/A 

the second year (326). The third 

legume in the trial, birdsfoot 

trefoil (Lotus corniculatus), was the only one of 

the three that had enough third-year N contribution 

to warrant a credit of 25 lb. N/A (113). 

SEED 

Cultivars. KENLAND, KENSTAR, ARLINGTON, and 

MARATHON are improved varieties of medium red 

clover with specific resistance to anthracnose and 

mosaic virus strains. They can persist three or 

even four years with ideal winter snow cover 

(65). CHEROKEE is more suited to the Coastal Plain 

and lower South, and has superior resistance to 

rootknot nematode (277). 

Seed sources. Widely available. Companies 

specializing in forage crops have several 

cultivars. 

RED CLOVER 131

SUBTERRANEAN CLOVERS 

Trifolium subterraneum, 

T. yanninicum, 

T. brachycalcycinum 

Also called: Subclover 

Type: reseeding cool season annual 

legume 

Roles: weed and erosion suppressor, 

N source, living or dying 

mulch, continuous orchard floor 

cover, forage 

Mix with: other clovers and 

subclovers 



cool season annual 

spring seeded 

reseeding cool season annual 

fall seeded 

Subterranean clovers offer a range of lowgrowing, 

self-reseeding legumes with high N 

contribution, excellent weed suppression 

and strong persistence in orchards and pastures. 

Fall-planted subclovers thrive in Mediterranean 

conditions of mild, moist winters and dry summers 

on soils of low to moderate fertility, and 

from moderately acidic to slightly alkaline pH. 

Subclover mixtures are used on thousands of 

acres of California almond orchards,where farmers 

continue to evaluate some 50 cultivars for optimum 

combinations. Subclover holds promise in 

the coastal mid-Atlantic and Southeast (Hardiness 

Zone 7 and warmer) on sandy loam to clay soils as 

a killed or living mulch for summer or fall crops. 

Most cultivars require at least 12 inches of rain 

per year. A summer dry period limits vegetative 

growth, but increases hard seed tendency that 

leads to self-reseeding for fall reestablishment. 

Subclovers generally grow close to the ground, 

piling up their biomass in a compact layer. A 

Mississippi test showed that subclover stems were 

about 6, 10 and 17 inches long when the canopy 

was 5, 7 and 9 inches tall, respectively (79). 

Diversity of Types, Cultivars 

Select among the many subclover options cultivars 

that fit your climate and your cover crop 

goals. Identify your need for biomass (for mulch 

or green manure),time of natural dying to fit your 

spring-planting schedule and prominence of seed 

set for a persistent stand. 

Subclovers comprise three Trifolium species: 

• T. subterraneum. The most common cultivars 

that thrive in acid to neutral soils and a 

Mediterranean climate 

• T. yanninicum. Cultivars best adapted to 

water-logged soils 

• T. brachycalcycinum. Cultivars adapted to 

alkaline soils and milder winters 

Primary differences between these species are 

their moisture requirements,seed production and 

days to maturity (15). Other variables include: 

• Overall dry matter yield 

• Dry matter yield at low moisture or low 

fertility 

• Season of best growth (fall, winter or spring) 

• Hard-seeding tendency 

• Grazing tolerance 


Subclover cultivars often are described by their 

moisture preference and days to maturity, which 

are closely linked traits. The maturity estimates 

are set for continuous growing days, and will be 

greatly lengthened for fall-planted subclovers in 

the East and Southeast, where winter weather 

delays flowering for two to three months. 

• Short season subclovers tend to set seed 

quickly. Cultivars such as DALKEITH (an improved 

version of DALIAK) and NUNGARIN need only 8 to 10 

inches of rainfall and set seed about 85 days after 

planting. Early subclovers tend to be less winter 

hardy (77). 

• Intermediate types such as TRIKKALA and the 

new,more competitive GOSSE thrive with 14 to 20 

inches of rain and set mature 

seed in about 100 days. 

• Long-season cultivars such 

as KARRIDALE and NANGEELA perform 

best with 18 to 26 inches 

of rainfall, setting seed in about 

130 days. MT.BARKER was a longtime 

research standard that is 

now surpassed by KARRIDALE for forage production, 

hardseed percentage, re-establishment potential 

and grazing. KARRIDALE is more prostrate, 

and is favored for cover crop use (345). 

BENEFITS 

Weed suppressor. Subclover can produce 3,000 

to 8,500 lb. dry matter/A in a thick mat of stems, 

petioles (structures connecting leaves to stems) 

and leaves. Denser and less viny than hairy vetch, 

it also persists longer as a weed-controlling 

mulch. 

Subclover mixtures help West Coast orchardists 

achieve season-long weed management. In Coastal 

California, fast-growing TRIKKALA, a mid-season cultivar 

with a moderate moisture requirement,jumps 

out first to suppress weeds and produces about 

twice as much winter growth during January and 

February as the other subclovers. It dies back naturally 

as KOALA, (tall) and KARRIDALE (short) come on 

strong in March and April. The three cultivars 

complement each other spatially and temporally 

for high solar efficiency,similar to the interplanting 

of peas, purple vetch, bell beans and oats in 

Subclovers thrive in 

Mediterranean climates 

of mild, moist winters 

and dry summers. 

California vegetable fields where a high-residue, 

high-N cover is desired (345). 

In legume test plots along the Maryland shore, 

subclover mulch controlled weeds better than 

conventional herbicide treatments. The only 

weed to penetrate the subclover was a fall infestation 

of yellow nutsedge.The cover crop regrew 

in fall from hard seed in the second and third 

years of the experiment (19). 

Green manure. In east Texas trials, subclover 

delivered 100 to 200 lb. N/A after spring plowdown. 

Grain sorghum planted into incorporated 

subclover or berseem clover with no additional N 

yielded about the same as sorghum planted into 

disked and fertilized soil without 

a cover crop in three out of 

four years. The fertilized fields 

had received 54 lb. N/A (192). 

Versatile mulch. Subclover 

provides two opportunities for 

use as a mulch in vegetable systems. 

In spring, you can no-till early planted crops 

after subclover has been mechanically or chemically 

killed, or plant later, after subclover has set 

seed and dried down naturally (19). In fall, you 

can manage new growth from self reseeding to 

provide a green living mulch for cold-weather 

crops such as broccoli and cauliflower (165). 

Conventionally tilled corn without a cover crop 

in a New Jersey test leached up to 150 lb. N/A 

over winter while living subclover prevented N 

loss (99). Mowing was effective in controlling a 

living mulch of subclover in a two-year California 

trial with late-spring, direct-seeded sweet corn 

and lettuce.This held true where subclover stands 

were dense and weed pressure was low. Planting 

into the subclover mulch was difficult, but was 

done without no-till equipment (189). 

Soil loosener. In an Australian study in compaction-prone 

sandy loam soil, lettuce yield doubled 

following a crop of subclover. Without the 

clover, lettuce yields were reduced 60 percent on 

the compacted soil.Soil improvement was credited 

to macropores left by decomposing clover roots 

and earthworms feeding on dead mulch (323). 

SUBTERRANEAN CLOVERS 133

levels, and nine other subclover cultivars had 

lower levels than the crimson (38). 

Elayne Sears 

SUBTERRANEAN CLOVER 

(Trifolium subterraneum) 

Great grazing. Subclovers are highly palatable 

and relished by all livestock (91). Seeded with 

perennial ryegrass,tall fescue or orchardgrass,subclovers 

add feed value as they improve productivity 

of the grasses by fixing nitrogen. In 

California, subclover is used in pasture mixtures 

on non-irrigated hills. Perennial ryegrass is preferred 

for pasture through early summer, especially 

for sheep (249). 

Insect pest protection. In the Netherlands, subclover 

and white clover in cabbage suppressed 

pest insect egg laying and larval populations 

enough to improve cabbage quality and profit 

compared with monocropped control plots. 

Eliminating pesticide costs offset the reduced 

weight of the cabbages in the undersown plots. 

Primary pests were Mamestra brassicae, 

Brevicoryne brassicae and Delia brassicae. 

Undersowing leeks with subclover in the 

Netherlands greatly reduced thrips that cannot be 

controlled by labeled insecticides, and slightly 

reduced leek rust,a disease that is difficult to control. 

While leek quality improved, the quantity of 

leeks produced was reduced considerably (344). 

When tarnished plant bug (Lygus lineolaris) is 

a potential pest, subclover may be the legume 

cover crop of choice, based on a Georgia comparison 

among subclovers, hybrid vetches and 

crimson clover. MT. BARKER had particularly low 

Home for beneficial insects. In tests of eight 

cover crops or mixtures intercropped with cantalope 

in Georgia, MT. BARKER subclover had the 

highest population of big-eyed bugs (Geocorus 

punctipes), a pest predator. Subclover had significantly 

higher numbers of egg masses of the predator 

than rye, crimson clover and a polyculture of 

six other cover crops, but not significantly higher 

than for VANTAGE vetch or weedy fallow. While 

the covers made a significant difference in the 

predator level, they did not make a significant 

difference in control of the target pest, fall armyworm 

(Spodoptera frugiperda) (38). 

Erosion fighter. Subclover’s soil-hugging, dense, 

matted canopy is excellent for holding soil (77). 

Disease-free. No major diseases restrict subclover 

acreage in the U.S. (15). 

MANAGEMENT 

Establishment 

Subclovers grow best when they are planted in 

late summer or early autumn and grow until 

early winter. They go dormant over winter and 

resume growth in early spring. In late spring, 

plants flower and seeds mature in a bur at or 

below the soil surface (hence the name subterranean 

clover) as the plant dries up and dies. A 

dense mulch of dead clover leaves and long petioles 

covers the seeds, which germinate in late 

summer to establish the next winter’s stand 

(98). Their persistence over many seasons 

justifies the investment in seed and careful 

establishment. 

In California, sow in September or early 

October to get plants well established before cool 

weather (249). Planting continues through 

November in the most protected areas (281). 

In marginally mild areas, establish with grasses 

for winter protection. Subclover stimulates the 

grasses by improving soil fertility. You can overseed 

pasture or range land without tillage,but you 

can improve germination by having livestock 


trample in the seed. Subclover often is aerially 

applied to burned or cleared land. Initial growth 

will be a little slower than that of crimson, but a 

little faster than white clover (91). 

Broadcast at 20-30 lb./A in a well-prepared, 

weed-free seedbed that is firm below a depth of 

2 inches. Cover seed with a light, trailing harrow 

or with other light surface tillage to a depth of 

less than one-half inch. Add lime if soil is highly 

acid—below pH 5.5 (249). Soils low in pH may 

require supplemental molybdenum for proper 

growth, and phosphorus and sulfur may also be 

limiting nutrients. Only the T. yanninicum cultivars 

will tolerate standing water or seepage 

areas (15, 249). 

Subclover often is planted 

with rose clover and crimson 

clover in California orchard 

mixes. Crimson and subclover 

usually dominate, but 

hard-seeded rose clover persists 

when dry weather knocks out the other 

two (368). 

In the East, central Mississippi plantings are 

recommended Sept. 1 to Oct. 15, although earlier 

plantings produce the earliest foliage in spring 

(91).In coastal Maryland where MT.BARKER plants 

were tallest and most lush, winterkill (caused 

when the temperature dropped to 15 F or 

below) has been most severe. Planting in this 

area of Zone 7 should be delayed until the first 

two weeks of October. Plant at about 22 lb./A for 

cover crop use in the mid-Atlantic (19) and 

Southeast (77). This is about double the usual 

recommended rate for pastures in the warmer 

soils of the Southeast. 

Small plants of ground-hugging subclover benefit 

more from heat radiating from the soil than 

larger plants, but are more vulnerable during 

times of freezing and thawing.Where frost heaving 

is expected, earlier planting and well-established 

plants usually survive better than smaller 

ones (77). 

Killing 

Subclover dies naturally in early summer after 

blooming and seed set. It is relatively difficult to 

kill without deep tillage before mid-bloom stage. 

Subclover mixes help keep 

weeds in check all season 

long in West Coast orchards. 

After stems get long and seed sets, you can kill 

plants with a grain drill (77). 

In northern Mississippi, subclover was the least 

controlled of four legumes in a mechanical kill 

test. The cover crops were subjected to being 

rolled with coulters spaced 4 inches apart when 

the plants had at least 10 inches of prostrate 

growth. While hairy vetch and crimson clover 

were 80 to 100 percent controlled, berseem 

control was 53 percent and subclover was 

controlled only 26 to 61 percent (79). 

Researchers in Ohio had no trouble killing 

post-bloom subclover with a custom-built undercutter.The 

specialized tool is made to slice 1 to 2 

inches below the surface of 

raised beds.The undercutter 

consisted of two blades 

that are mounted on upright 

standards on either side of 

the bed and slant backward 

at 45 degrees toward the 

center of the bed.A mounted rolling harrow was 

attached to lay the cover crop flat on the surface 

after being cut (70). The tool, which continues to 

be modified,severs stalks from roots while aboveground 

residue is undamaged, greatly slowing 

residue decomposition (69). 

Glysophate and dicamba (25) materials work 

better for controlling subclover than do paraquat 

(77) and 2,4-D (186). Subclover tolerance to herbicides 

varies with cultivar and growth stage. 

Generally, subclover is easier to kill after it has set 

some seed (78, 130). 

Reseeding Management 

The “over-summering”fate of reseeding subclover 

plantings is as critical to their success as is the 

over-wintering of winter-annual legumes. The 

thick mat of vegetation formed by dead residue 

can keep subclover seeds dormant if it is not disturbed 

by grazing,tillage,burning or seed harvest. 

Where cover crop subclover is to be grazed 

before another year’s growth is turned under, 

intensive grazing management works best to 

reduce residue but to avoid excess seed bur consumption 

(249). Grazing or mowing in late spring 

or early summer helps control weeds that grow 

through the mulch (234). 


You can improve volunteer regrowth of subclover 

in warm-season grass mixes by limiting N 

fertilization during summer, and by grazing the 

grass shorter until cold temperatures limit grass 

growth. This helps even though subclover 

seedlings may emerge earlier (15). Seed production 

in Oregon was best following grazing from 

just prior to the start of flowering until the time 

of early bur fill (15). Subclover flowers are inconspicuous 

and will go unnoticed without careful, 

eye-to-the-ground inspection (77). 

After plants mature, livestock will eagerly eat 

seed heads (91). In dry years when you want to 

maintain the stand, limit grazing over summer to 

avoid over-consumption of seed heads and depletion 

of the seed bank. Close mowing or grazing 

can be done any time. 

Some subclover seed (primarily MT.BARKER) is 

produced in Oregon and sold locally for forage 

use. Most commercial subclover seed is produced 

in Australia. Subclover cultivars were developed 

there for use in “ley” cropping. In this system, 

sheep or other livestock graze the legume for 

several years. Then the land is cropped briefly 

before being pastured again as the hard seeds of 

subclover re-establish a stand. 

Management Challenges 

Possible crop seedling suppression. The 

allelopathic compounds that help subclover suppress 

weeds also can hurt germination of some 

crops.To avoid problems with these crops, delay 

planting or remove subclover residue. No-till 

planters equipped with tine-wheel row cleaners 

can reduce the recommended 21-day waiting 

period that allows allelopathic compounds to 

drop to levels that won’t harm crops (75). Kill 

subclover at least a year before planting peach 

trees to avoid a negative effect on seedling vigor. 

It’s best to wait until August of the trees’ second 

summer to plant subclover in row middles, an 

Arkansas study found (43). 

The degree to which a cover crop mulch 

hinders vegetable seedlings is crop specific. Planttoxic 

compounds from subclover mulch suppressed 

lettuce,broccoli and tomato seedlings for eight 

weeks, but not as severely or as long as did compounds 

from ryegrass (Lolium rigidum cv. 

WIMMERA) mulch. An alfalfa mulch showed no such 

allelopathic effect in an Australian study (323). 

Guard against moisture competition from 

subclover at planting. Without irrigation to 

ensure crop seeds will have enough soil moisture 

to germinate in a dry year, be sure that the 

subclover is killed seven to 14 days prior to 

planting to allow rainfall to replenish soil 

moisture naturally (19). 

Soil-borne crop seedling disease. In north 

Mississippi tests, residue and leachate from 

legume cover crops (including subclover) caused 

greater harm to grain sorghum seedlings, compared 

to nonlegumes. Rhizoctonia solani, a soilborne 

fungus, infected more than half the 

sorghum seedlings for more than a month, but 

disappeared seven to 13 days after legume 

residues were removed (75). 

N-leaching. The early and profuse nodulation of 

subclovers that helps grass pastures also has a 

downside—excess N in the form of nitrate can 

contaminate water supplies. Topgrowth of subclover, 

black medic and white clover leached 12 

to 26 lb.N/A over winter,a rate far higher than red 

clover and berseem clover, which leached only 2 

to 4 lb. N/A in a Swedish test (181). 


Subclovers showed little resistance to root-knot 

nematodes in Florida tests on 134 subclover lines 

in three years of testing the most promising 

varieties (186). 

Lygus species, important pests of field, row 

and orchard crops in California and parts of the 

Southeast, were notably scarce on subclover 

plants in a south Georgia comparison. Other 

legumes harboring more of the pests were, in 

descending order, CAHABA and VANTAGE vetch, 

hairy vetch, turnip and monoculture crimson 

clover (38). 

Most cultivars imported to the U.S. are low 

in estrogen, which is present in sufficient levels 

in some Australian cultivars to reduce fertility 

in ewes, but not in goats or cattle. Confirm estrogen 

status of a cultivar if you plan to graze sheep 

on it (249). 


Crop Systems 

Interseeded with wheat. NANGEELA subclover 

provided 59 lb. N/A when it was grown as an 

interseeded legume in soft red winter wheat in 

eastern Texas. That extra N helped boost the 

wheat yield 283 percent from the previous year’s 

yield when four subclover cultivars were first 

established and actually decreased yield, compared 

with a control plot. NANGEELA, MT. BARKER, 

WOOLGENELLUP and NUNGARIN cultivars boosted 

wheat yield by 24, 18, 18, and 11 bu./A, respectively, 

in the second year of the study. Over all 

three years, the four cultivars added 59, 51, 38 

and 24 lb. N/A, respectively (29). 

Plant breeder Gerald Ray Smith of Texas A&M 

University worked with several subclovers in eastern 

Texas. While the subclovers grew well the 

first year,he concluded that those cultivars need a 

prolonged dry period at maturity to live up to 

their reseeding performance in Australia and 

California. Surface moisture at seed set reduces 

seed hardening and increases seed decay. Midsummer 

rains cause premature germination that 

robs the subclover seed bank, especially in pastures 

where grasses tend to create moist soil 

(318). Most summer-germinating plants die when 

dry weather returns. 

In Mississippi, subclover hard seed development 

has been quite variable from year to year. In 

dry years, close to 100 percent hard seed is developed. 

Dormancy of the seed breaks down more 

rapidly on bare soil with wider temperature 

swings than it does on mulched soils (100, 101). 

To facilitate reseeding or to seed into pastures,the 

grasses must be mowed back or grazed quite 

short for the subclover to establish (77). 

Mix for persistence. California almond growers 

need a firm, flat orchard floor from which to pick 

up almonds. Many growers use a mix of moisturetolerant 

TRIKKALA, alkaline-tolerant KOALA, and 

KARRIDALE, which likes neutral to acid soils.These 

blended subclovers give an even cover across 

moist swails and alkaline pockets (345). 

Rice N-source. In Louisiana trials, subclover 

regrew well in fall when allowed to set seed 

before spring flooding of rice fields. Compared 

with planting new seed, this method yields larger 

seedling populations, and growth usually begins 

earlier in the fall. The flood period seems to 

enhance dormancy of both subclover and crimson 

clover, and germination is robust when the 

fields are drained (77). Formerly, some Louisiana 

rice farmers seeded the crop into dry soil then let 

it develop for 30 days before flooding. Early varieties 

such as DALKEITH and NORTHAM may make 

seed prior to the recommended rice planting 

date. In recent decades,“water planting” has been 

used to control red rice, a weedy relative of 

domestic rice. Water seeding into cover crop 

residues has not been successful (22). 

Fertility, weed control for corn. In the humid 

mid-Atlantic region, grain and silage corn no-tilled 

into NANGEELA subclover did well in a six-year 

New Jersey trial. With no additional N, the subclover 

plots eventually out-yielded comparison 

plots of rye mulch and bare-soil that were conventionally 

tilled or minimum-tilled with fertilizer 

at up to 250 lb. N/A. The subclover contributed 

up to 370 lb. N/A (99), an N supply requiring 

careful management after the subclover dies to 

prevent leaching. 

Control of fall panicum was poor in the first 

year, but much better the next two years. Control 

of the field’s other significant weed, ivyleaf morning 

glory, was excellent in all years. Even though 

no herbicide was used in the subclover plots, 

weed biomass was lowest there (99). 

Central New Jersey had mild winters during 

these experiments. Early spring thaws triggered 

subclover regrowth followed by plunging temperatures 

that dropped below 15 F. This weakened 

the plants and thinned the stands. The 

surviving plants, which formed dense stands at 

times, were mowed or strip-killed using herbicides 

or tillage. Mowing often induced strong 

regrowth, so strips at least 12 inches wide proved 

to be the best to prevent moisture competition 

between the subclover and the cabbage and 

zucchini transplants (165). 

Sustainable sweet corn. On Maryland’s Eastern 

Shore (one USDA hardiness zone warmer than 

New Jersey), University of Maryland Weed 


Specialist Ed Beste reported good reseeding in 

four consecutive years and no problems with 

stand loss from premature spring regrowth. 

Overwintering MT.BARKER plants sent out stolons 

across the soil surface to quickly re-establish a 

good stand ahead of sweet corn plantings (19). 

Beste believes the sandy loam soil with a sand 

underlayer at his site is better for subclover than 

the heavier clay soils at the USDA Beltsville station 

some 80 miles north, where hairy vetch usually 

out-performs subclover as a killed organic mulch in 

transplanted vegetable systems.Winterkill reduced 

the subclover stand on top of bedded rows one 

year of the comparison, yet surviving plants 

between the beds produced nearly as much 

biomass per square foot as did hairy vetch (1). 

Beste has worked with subclover at his 

Salisbury, Md., site for several years, seeding vegetables 

in spring, early summer and mid-summer 

into the killed or naturally dead cover crop 

mulch. For three years, subclover at Beste’s sweet 

corn system comparison site yielded about 5,400 

lb. DM/A. Without added N, the subclover plots 

yielded as much sweet corn as conventional plots 

receiving 160 lb. N/A. Weed suppression also was 

better than in the conventional plots. He sprayed 

glyphosate on yellow nutsedge in fall to prevent 

tuber formation by the grassy weed, the only 

weed that penetrated the subclover mulch (19). 

Beste sprays paraquat twice to control subclover 

ahead of no-till, direct seeded zucchini in 

the first week of June. His MT.BARKER will set seed 

and die back naturally at the end of June—still in 

time to seed pumpkins, fall cucumbers, snap 

beans or fall zucchini planted without herbicides 

(19).Such a no-chemical/dying mulch/perpetually 

reseeding legume system is the goal of cultivar 

and system trials in California (346). 

Seed production in subclovers normally is triggered 

by increasing day length in spring after the 

plant experiences decreasing fall day length 

(346). This explains why spring-planted subclover 

in Montana tests produced profuse vegetative 

growth,especially when fall rains began,but failed 

to set any seed (316). Stress from drought and 

heat also can trigger seed set. 


White and arrowleaf clovers have proved to be 

better self-reseeding clovers than subclover in the 

humid South because their seed is held in the air, 

giving them a better chance to harden (320). 

Top reseeding contenders are balansa clover (see 

Up-and-Coming Cover Crops, p. 158.) and southern 

spotted bur medic (see Southern Spotted Bur 

Medic Offers Reseeding Persistence, p. 122). 

While mid-season subclovers generally produced 

more dry matter and N than medics for 

dryland cereal-legume rotations in Montana 

(314), they did not set seed when grown as summer 

annuals in the region. Summer growth continued 

as long as moisture held up in trials there. 

Vegetative growth increased until frost, as cool, 

moist fall weather mimicks the Mediterranean 

winter conditions where subclover thrives (316). 

CLARE is a cultivar of the subclover subspecies 

brachycalycinum.Compared with the more common 

subspecies subterranean (SEATON PARK and 

DALIAK), CLARE has vigorous seedlings, robust 

growth when mowed monthly and is said to tolerate 

neutral to alkaline soils. However, it appears 

to be less persistent than other types (43). 

Subclover,rye and crimson clover provided grass 

weed control that was 46 to 61 percent better than 

a no-cover/no-till system at two North Carolina 

locations. Subclover topped the other covers in 

suppressing weeds in plots where no herbicides 

were used. None of the cover crop treatments 

eliminated the need for pre-emergent herbicides 

for economic levels of weed control (373). 

Subclover creates a tighter mat of topgrowth 

than vetch (19) or crimson clover (77). 

SEED 

Cultivars. See Comparative Notes, above, and 

Diversity of Types, Cultivars (p. 132). 

Seed sources. Adams-Briscoe, Ampac, Budd, 

Kamprath, Kaufman, Peaceful Valley. See Seed 

Suppliers (p. 166). 


SWEETCLOVERS 

Yellow sweetclover (Melilotus 

officinalis) and white 

sweetclover (M. alba) 

Also called: HUBAM (actually a cultivar 

of annual white sweetclover) 

Type: biennial, summer annual 

or winter annual legume 

Roles: soil builder, fertility source, 

subsoil aerator, weed suppressor, 

erosion preventer 

Mix with: small grains 



biennial 

spring sown 

biennial 

fall sown 

marginal area 

Within a single season on even marginally 

fertile soils, this tall-growing biennial 

produces abundant biomass and moderate 

amounts of nitrogen as it thrusts a taproot 

and branches deep into subsoil layers. Given fertile 

soils and a second season, it lives up to its full 

potential for nitrogen and organic matter production. 

Early in the second year it provides new top 

growth to protect the soil surface as its roots 

anchor the soil profile. It is the most drought-tolerant 

of forage legumes, is quite winter-hardy and 

can extract from the soil then release phosphorus, 

potassium and other micronutrients that are 

otherwise unavailable to crops. 

Sweetclover thrives in temperate regions wherever 

summers are mild. Annual sweetclovers 

(HUBAM is the most well known) work best in the 

Deep South, from Texas to Georgia. There, they 

establish more quickly than the biennial types and 

produce more biomass in the seeding year in 

southern regions. 

In this chapter,“sweetclover” refers to biennial 

types unless otherwise noted. 

Sweetclover was the king of green manures 

and grazing legumes in the South and later 

throughout the Midwest in the first half of this 

century. Sweetclover is used as a cover crop most 

commonly now in the Plains region,with little use 

in California. 

Types 

Biennial yellow sweetclover can produce up to 24 

inches of vegetative growth and 2.5 tons dry matter/A 

in its establishment year. During the second 

year, plants may reach 8 feet tall. Root mass and 

penetration (to 5 feet) are greatest at the end of 

dormancy in early spring, then gradually dissipate 

through the season (365). 

A distinguishing sweetclover feature is bracts of 

tiny blooms through much of its second year. 

White biennial sweetclovers are taller, more 

coarsely stemmed, less drought tolerant, and produce 

less biomass in both the seeding and second 

years.White types bloom 10 to 14 days later than 

yellow, but bloom for a longer season. They 

reportedly establish more readily in New York 

(370). Tall, stemmy cultivars are better for soil 

improvement (91, 302, 351). 

Both yellow and white sweetclover have cultivars 

bred for low levels of coumarin. This com- 

SWEETCLOVERS 139

legume roots and fallow leaching, whereas spring 

wheat could not.The vesicular-arbuscular mycorrhizal 

(VAM) fungi associated with legume roots 

contribute to the increased P availability associated 

with sweetclover (49, 50). 


YELLOW SWEETCLOVER (Melilotus officinalis) 

pound exists in bound form in the plant and 

poses no problem during grazing. However, 

coumarin can cause internal injury to cattle when 

they eat spoiled sweetclover hay or silage. 

Annual sweetclover (M.alba var. annua) is not 

frost tolerant, but can produce up to 9,000 lb. dry 

matter/A over a summer after being oversown 

into a grain crop or direct seeded with a spring 

grain nurse crop. The best-known annual sweetclover 

cultivar is HUBAM, a name often used for all 

annual white sweetclover. While its taproot is 

shorter and more slender than that of its biennial 

cousins, it still loosens subsoil compaction. 

BENEFITS 

Nutrient scavenger. Sweetclover appears to 

have a greater ability to extract potassium, phosphorus 

and other soil nutrients from insoluble 

minerals than most other cover crops. Root 

branches take in minerals from seldom-disturbed 

soil horizons, nutrients that become available as 

the tops and roots decompose (302). 

Research in Saskatchewan during a 34-year 

period showed that phosphorus (P) availability 

increased in subsoil layers relative to surface layers, 

peaking at an 8-foot depth.Winter wheat and 

safflower, with deeper root systems than spring 

wheat, could tap the deep P buildup from the 

N source. A traditional green manure crop in the 

upper Midwest before nitrogen fertilizer became 

widely available, sweetclover usually produces 

about 100 lb. N/A, but can produce up to 200 lb. 

N/A with good fertility and rainfall. Illinois 

researchers reported more than 290 lb. N/A. 

Abundant biomass. If planted in spring and 

then given two full seasons,biennial sweetclovers 

can produce 7,500 to 9,000 lb. dry matter/A 

(3,000 to 3,500 lb./A in the seeding year, and 

4,500 to 5,500 lb./A the second). Second-year 

yields may go as high as 8,500 lb./A. 

Hot-weather producer. Sweetclover has the 

greatest warm-weather biomass production of 

any legume, exceeding even alfalfa (306). 

Soil structure builder. Kansas farmer Bill 

Granzow says sweetclover gives his soils higher 

organic matter, looser structure and better 

tilth (126). See Sweetclover: Good Grazing, Great 

Green Manure (p. 142). HUBAM annual sweetclover 

also improved soil quality and increased 

yield potential in 1996 New York trials (371). 

Compaction fighter. Yellow sweetclover has a 

determinate taproot root up to 1 foot long with 

extensive branches that may penetrate 5 feet to 

aerate subsoils and lessen the negative effects of 

compaction on crops.White types have a strong 

tap root that is not determinate (125). 

Inexpensive. Establishment costs of about 

$11/A are one-half to one-fifth that of other major 

legume cover crops. 

Drought survivor. Once established, sweetclover 

is the most drought tolerant of all cover 

crops that produce as much biomass. It is especially 

resilient in its second year, when it could do 

well in a dry spring during which it would be 


difficult to establish annual cover crops.The yellow 

type is less sensitive to drought and easier to 

establish in dry soils than the white type (125). 

Attracts beneficial insects. Blossoms attract 

honeybees, tachinid flies and large predatory 

wasps, but not small wasps. 

Widely acclimated. Self-reseeding sweetclover 

can be seen growing on nearly barren slopes,road 

rights-of-way, mining spoils and soils that have 

low fertility, moderate salinity or a pH above 6.0 

(141). It also can tolerate a wide range of environments 

from sea level to 4,000 feet in altitude, 

including heavy soil, heat, insects, plant diseases 

(91) and as little as 6 inches of rain per year. 

Livestock grazing or hay. If you need emergency 

forage, sweetclover has a first-year feed 

value similar to alfalfa,with greater volume of lesser 

quality in the second year. 

MANAGEMENT 

Establishment & Field Management 

Sweetclover does well in the same soils as alfalfa. 

Loam soils with near-neutral pH are best. Like 

alfalfa, it will not thrive on poorly drained soils. 

For high yields, sweetclover needs P and K in the 

medium to high range. Deficient sulfur may limit 

its growth (116). Use an alfalfa/sweetclover 

inoculant. 

In temperate areas of the 

Corn Belt, drill yellow sweetclover 

in pure stands at 8 to 15 

lb./A or broadcast 15 to 20 

lb./A, using the higher rate in 

dry or loose soils or if not 

incorporating. 

In drier areas such as eastern 

North Dakota, trials of seeding rates from 2 to 20 

lb./A showed that just 4 lb./A, broadcast or drilled, 

created an adequate sole-crop stand for maximum 

yield.Recommended rates in North Dakota are 4 to 

6 lb./A drilled with small grains at small-grain planting, 

5 to 8 lb./A broadcast and harrowed (sometimes 

in overseeding sunflowers),and 6 to 10 lb./A. 

broadcast without incorporating tillage (141). 

Winter-hardy and drought 

tolerant, this biennial can 

produce up to 200 lb. N/A 

with good fertility and 

rainfall. 

An excessively dense stand will create spindly 

stalks that don’t branch or root to the degree that 

plants do in normal seedings. Further, the plants 

will tend to lodge and lay over, increasing the risk 

of diseases. So for maximum effect of subsoil 

penetration or snow trapping, go with a lighter 

seeding rate. 

Sweetclover produces 50 percent or more hard 

seed that can lie in soil for 20 years without germinating. 

Commercial seed is scarified to break 

this non-porous seedcoat and allow moisture to 

trigger germination. If you use unscarified seed, 

check hardseed count on the tag and do not 

count on more than 25 percent germination from 

the hardseed portion. The need for scarification 

to produce an adequate stand may be over-rated, 

however. The process had no effect on germination 

in six years of field testing in North Dakota— 

even when planting 70 percent hard seed still in 

seed pods (214). 

Seed at a depth of 1 /4 to 1 /2 inch in medium to 

heavy textured soils, and 1 /2 to 1.0 inch on sandy 

soils. Seeding too deeply is a common cause of 

poor establishment. 

Seed annual white sweetclover at 15 to 30 

pounds per acre. Expect 70 to 90 lb. N/A from 

4,000 to 5,000 lb. dry matter/A on well-drained, 

clay loam soils with neutral to alkaline pH. 

A press-wheel drill with a grass seed attachment 

and a seed agitator is suitable for planting 

sweetclover into a firm seedbed. 

If the seedbed is too 

loose to allow the drill to regulate 

seeding depth, run the 

seed spouts from the grass 

and legume boxes to drop 

seed behind the double-disk 

opener and in front of the 

press wheels. Light, shallow 

harrowing can safely firm the 

seedbed and incorporate seed (141). 

If your press-wheel drill has no legume box or 

grass-seed attachment, you can mix the legume 

and small grain seed. Reduce competition 

between the crops by seeding a part of the companion 

crop first, then seed a mix of the clover 

seed and the balance of the grain seed at right 

angles (141). 

SWEETCLOVERS 141

Sweetclover: Good Grazing, Great Green Manure 

Bill Granzow taps biennial yellow and white pounds of N to the soil. He knocks back 

sweetclovers to enhance soil tilth, control 

persistent re-growing sweetclover crowns 

erosion and prevent subsoil from becoming in the sorghum by adding 2, 4-D or Banvel 

compacted. He works with a common variety to the postemerge herbicide mix. 

that his father originally bought from a 

• Green manure/fallow. Disk at-mid to full 

neighbor. 

bloom, summer fallow then plant wheat 

Granzow, of Herington, Kan., produces grain again in fall.This method provides about 

and runs cattle in an area midway between 

120 lb. N/A, according to estimates from 

Wichita and Manhattan in the east-central 

Kansas State University. Disking or other 

part of the state. 

light tillage controls weeds that may 

Granzow overseeds sweetclover into winter emerge with sufficient rainfall. 

wheat in December or January at 12 to 15 • Seed crop. He windrows the plants when 

lb./A using a rotary broadcaster mounted on about 50 percent of the seedpods have 

his pickup. Sometimes he asks the local grain turned black, then runs the stalks through 

cooperative to mix the seed with his urea 

his combine.To remove all of the hulls, 

fertilizer for the wheat. There’s no extra 

he runs the seed through the combine a 

charge for seed application. Granzow also 

second or third time. 

plants sweetclover at the same rate with 

Despite the heavy growth in the second 

March-seeded oats. 

year, yellow sweetclover matures and dies 

Yellow sweetclover has overgrown 

back naturally.Two or more passes with his 

Granzow’s wheat only when the wheat 

496 International disk with smooth 21-inch 

stand is thin and abnormally heavy rains delay blades on 9 inch spacings does an adequate 

harvest.The minimal problem is even more job to prepare for fall planting. 

rare in oats, he says. 

Granzow sows sorghum following 

He uses yellow sweetclover with the 

sweetclover with an 800 International Cycloplanter 

with small furrow openers.Another 

companion wheat crop in four possible ways, 

depending on what the field needs or what option would be to use a no-till planter after 

other value he wants to maximize. For each, herbicide desiccation, he says. 

he lets the clover grow untouched after wheat He rates fall sweetclover hay from the 

harvest for the duration of the seeding year. seeding year as “acceptable forage.” He’s 

Second-year options include: 

aware that moldy sweetclover hay contains 

• Grazing/green manure. Turn in livestock coumarin, a compound that can kill cattle, but 

when the clover reaches 4 inches tall, let he’s never encountered the problem. Secondyear 

yellow sweetclover makes silage at initial 

them graze for several weeks, then disk 

several times before planting grain sorghum. to mid-bloom stage with 16 percent protein 

He feeds an anti-bloat medication to keep on a dry matter basis.“Mixed with grass hay 

cattle healthy on the lush legume forage. or other silage, it makes an excellent feed,” he 

• Quick green manure. Disk at least twice says, adding value to its cover crop benefits 

after it has grown 3 to 4 inches, then plant and giving him farming flexiblity. 

sorghum.This method contributes about 60 


Spring seeding provides yellow sweetclover 

ample time to develop an extensive root system 

and store high levels of nutrients and carbohydrates 

necessary for over-wintering and robust 

spring growth. It grows slowly the first 60 days 

(116). Where weeds would be controlled by 

mowing, no-till spring seeding in small grain 

stubble works well. 

Broadcast seeding for pure sweetclover stands 

works in higher rainfall areas in early spring 

where soil moisture is adequate for seven to 10 

days after planting. No-till seeding works well in 

small grain stubble. 

Frostseeding into winter grains allows a harvest 

of at least one crop during the life cycle of the 

sweetclover and helps control weeds while the 

sweetclover establishes. Apply sweetclover seed 

before rapid stem elongation of the grain. Cut 

grain rate about one-third when planting the 

crops together. 

Sweetclover spring seeded with oats exhibited 

poor regrowth after oat harvest in two years of a 

Wisconsin study. To establish a sweetclover 

cover crop in this way, the researchers found 

sweetclover did not fare well in years when the 

combine head had to be run low to pick up 

lodged oats. When oats remained upright (sacrificing 

some straw for a higher cut), sweetclover 

grew adequately (330). 

You can plow down spring-planted yellow 

sweetclover in late fall of the planting year to cash 

in early on up to half its N contribution and a bit 

less than half its biomass. 

Plant biennial sweetclover through late 

summer where winters are mild, north through 

Zone 6. Plant at least six weeks before frost so 

roots can develop enough to avoid winter heaving. 

See Sweetclover: Good Grazing, Great Green 

Manure (p. 142). 

First-year management. Seeding year harvest 

or clipping is usually discouraged, because the 

energy for first-year regrowth comes directly from 

photosynthesis (provided by the few remaining 

leaves), not root reserves (302). Seeding year clipping 

before Aug. 15 in North Dakota can boost 

biomass production by 50 percent, but virtually 

no sweetclover is currently clipped in the first 

year (214). 

Top growth peaks in late summer as the plant’s 

main taproot continues to grow and thicken. 

Second-year growth comes from crown buds that 

form about an inch below the soil surface.Avoid 

mowing or grazing of sweetclover in the six- to 

seven-week period prior to frost when it is building 

final winter reserves. Root production practically 

doubles between Oct.1 and freeze-up (125). 

Sweetclover establishes well when sown with 

winter grains in fall, but it can outgrow the grain 

in a wet season and complicate harvest. 

Second-year management.After it breaks winter 

dormancy,sweetclover adds explosive and vigorous 

growth. Stems can reach 8 feet before 

flowering, but if left to mature, the stems become 

woody and difficult to manage. Plants may grow 

extremely tall in a “sweetclover year” with high 

rainfall and moderate temperatures. 

Nearly all growth the second year is topgrowth, 

and it seems to come at the expense of root mass. 

From March to August in Ohio, records show topgrowth 

increasing tenfold while root production 

decreased by 75 percent (125, 365). All crown 

buds initiate growth in spring. If you want 

regrowth after cutting, leave plenty of stem buds 

on 6 to 12 inches of stubble. You increase the risk 

of killing the sweetclover plant by mowing heavier 

stands, at shorter heights, and/or at later 

growth stages, especially after bloom (141). 

Before it breaks dormancy, sweetclover can 

withstand flooding for about 10 days without 

significant stand loss. Once it starts growing, 

however, flooding will kill the plants (141). 

Killing 

For best results ahead of a summer crop or fallow, 

kill sweetclover in the second year after seeding 

when stalks are 6 to 10 inches tall (141, 302). 

Killing sweetclover before bud stage has several 

benefits: 80 percent of the potential N is present; 

N release is quick because the plant is still quite 

vegetative with a high N percentage in young 

stalks and roots; and moisture loss is halted without 

reducing N contribution. Sweetclover may 

SWEETCLOVERS 143

egrow from healthy crowns if incorporated 

before the end of dormancy.For optimum full-season 

organic matter contribution, mow prior to 

blossom stage whenever sweetclover reaches 12 

to 24 inches high before final incorporation or 

termination (302). Mowing or grazing at bloom 

can kill the plants (125). 

In dryland areas,the optimum termination date 

for a green manure varies with moisture conditions. 

In a spring wheat>fallow rotation in Saskatchewan, 

sweetclover incorporated in mid-June of 

a dry year provided 80 percent more N the following 

spring than it did when incorporated in 

early July or mid-July—even though it yielded up 

to a third less biomass at the June date. 

Mineralization from sweetclover usually peaks 

about a year after it is killed.The potential rate of 

N release decreases as plants mature and is affected 

by soil moisture content (112). 

In this study, the differences in N release were 

consistent in years of normal precipitation, but 

were less pronounced. Little N mineralization 

occurred in the incorporation year. Nitrogen 

addition peaked in the following year, and has 

been shown to continue over seven years following 

yellow sweetclover (112). 

In northern spring wheat areas of North 

Dakota, yellow sweetclover is usually terminated 

in early June just at the onset of bloom, when it 

reaches 2 to 3 feet tall. This point is a compromise 

between cover crop gain (in 

dry matter and N) and water 

consumption. A quick kill 

from tillage or haying is more 

expensive and labor-intensive 

than chemical desiccation, 

but it stops moisture-robbing 

transpiration more quickly 

(116). Herbicides that kill sweetclover include 

2,4-D, dicamba, glyphosate and paraquat (25), 

with the latter material offering quicker desiccation 

than glyphosate (82). 

Grazing is another way to manage second-year 

sweetclover before incorporation. Start early in 

the season with a high stocking rate of cattle to 

stay ahead of rapid growth. Bloat potential is 

slightly less than with alfalfa (116). 

During its second season, 

yellow sweetclover can 

grow 8 feet tall while 

roots penetrate 5 feet deep. 


Sweetclover is a rather poor competitor in its 

establishment year, making it difficult to establish 

pure sweetclover in a field with significant weed 

pressure. 

Sweetclover residue is said to be allelopathic 

against stinkweed and green foxtail. Repeated 

mowing of yellow sweetclover that is then left to 

mature is reported to have eradicated Canada thistle. 

Letting sweetclover bloom and go to seed 

dries out soil throughout the profile,depleting the 

root reserves of weeds. 

Sweetclover weevil (Sitonia cylindricollis) is a 

major pest in some areas, destroying stands by 

defoliating newly emerged seedlings. Long rotations 

can reduce damage, an important factor for 

organic farmers who depend on sweetclover fertility 

and soil improvements. In the worst years of 

an apparent 12 to 15-year weevil cycle in his area, 

“every sweetclover plant across the countryside 

is destroyed,” according to organic farmer David 

Podoll, Fullerton, N.D. “Then the weevil population 

crashes, followed by a few years where 

they’re not a problem,then they begin to rebuild.” 

Cultural practices have not helped change the 

cycle, but planting early with a non-competitive 

nurse crop (flax or small grains) gives sweetclover 

plants the best chance to survive weevil 

foraging, Podoll says. Efforts continue on his farm 

and other locations to establish a parasitic wasp 

from a similar climate in 

Russia that will help to stabilize 

the weevil population. 

Eric and Anne Nordell of 

north-central Pennsylvania 

report that early spring plowdown 

of their overwintered 

sweetclover gives them fewer 

slug and grub problems on spring-planted crops 

than later plowdown. They prefer to have the 

legume start a cover>fallow>cover sequence on 

their certified organic farm.They overseed yellow 

sweetclover into early crops in June, let it overwinter, 

then plow it down. A slug-fighting bare 

fallow period then precedes August-planted rye 

and hairy vetch. The Nordells fit their cash 

crops around the cover crop rotation that best 


enhances soil fertility, texture and moisture and 

suppresses weeds. See Full-Year Covers Tackle 

Tough Weeds (p. 38). 

In a three-year Michigan trial of crop rotations 

to decrease economic losses to nematodes, a 

yellow sweetclover (YSC)>YSC>potato sequence 

out-yielded other combinations of rye, corn, 

Sorghum- sudangrass and alfalfa. Two years of 

clover or alfalfa followed by potatoes led to a yield 

response equivalent to application of a nematicide 

for control of premature potato vine death 

(56). Legume-supplied N coupled with an overall 

nutrient balance and enhanced cation exchange 

capacity from the cover crop are thought to be 

involved in suppressing nematode damage (20). 

Crop Systems 

In the moderately dry regions of the central and 

northern Great Plains,“green fallow”systems with 

water-efficient legumes can be substituted for 

bare-ground or stubble mulch fallow. In fallow 

years, no cash crop is planted with the intent of 

recovering soil moisture, breaking disease or 

weed cycles and maximizing yields of following 

cash crops. The retained 

residue of “brown” fallow 

lessens the erosion and evaporation 

of tillage-intensive “black 

fallow,” but “green fallow” offers 

even more benefits in terms of 

soil biological life, biodiversity, 

beneficial insect habitat, possible 

harvestable crops and alternate forages. 

Rapeseed (Brassica campestris) is a summer 

annual cash crop in the dryland West that can 

serve as a nurse crop for sweetclover. A 

Saskatchewan study of seeding rates showed optimum 

clover yield came when sweetclover was 

sown at 9 lb./A and rapeseed was sown at 4.5 

lb./A. The mixture allows an adequate stand of 

sweetclover that provides soil protection after the 

low-residue rapeseed (203). 

Sole-cropped oilseed species (rapeseed, sunflower, 

crambe and safflower) require herbicides 

for weed control. Many of these materials are 

compatible with legumes, offering a post-emergent 

weed-control option if the covers do not adequately 

suppress weeds. The covers greatly 

Sweetclover is the best 

producing warm-season 

forage legume, even 

topping alfalfa. 

reduce the erosion potential after oilseed crops, 

which leave little residue over winter (116). 

Interplanting works with tall crops. A 

Wisconsin researcher reported success drilling 

sweetclover between the rows when corn was 6 

to 12 inches tall. Overseeding sweetclover into 

sweet corn works even better due to greater light 

penetration. 

Sweetclover overseeded into sunflowers at last 

cultivation succeed about half the time, North 

Dakota trials show. Dry conditions or poor seedto-soil 

contact were the main reasons for not getting 

a stand. A heavier seeding rate or earlier 

planting will tend to increase stand. Band-seeding 

sweetclover over the row with an insecticide box 

at sunflower planting proved more successful in 

the trial. The method also permits between-row 

cultivation (116). 

Even though legume green manures in another 

North Dakota study used about 2.8 inches (rainfall 

equivalent) more water than fallow,they led to 

a 1-inch equivalent increase over fallow in soil 

water content in the top 3 inches of soil the following 

spring (9). 

One green fallow option is 

planting yellow sweetclover 

with spring barley or spring 

peas. This is challenging, however, 

because barley can be 

overly competitive while herbicide 

compatibility is a concern 

with the peas. 

Fred Kirschenmann of Windsor, N.D., controls 

spring weed flushes on his fallow after sunflowers 

with an initial shallow chisel plowing then a 

rod weeder pass or two before planting sweetclover 

with a nurse crop of buckwheat or oats (or 

millet, if there is less soil moisture). He harvests 

buckwheat, hoping for a 900 lb./A yield, then lets 

the clover grow and overwinter. In early summer, 

when he begins to see yellow blossoms, he disks 

the cover,lets it dry,then runs a wide-blade sweep 

plow just below the surface to cut apart the 

crowns. The biomass contribution of the sweetclover 

fallow builds up organic matter, he says, in 

contrast to the black-fallow route of burning up 

organic matter to release N. Preventing humus 

depletion holds back the dreaded kochia weed. 

SWEETCLOVERS 145

In higher-rainfall temperate areas,overseed vegetables 

with yellow sweetclover in early or midsummer. 

A one-row cultipacker greatly improves 

germination of overseeded legumes on the 

Nordell farm in their fresh vegetable operation 

near Trout Run, Pa. If in-row weeds are under control 

and a crop canopy is forming, the clover’s 

slow start should prevent competition with the 

crop. Heavy late-season moisture could cause 

excessive clover growth if you have no means to 

mow between the rows, the Nordells found. 

They will sometimes mix yellow sweetclover 

with white and red clover for June overseeding 

into early crops. Seeding rate is 15, 4 and 6 lb./A, 

respectively. The red and white clovers regrow 

in late summer of Year 2 after the yellow sweetclover 

has been clipped 

twice,once in late May then 

again at full-bloom in mid- 

July. 

In temperate areas you 

can overseed spring broccoli 

with HUBAM annual 

sweetclover, let the cover grow during summer, 

then till it in before planting a fall crop. 

Alternatively, you can allow it to winterkill for a 

thick, lasting mulch. 

Other Options 

First-year forage has the same palatability and 

feeding value as alfalfa, although harvest can 

reduce second-year vigor. Second-year forage is of 

lower quality and becomes less palatable as plants 

mature, but may total 2 to 3 tons per acre (91). 

Growers report seed yield of 200 to 400 lb./A 

in North Dakota. Minimize shattering of seedpods 

by swathing sweetclover when 30 to 60 percent 

of its pods are brown or black. Pollinating insects 

are required for good seed yield (141). 

Hard seed that escapes harvest will remain in 

the soil seed bank, but organic farmer Rich 

Mazour of Deweese, Neb., sees that as a plus. 

A 20- to 30-percent stand in his native grass pastures 

comes on early each spring, giving his cattle 

early grazing. Once warm-season grasses start to 

grow, they keep the clover in check. In tilled 

fields,modern sweep cultivators and residue-management 

tillage implements take care of sweetclovers 

with other tap-rooted “resident vegetation,” 

Mazour says. 


Sweetclover tolerates a wide 

range of harsh environments, 

poor soils and pests. 

Sweetclover and other deep-rooted biennial and 

perennial legumes are not suited for the most 

severely drought-prone soils, as their excessive 

soil moisture use will depress yield of subsequent 

wheat crops for years to come (128). 

When planting sweetclover after wheat harvest, 

weeds can become a problem. An organic 

farmer in northeastern Kansas reports that to kill 

cocklebur, he has to mow lower than the sweetclover 

can tolerate. Annual alfalfa can tolerate 

low mowing (161). 

After 90 days’growth in a 

North Dakota dryland 

legume comparison, a June 

planting of yellow sweetclover 

produced dry matter 

and N comparable to alfalfa 

and lespedeza (Lespedeza 

stipulacea Maxim). Subclover, fava beans (Vicia 

faba) and field peas had the best overall N-fixing 

efficiency in the dryland setting because of quick 

early season growth and good water use 

efficiency (270). 

SEED 

Cultivars. Yellow cultivars include MADRID, 

which is noted for its good vigor and production, 

and its relative resistance to fall freezes. GOLDTOP 

has excellent seedling vigor, matures two weeks 

later, provides larger yields of higher quality forage 

and has a larger seed than MADRID (302). 

Yellow common and YUKON joined GOLDTOP 

and MADRID—all high-coumarin types—as the 

highest yielding cultivars in a six-year North 

Dakota test (215). 

Leading white biennial cultivars are DENTA, 

POLARA and ARCTIC.POLARA and ARCTIC are adapted 

to very cold winters. Best for grazing are the 

lower-producing, low-coumarin cultivars DENTA 

and POLARA (white) and NORGOLD (yellow). 



WHITE CLOVER 

Trifolium repens 

Also called: Dutch White, New 

Zealand White, Ladino 

Type: long-lived perennial or winter 

annual legume 

Roles: living mulch, erosion protection, 

green manure, beneficial insect 

attraction 

Mix with: annual ryegrass, red 

clover 



summer annual 

perennial 

White clovers are a top choice for “living 

mulch” systems planted between rows 

of irrigated vegetables or trees. They 

are persistent, widely adapted perennial nitrogen 

producers with tough stems and a dense shallow 

root mass that protects soil from erosion and suppresses 

weeds. Depending on the type, plants 

grow just 6 to 12 inches tall, but thrive when 

mowed or grazed.Once established,they stand up 

well to heavy field traffic and thrive under cool, 

moist conditions and shade. 

Three types: Cultivars of white clover are 

grouped into three types by size. The lowest 

growing type (Wild White) best survives heavy 

traffic and grazing. Intermediate sizes (Dutch 

White, New Zealand White and Louisiana S-1) 

flower earlier and more profusely than the larger 

types, are more heat-tolerant and include most of 

the economically important varieties. The large 

(Ladino) types produce the most N per acre of 

any white types, and are valued for forage quality, 

especially on poorly drained soil.They are generally 

less durable, but may be two to four times 

taller than intermediate types. 

Intermediate types of white clover include 

many cultivated varieties, most originally bred 

for forage. The best of 36 varieties tested in 

north-central Mississippi for cover crop use 

were ARAN,GRASSLAND KOPU and KITAOOHA.These 

ranked high for all traits tested, including plant 

vigor, leaf area, dry matter yield, number of seedheads,lateness 

of flowering and upright stems to 

prevent soil contact. Ranking high were ANGEL 

GALLARDO, CALIFORNIA LADINO and widely used 

LOUISIANA S-1 (321). 

White clover performs best when it has plenty 

of lime, potash, calcium and phosphorus, but it 

tolerates poor conditions better than most 

clovers. Its perennial nature depends on new 

plants continually being formed by its creeping 

stolons and, if it reaches maturity, by reseeding. 

White clover is raised as a winter annual in the 

South, where drought and diseases weaken 

stands. It exhibits its perennial abilities north 

through Hardiness Zone 4. The short and intermediate 

types are low biomass producers, while 

the large ladino types popular with graziers can 

produce as much biomass as any clover species. 

BENEFITS 

Fixes N. A healthy stand of white clover can produce 

80 to 130 lb. N/A when killed the year after 

WHITE CLOVER 147

establishment. In established stands, it also may 

provide some N to growing crops when it is 

managed as a living mulch between crop rows. 

Because it contains more of its total N in its roots 

than other legumes, partial tilling is an especially 

effective way to trigger N release. The low C:N 

ratio of stems and leaves causes them to decompose 

rapidly to release N (82). 

Tolerates traffic. Wherever there’s intensive 

field traffic and adequate soil moisture, white 

clover makes a good soil covering 

that keeps alleyways green. It 

reduces compaction and dust 

while protecting wet soil against 

trauma from vehicle wheels. 

White clover converts vulnerable 

bare soil into biologically active 

soil with habitat for beneficial 

organisms above and below the 

soil surface. 

Premier living mulch. Their ability to grow in 

shade, maintain a low profile, thrive when repeatedly 

mowed and withstand field traffic makes 

intermediate and even short-stemmed white 

clovers ideal candidates for living mulch systems. 

To be effective, the mulch crop must be managed 

so it doesn’t compete with the cash crop for light, 

nutrients and moisture.White clover’s persistence 

in the face of some herbicides and minor tillage is 

used to advantage in these systems (described 

below) for vegetables, orchards and vineyards. 

Value-added forage. Grazed white clover is 

highly palatable and digestible with high crude 

protein (about 28 percent), but it poses a bloat 

risk in ruminants without careful grazing management 

practices. 

Spreading soil protector. Because each white 

clover plant extends itself by sending out root-like 

stolons at ground level, the legume spreads over 

time to cover and protect more soil surface. 

Dropped leaves and clipped biomass effectively 

mulch stolons, encouraging new plants to take 

root each season.Reseeding increases the number 

of new plants if you allow blossoms to mature. 

Tough, low-growing 

and shade tolerant, 

this perennial is often 

used as a living mulch 

in vegetable systems. 

Fits long, cool springs. In selecting a fall-seeded 

N-producer, consider white clover in areas 

with extended cool springs. MERIT ladino clover 

was the most efficient of eight major legumes 

evaluated in a Nebraska greenhouse for N2 fixed 

per unit of water at 50 F. Ladino, hairy vetch and 

fava beans (Vicia faba) were the only legumes 

shown to fix more than 50 percent of their total 

N output at the 50 F temperature. Fava bean’s N 

fixation rate declined during the period 42 to 105 

days after planting as ambient temperature 

increased, while ladino’s fixation 

rate increased at each of 

four sample dates (273). 

Overseeded companion crop. 

Whether frostseeded in early 

spring into standing grain, 

broadcast over vegetables in 

late spring or into sweet corn in 

early summer, white clover germinates 

and establishes well under the primary 

crop. It grows slowly while shaded as it develops 

its root system, then grows rapidly when it 

receives more light. 

MANAGEMENT 


Widely adapted. White clover can tolerate wet 

soil—even short flooding—and short dry spells, 

and survives on medium to acid soils down to pH 

5.5. It volunteers on a wider range of soils than 

most legumes, but grows better in clay and loam 

soils than on sandy soils (91). Ladino prefers 

sandy loam or medium loam soils. 

Use higher seeding rates (5 to 9 lb./A drilled, 7 

to 14 lb./A broadcast) when you overseed in 

adverse situations caused by drought, crop 

residue or vegetative competition. Drill 4 to 6 

lb./A when mixing white clover with other 

legumes or grasses to reduce competition for 

light, moisture and nutrients. 

Frostseeding of small-seeded clovers (such as 

alsike and white) should be done early in the 

morning when frost is still in the soil. Later in the 

day,when soil is slippery,stand establishment will 

be poor.Frostseed early enough in spring to allow 


for several freeze-thaw cycles. Make sure warmsoil 

seedings are established before summer 

droughts hit (302). 

Late-summer seeding must be early enough to 

give white clover time to become well established,because 

fall freezing and thawing can readily 

heave the small, shallow-rooted plants. Seeding 

about 40 days before the first killing frost is usually 

enough time. Best conditions for summer 

establishment are humid, cool and shaded (91, 

302). Legumes suffer less root damage from frost 

heaving when they are planted with a grass (82). 

In warmer regions of the U.S. (Zone 8 and 

warmer), every seeding should be inoculated. N- 

fixing bacteria persist longer in cooler soils, with 

even volunteer wild white clover leaving enough 

behind for up to three years (91). 

Mowing no lower than 2 to 3 inches will keep 

white clover healthy. To safely overwinter white 

clover, leave 3 to 4 inches (6 to 8 inches for taller 

types) to prevent frost damage. 

Killing 

Thorough uprooting and incorporation by chisel 

or moldboard plowing, field cultivating, undercutting 

or rotary tilling, or—in spring—use of a suitable 

herbicide (glyphosate, for example) will 

result in good to excellent kill of white clover. 

Extremely close mowing and partial tillage that 

leaves any roots undisturbed will suppress, but 

not kill, white clover. 


Prized by bees. Bees work white clover blossoms 

for both nectar and pollen. Select insectmanagement 

measures that minimize negative 

impact on bees and other pollinators. 

Insect/disease risks. White clovers are fairly tolerant 

of nematodes and leaf diseases, but are susceptible 

to root and stolon rots. Leading insect 

pests are the potato leafhopper (Empoasca fabae), 

meadow spittlebug (Philaenis spumarius), clover 

leaf weevil (Hypera punctata), alfalfa weevil 

(Hypera postica) and Lygus bug (Lygus spp.). 

If not cut or grazed to stimulate new growth, 

the buildup of vegetation on aged stolons and 

stems creates a susceptibility to disease and insect 

WHITE CLOVER (Trifolium repens— 

intermediate type) 

problems.Protect against pest problems by selecting 

resistant cultivars, rotating crops, maintaining 

soil fertility and employing proper cutting schedules 

(302). 

Crop Systems 

Living mulch systems. As a living mulch, white 

clover gives benefits above and below ground 

while it grows between rows of cash crops, primarily 

in vegetables, orchards and vineyards. 

Living mulch has not proved effective in agronomic 

crops to this point. To receive the multiple 

benefits, manage the covers carefully throughout 

early crop growth—to keep them from competing 

with the main crop for light, nutrients, and 

especially moisture—while not killing them. 

Several methods can do that effectively. 

Hand mowing/in-row mulch. Farmer Alan 

Matthews finds that a self-propelled 30-inch 

rotary mower controls a clover mix between 

green pepper rows in a quarter-acre field.He uses 

40-foot wide, contour strip fields and the living 

mulch to help prevent erosion on sloping land 

near Pittsburgh, Pa. In his 1996 SARE on-farm 

research, he logged $500 more net profit per acre 

on his living mulch peppers than on his conventionally 

produced peppers (207, 208). 

Matthews mulches the transplants with hay, 12 

inches on each side of the row.He hand-seeds the 


WHITE CLOVER 149

cover mix at a heavy 30 lb./A between the rows. 

The mix is 50 percent white Dutch clover,30 percent 

berseem clover, and 20 percent HUIA white 

clover, which is a bit taller than the white Dutch. 

He mows the field in fall,then broadcasts medium 

red clover early the next spring to establish a hay 

field and replace the berseem, which is not winterhardy 

(207, 208). 

New Zealand white clover provided good 

weed control for winter squash in the wetter of 

two years in a New York 

trial. It was used in an 

experimental non-chemical 

system relying on over-therow 

compost for in-row 

weed control. Plants were 

seeded into tilled strips 16 

inches wide spaced 4 feet apart. Poor seed establishment 

and lagging clover growth in the drier 

year created weed problems, especially with 

perennial competitors.The living mulch/compost 

system yielded less than a conventionally tilled 

and fertilized control both years, due in part to 

delayed crop development from the in-row compost 

(226). 

The research showed that in dry years,mowing 

alone won’t suppress a living mulch enough to 

keep it from competing for soil moisture with 

crops in 16-inch rows.Further,weeds can be even 

more competitive than the clover for water during 

these dry times (226). 

A California study showed that frequent mowing 

can work with careful management. A white clover 

cover reduced levels of cabbage aphids in harvested 

broccoli heads compared with clean-cultivated 

broccoli. The clover-mulched plants, in strip-tilled 

rows 4 inches wide,had yield and size comparable 

to clean cultivated rows. However, only intensive 

irrigation and mowing prevented moisture competition. 

To be profitable commercially, the system 

would require irrigation or a less thirsty legume, as 

well as field-scale equipment able to mow between 

several rows in a single pass (67). 

Chemical suppression is difficult. An application 

rate that sets back the clover sufficiently 

one year may be too harsh (killing the clover) or 

not suppressive the next year due to moisture, 

temperature or soil conditions. 

Healthy stands can produce 

80 to 130 lb. N/A when killed 

the year after establishment. 

Partial rotary tillage. In a New York evaluation 

of mechanical suppression, sweet corn planting 

strips 20 inches wide were rotary tilled June 2 

into white clover. While mowing (even five times) 

didn’t sufficiently suppress clover, partial rotary 

tilling at two weeks after emergence worked well. 

A strip of clover allowed to pass between the 

tines led to ample clover regrowth.A surge of N 

within a month of tilling aided the growing corn. 

The loss of root and nodule tissue following stress 

from tillage or herbicide 

shock seems to release N 

from the clover. Leaf smut 

caused less problem on the 

living-mulch corn than on 

the clean-cultivated check 

plot (133). 

Crop shading. Sweet corn shading can hold 

white clover in check when corn is planted in 15- 

inch rows and about 15 inches apart within the 

row. This spacing yielded higher corn growth 

rates, more marketable ears per plant and higher 

crop yields than conventional plots without 

clover in an Oregon study. Corn was planted into 

tilled strips 4 to 6 inches wide about the same 

time the clover was chemically suppressed. 

Adapted row-harvesting equipment and handpicking 

would be needed to make the spacing 

practical (105). 

Unsuppressed white Dutch clover established at 

asparagus planting controlled weeds and provided 

N over time to the asparagus in a Wisconsin study, 

but reduced yield significantly. Establishing the 

clover in the second year or third year of an asparagus 

planting would be more effective (251). 

Other Options 

Seed crop should be harvested when most seed 

heads are light brown, about 25 to 30 days after 

full bloom. 

Intermediate types of white clover add protein 

and longevity to permanent grass pastures without 

legumes.Taller ladino types can be grazed or 

harvested. Living mulch fields can be overseeded 

with grasses or other legumes to rotate into pasture 

after vegetable crops, providing IPM options 

and economic flexibility. 



• White clover is less tolerant of basic soils 

above pH 7 than are other clovers. 

• In a Wisconsin comparison, ladino clover biomass 

was similar to mammoth red clover 

when spring-seeded (330). 

• White clover stores up to 45 percent of its N 

contribution in its roots, more than any other 

major legume cover crop. 

• Ladino and alsike are the best hay-type 

legumes on poorly drained soils. 

• Spring growth of fall-seeded white clover 

begins in mid-May in the Midwest, about the 

same time as alfalfa. 


WOOLLYPOD VETCH 

Vicia villosa ssp. dasycarpa 

Also called: LANA vetch 

Cycle: cool-season annual 

Type: legume 

Roles: N source, weed suppressor, 

erosion preventer, add organic 

matter, attract bees 

Mix with: other legumes, grasses 



area of primary utility 

viable during mild, moist seasons 

Specialty vetches such as woollypod and purple 

vetch (Vicia benghalensis) are fastergrowing 

alternatives to hairy vetch (Vicia 

villosa) in Hardiness Zone 7 and warmer. 

Requiring little or no irrigation as a winter cover 

in these areas,they provide dependable,abundant 

N and organic matter, as well as excellent weed 

suppression. 

Many growers of high-value crops in California 

rely on one or more vetch species as a self-reseeding 

cover crop, beneficial insect habitat and 

mulch. They can mow the vetch during winter 

and in late spring after it reseeds. 

Some vineyard managers seed LANA woollypod 

vetch each year with oats or as part of a legume 

mix—common vetch, subterranean clover, a 

medic and LANA, for example. They plant the mix 

in alternate alleyways to save on seeding costs 

and reduce moisture competition, while ensuring 

sufficient cover that they can mow or disk. LANA’s 

climbing tendency (even more so than purple or 

common vetch) and abundant biomass can 

become problems in vineyards and young 

orchards,but can be readily managed with regular 

monitoring and timely mowing. 

In Zone 5 and colder and parts of Zone 6,woollypod 

vetch can serve as a winterkilled mulch— 

or as a quick, easy-to-mow spring cover—for 

weed control and N addition to vegetable transplants. 

It’s a good choice as an overwintering 

cover before or after tomato crops in Zone 6 

and warmer. A study in California showed that 

WHOOLLYPOD VETCH 151

LANA provided the most N and suppressed the 

most weeds during two consecutive but distinctly 

different growing seasons, compared with purple 

vetch and other legume mixtures (342, 343). 

BENEFITS 

N Source. A first-year, overwintering stand of 

woollypod vetch easily will provide more than 

100 pounds of N per acre in any system when 

allowed to put on spring growth. The popular 

LANA cultivar starts fixing N in as little as one week 

after emergence. 

LANA can contribute as much as 300 pounds of 

N its first year or two, given adequate moisture 

and warm spring growing conditions (219, 324). 

Fall-planted LANA incorporated before a corn crop 

can provide a yield response equivalent to 200 lb. 

N/A, a California study showed (219). Similar 

results have been seen in tomato research in 

California (324). In western Oregon, a yield 

response equivalent to 70 lb. N/A for sweet corn 

has been observed (87). 

Plenty of soil-building organic matter. 

Woollypod typically produces more dry matter 

than any other vetch. LANA shows better early 

growth than other vetches, even during cool late 

fall and winter weather in 

Zone 7 and warmer. LANA 

shows explosive growth in 

early spring in the Pacific 

Northwest (87) and in late 

winter and early spring in 

California when moisture is 

adequate. It can provide up to 8,000 lb. DM/A, 

which breaks down quickly and improves soil 

structure (44, 219, 324). 

Frost protectant. Some orchard growers have 

found that keeping a thick floor cover before the 

blossom stage can help prolong a perennial 

crop’s dormant period by up to 10 days in 

spring.“This reduces the risk of early frost damage 

(to the blossoms, by delaying blossoming) 

and lengthens the blossoming period of my 

almond trees,” notes almond grower Glenn 

Anderson, Hilmar, Calif. 

Smother crop. Woollypod’s dense spring 

growth smothers weeds and also provides some 

allelopathic benefits. Of 32 cover crops in a replicated 

study at a California vineyard, only LANA 

completely suppressed biomass production of 

the dominant winter annual weeds such as chickweed, 

shepherd’s purse, rattail fescue and annual 

ryegrass (351). 

Beneficial habitat. Woollypod vetch attracts 

many pollinators and beneficial insects. In some 

orchards, these beneficials move up into the tree 

canopy by late spring, so you can mow the floor 

cover after it reseeds and not worry about loss of 

beneficial habitat (142). 

MANAGEMENT 

Woollypod vetch is often 

used in mixes in California 

orchards and vineyards. 


Woollypod does well on many soil types—even 

poor, sandy soil—and tolerates moderately acidic 

to moderately alkaline conditions. It’s welladapted 

to most orchard and vineyard soils in 


It establishes best in recently tilled, nutrientdeficient 

fields (5). Tillage helps enhance the 

reseeding capability of vetches (44). LANA woollypod 

vetch hasn’t done as well in some no-till systems 

as it was expected to. 

Given adequate moisture, 

however, broadcasting LANA 

even at low to moderate 

rates—and with light incorporation—can 

give satisfactory 

results from fall 

seedings,especially if the stand is allowed to grow 

through mid-spring. If your goal is to shade out 

competition quickly, however, broadcast at medium 

to high rates and incorporate lightly. 

You might not recognize the emerging plant 

without its characteristic multiple leaflets, says 

Glenn Anderson.“You should spot it within two 

weeks of planting, three at the latest, depending 

on temperature and soil conditions. Even at 6 

inches,it’ll still look spindly.It won’t really leaf out 

until late winter and early spring, when more 

aggressive growth kicks in.” That may continue 

until maturity in mid- to late May. 


Fall planting. Most growers seed at low to medium 

rates, regardless of seeding method. If drilling, 

1 

/2 to 1 inch deep is best, although up to 2 inches 

will work for early seedings. If broadcasting, follow 

with a cultipacker or a shallow pass of a 

spike-toothed harrow. 

Seedbed preparation is crucial for establishing 

a healthy cover crop stand in vineyards.California 

viticulturist and consultant Ron Bartolucci recommends 

making two passes with a disk to kill 

existing vegetation and provide some soil disturbance. 

He cautions against using a rotary tiller, 

which can pulverize the soil and reduce its waterholding 

capacity (167). 

Bartolucci prefers to drill rather than broadcast 

cover crops, saving on seed costs and ensuring 

seed-to-soil contact. He recommends the economical, 

alternate row planting that also ensures 

easy access for pruning grape vines. 

Don’t wait too long in fall to seed woollypod 

vetch in Zone 7 and warmer, however. If you 

wait until the soil starts getting cold, in mid- 

October in Oregon and early November in parts 

of central California,germination will be poor and 

the stand disappointing. Seed too early, though, 

and you miss the early moisture benefit of the 

Central Valley’s fog season (5) and will need to 

irrigate more before the rainy season (168). 

Regardless of your planting method,seed woollypod 

vetch into moist soil or irrigate immediately 

after seeding to help germination (219). If 

irrigation is an option but you want to conserve 

water costs,try seeding just before a storm is forecast, 

then irrigate if the rain misses you. 

Spring planting. Planted in early spring, woollypod 

vetch can provide plowdown N by Memorial 

Day for a summer annual cash crop in the 

Northeast (300). 

WOOLLYPOD VETCH (Vicia villosa ssp. 

dasycarpa) 

Mowing & Managing 

Woollypod vetch can survive freezing conditions 

for days, but severe cold can markedly reduce its 

dry matter and N production (170, 219). 

In most cases, main challenges for an established 

woollypod vetch stand include managing 

its abundant growth and viny tendrils and ensuring 

adequate moisture for your primary crop. In 

wet environments such as western Oregon, however, 

LANA vetch can retard spring soil drying and 

seedbed preparation for summer crops (87). 

Woollypod responds well to mowing,as long as 

you keep the stand at least 5 inches tall and avoid 

mowing during the two-month period just before 

it reseeds. “I can mow as late as mid-March and 

still see good reseeding,” says Glenn Anderson, an 

organic almond grower in California’s Central 

Valley. “After that, I may mow if I want to prevent 

some frost damage, but I know I’ll lose some of 

the vetch through reduced reseeding.” 

Anderson usually mows the floor cover once or 

twice before mid-March and after it reseeds. He 

cuts in the direction of prevailing winds—which 

can be on a diagonal to his tree rows—to facilitate 

air movement throughout the orchard, especially 

when he anticipates moist air heading his way. 

In vineyards,“high chopping” legume mixes to 

a 12-inch height can help keep them from trellising 

over vine cordons. In vineyards without 

sprinklers for frost protection, some growers 

incorporate legume mixes in spring, before the 

soil becomes too dry for disking. Where sprin- 

Elayne Sears 

WOOLLYPOD VETCH 153

klers are used, the covers might be allowed to 

grow for a longer period and provide additional 

N. Timing is important when disking, however, 

as you don’t want to make equipment access 

difficult or compact soil during wet spring 

conditions (167). 

Given the high dry matter production from 

woollypod vetch when it’s allowed to grow at 

least until late March, two or three diskings or 

mowings will encourage rapid decomposition. 

Power spaders can reduce soil compaction when 

incorporating vetches in spring conditions, compared 

with heavier disk harrows (350). 

Moisture concerns. Many orchard and vineyard 

growers find it helpful to drip irrigate tree or vine 

rows if they are growing an aggressive cover crop 

such as LANA between the rows 

for the first time. In California 

vineyards where irrigation isn’t 

used, a few growers report that 

vines seem to lose vigor faster 

when grown with cover crops. 

Others haven’t observed this 

effect.After a few years of growing 

leguminous covers, many find that their soil is 

holding moisture better and they need less water 

to make the system work. 

Reseeding concerns. Vetch mixtures often fail 

to reseed effectively, especially if they have been 

mowed at the wrong time or soil fertility is high. 

Some vineyard managers expect low persistence 

and reseed a vetch mix in alternate rows every 

fall, or reseed spotty patches. 

Regardless of mowing regime, LANA’s persistence 

as a self-reseeding cover diminishes over 

time, and other resident vegetation starts to take 

over. That’s a sign that the cover’s water-holding, 

fertility- and tilth-enhancing benefits have kicked 

in, says Glenn Anderson. 

It’s natural to expect a change in the resident 

vegetation over time, observes Anderson. After a 

few years of reseeding itself—and providing 

abundant dry matter and nitrogen—the LANA he 

had clear seeded at low rates between orchard 

rows on half his acreage eventually diminished to 

LANA woollypod vetch 

shows explosive growth 

in early spring in the 

Pacific Northwest. 

about 10 percent of the resident vegetation, he 

notes. Subclovers and other legumes he introduced 

have become more prominent. Those 

legumes may have better self-reseeding capability 

than LANA, other growers note (168). 


Woollypod vetch outcompetes weeds and will 

quickly resolve most weed problems if seeded at 

high rates. Woollypod also provides some 

allelopathic benefits. A root exudate can reduce 

growth in some young grasses, lettuces and peas, 

however. 

Hard seed carryover can cause LANA to become 

a weed in subsequent cash crops and vineyards, 

however (55). Its strong climbing ability can 

cover grape vines or entwine sprinklers. In 

orchards,it’s fairly easy to cut or 

pull Lana vines out of the 

canopy of young trees. Mowing 

or “high chopping” may be 

needed, especially in vineyards, 

even though this can reduce 

LANA’s reseeding rate. 

Insects pests aren’t a major 

problem with woollypod vetch, in part because it 

attracts lady beetles, lacewings, minute pirate 

bugs and other beneficials insects that help keep 

pests in check. 

LANA can be a host of Sclerotinia minor, a soilborne 

pathogen that causes lettuce drop, a fungal 

disease affecting lettuce, basil and cauliflower 

crops. In a California study involving cover crops 

that were deliberately infected with S. minor, the 

pathogen levels were associated with higher lettuce 

drop incidence the summer after Lana had 

been incorporated, but wasn’t as problematic the 

following year. Woollypod vetch probably isn’t a 

good choice if you’re growing crops susceptible 

to this pathogen. 

Other Options 

Seed. Woollypod vetch is a prolific seed 

producer, but its pods are prone to shattering. 

You can increase seed harvest by raking the 

field (without mowing, if possible) to gather 

the crop into windrows for curing, before 


combining with a belt-type rubber pickup 

attachment (350). 

Forage. Like most vetches, LANA is a somewhat 

bitter yet palatable forage when green, and the 

palatability increases with dryness (350). It is a 

nutritious forage for rangeland use (350). 

For hay, it is best cut in full bloom.The leaves 

dry rapidly and swaths can be gathered within a 

day or two (350). 


• Woollypod has slightly smaller flowers than 

hairy vetch, and its seeds are more oval than 

the nearly round seeds of hairy vetch. LANA 

also has a higher proportion of hard seed than 

hairy vetch (351). 

•LANA shows more early growth than common 

vetch, although both increase their biomass 

dramatically by midspring (168). 

•LANA and purple vetch are more cold-sensitive 

than common vetch or hairy vetch. Once established, 

LANA can tolerate early frosts for a few 

days (especially if the temperature doesn’t fluctuate 

widely or with some snow cover) and is 

hardier than purple vetch, which is more susceptible 

to early spring dieback (114). 

•LANA flowers about three weeks earlier than 

purple vetch and has a better chance of setting 

seed in dryland conditions (219). 

•LANA and LANA mixes suppress weeds better 

than purple vetch (114). 

Seed sources. Widely available in the West, 

including Ampac, Harmony, Lohse Mill and 

Peaceful Valley. See Seed Suppliers (p. 166). 

WOOLLYPOD VETCH 155

APPENDIX A 

TESTING COVER CROPS ON YOUR FARM 


To find your best cover crops, you needn’t 

become Dr. Science or devote your life to 

research.It’s not hard to set up valid,on-farm tests 

and make observations. Follow these steps: 

A. Narrow your options. Aim for a limited-scale 

trial of just two to five species or mixtures. You 

can test the best one or two in a larger trial the 

next year. 

Unsure of the niche Start with small plots separated 

from cropped fields and plant over a range 

of dates, under optimal soil and weather conditions. 

If you’re sure of the niche and have just two or 

three covers to try, put the trial right in your 

cropped fields, using a similar seedbed preparation. 

This method provides rapid feedback on 

how the cover crops fit into your cropping system. 

Keep in mind management-related variables 

could cause subpar results for an otherwise adequate 

cover. 

B. Order small seed amounts. Many companies 

provide 1- to 10-pound bags if you give them 

advance notice. If 50-pound bags are the only 

option, arrange to share it with other growers. 

Don’t eliminate a species just because seed 

price seems high. If it works well, it could trim 

other costs. You could consider growing your 

own seed eventually, and perhaps even selling it 

locally. 

Be sure to obtain appropriate inoculants if 

you’ll be testing legumes, which require speciesspecific 

rhizobial bacteria so the cover can capture 

and “fix”N efficiently. See Nodulation: Match 

Inoculant to Maximize N (p. 92). 

C. Determine plot sizes. Keep them small 

enough to manage, yet large enough to yield adequate 

and reliable data. Plots a few rows wide by 

50 to 100 feet could suffice if you grow vegetables 

for market. If you have 10 or more acres, quarteror 

half-acre plots may be feasible,especially if others 

in your area use similar species. 

If you use field-scale machinery, establish fieldlength 

plots. For row crops, use plots at least four 

rows wide, or your equipment width. Keep in 

mind the subsequent crop’s management. 

D. Design an objective trial. Plots need to be as 

uniform as possible, randomly selected for 

each option you’re testing, and replicated (at 

least two or three plots for each option). 

If parts of the field have major differences 

(such as poorer drainage or weedy spots), put 

blocks of plots together so each treatment has 

equal representation in each field part, or avoid 

those areas for your trial. 

Label each plot and make a map of the trial area. 

E. Be timely. Regard the trial as highly as 

any other crop. Do as much or as little field 

preparation as you would for whole fields, and at 

an appropriate time. 

If possible, plant on two or more dates at least 

two weeks apart. In general, seed winter annuals 

at least six weeks before a killing frost.Wheat and 

rye can be planted later,although that will reduce 

the N-scavenging significantly. 

F. Plant carefully. If seeding large plots with 

tractor-mounted equipment, calibrate your seeding 

equipment for each cover. This can prevent 

failures or performance differences due to incorrect 

seeding rates. Keep a permanent record of 

drill settings for future reference. 

A hand-crank or rotary spin seeder works well 

for small plots getting less than five pounds of 

seed.Weigh seed for each plot into a separate container. 

1 lb./A is about equivalent to 1 gram/100 

sq. ft., and 1 pound equals 454 grams. 

Put half the seed in the seeder and seed 

smoothly as you walk the length of the field and 

back, with a little overlap in the spread pattern. 


Then seed the remainder while walking in perpendicular 

directions so you crisscross the plot in 

a gridlike pattern. 

If broadcasting by hand, use a similar distribution 

pattern.With small seed, mix in sand or fresh 

cat litter to avoid seeding too much at a time. 

G. Collect data. Start a trial notebook or binder 

for data and observations. 

Management information could include: 

• field location 

• field history (crops, herbicides, amendments, 

unusual circumstances, etc.) 

• plot dimensions 

• field preparation and seeding method 

• planting date and weather conditions 

• rainfall after planting 

• timing and method of killing the cover crop 

• general comments. 

Growth data for each plot might include: 

• germination rating (excellent, OK, poor, etc.), 

seven to 14 days after seeding 

• early growth or vigor rating, a month after 

establishment 

• periodic height and ground cover estimates, 

before killing or mowing 

• periodic weed assessments 

• a biomass or yield rating 

Also rate residue before planting the next crop. 

Rate survival of winter annuals in early spring as 

they break dormancy and begin to grow. If you 

plan to mow-kill an annual, log an approximate 

flowering date. Regrowth could occur if most of 

the crop is still vegetative. 

Rate overall weather and record dates such as 

first frost. Note anything you think has a bearing 

on the outcome, such as weed infestations. 

If time allows, try killing the cover crops and 

continuing your expected rotation, at least on a 

small scale.You might need hand tools or a lawn 

mower. Use field markers to identify plots. 

H. Choose the best species for the whole 

farm system. Not sure which covers did best 

Whatever you found, don’t be satisfied with only 

a single year’s results. Weather and management 

will vary over time. 

Assess performance by asking some of the 

questions you answered about the cover niche 

(see Selecting the Best Cover Crops for your 

Farm, p. 12). Also ask if a cover: 

• was easy to establish and manage 

• performed its primary function well 

• avoided competing excessively with the primary 

crop 

• seemed versatile 

• is likely to do well under different conditions 

• fits your equipment and labor constraints 

• provides options that could make it even 

more affordable 

In year two, expand the scale. Test your bestperforming 

cover as well as a runner-up. With 

field crops, try one-acre plots; stick with smaller 

plots for high-value crops. Also try any options 

that might improve the cover stand or its benefits. 

Entries for the major cover crops in this book 

include some management tips that can help. 

Record your observations faithfully. 

I. Fine-tune and be creative. Odds are, you 

won’t be completely satisfied with one or more 

details of your “best” cover. You might need to 

sacrifice some potential benefits to make a 

cover work better in your farm system. For 

example, killing a cover earlier than you’d like 

will reduce the amount of biomass or N it 

provides, but could ensure you plant summer 

crops on time. 

In most cases, fine-tuning your management 

also makes it more affordable.Lowering a seeding 

rate or shifting the seeding date also could reduce 

the tillage needed. Narrower rows might hinder 

establishment of an overseeded legume but 

reduce weeds and bump up the cash crop yield. 

Finding a regionally adapted variety of a given 

species could simplify management—but also 

might have you looking around for a better cash 

crop variety. 

Don’t expect all of a cover’s benefits to show 

up in yearly economic analyses.Some benefits are 

hard to assess in dollars. 

When talking to other farmers, seed suppliers 

and agricultural experts, tell them about your 

cover cropping experiences and ask for suggestions 

and ideas. Your best covers may seem 

TESTING COVER CROPS 157

unbeatable. But there could be an up-and-coming 

species or management technique you 

haven’t thought of testing. See Up-and-Coming 

Cover Crops (p. 158) for a few examples. 

Overwhelmed You needn’t be. Initiative and 

common sense—traits you already rely on—are 

fundamental to any on-farm testing program. As 

a grower, you already test varieties, planting 

dates and other management practices every 

year.This section offers enough tips to start testing 

cover crops. 

You also can collaborate with others in your 

region to pool resources and share findings. 

There’s a good chance others in your area could 

benefit from your cover cropping wisdom! 

[Adapted from Northeast Cover Crop 

Handbook by Marianne Sarrantonio, Rodale 

Institute, 1994.] 

APPENDIX B 

UP-AND-COMING COVER CROPS 

We chose the major cover crops in this book for 

their range of benefits, reliability, availability and 

wide adaptability. They’re not the only cover 

crops to choose from, of course. Here are a few 

others you might want to consider,either for their 

regional appeal or because they show strong 

potential once seed becomes readily available. 

Balansa clover 

Identified as a promising new cover crop in 

Mississippi research, balansa clover (Trifolium 

balansae) is a small-seeded annual legume with 

superior reseeding potential compared with 

other legumes, including crimson clover. 

Well-adapted to a wide range of soil types, balansa 

performs particularly well on silty clay soil 

with a pH of about 6.5. It does not do well on 

highly alkaline soils (18). It appears to be hardy 

throughout Zone 7A and is considered marginal 

in Zone 6B. 

Balansa clover seed is quite small, so the seeding 

rate is only 10 lb./A. The seed is expensive 

and not widely available, however. It is produced 

commercially only in Australia at this time.Balansa 

clover requires a relatively rare inoculant, designated 

“Trifolium Special #2” by Liphatech, Inc., 

manufacturer of “Nitragin” brand inoculants. (See 

Appendix D, Seed Suppliers, p. 166, for contact 

information for Liphatech, Inc. and for Kamprath 

Seed Co., which imports balansa seed). 

PARADANA is the cultivar that has been tested in 

the U.S. It was released in 1985 by the South 

Australia Department of Agriculture. A newer 

cultivar, BOLTA, was tested in California and Texas 

in 1997. 

While PARADANA seed matures slightly earlier 

than crimson clover, it often does not produce as 

much biomass. But PARADANA can reseed for several 

years, due to its relatively high amount of hard 

seed. It has volunteered back for four years following 

maturation of a seed crop in 1993 in 

Senatobia,Miss.,and has reseeded successfully for 

at least two years in no-till systems at several other 

locations in Alabama, Georgia and Mississippi. 

Neither TIBBEE nor AU ROBIN crimson clover 

reseeded for more than one year at any location in 

those tests. It’s too soon to say how well balansa 

clover reseeds after tillage, but the small seeded 

clover probably can’t stand being buried too 

deeply. 

Balansa is a bit less likely than crimson clovers 

to host root-knot nematodes (Meloidogyne incognita,race 

3).In research by Gary Windham,USDA- 

ARS, Starkville, Miss., balansa had egg mass index 

scores between 2.3 and 2.9 on a scale from 1 to 

5. For comparison, a very resistant white clover 

being readied for release has a 1.5 score, most 

crimson clovers score between 3 and 3.5 and 

very susceptible crops like REGAL white clover 

score a 5. 

Balansa was screened at several locations in a 

range of soil types and climatic zones varying 

from the Gulf Coast to northern Tennessee, and 

from Georgia to western Arkansas.Since the initial 


screening, a number of farmers have been evaluating 

balansa in trials covering an even wider geographic 

area. 

For further information, contact: 

Seth Dabney 

USDA-ARS National Sedimentation Lab. 

P.O. Box 1157 

Oxford, MS 38655-2900 

(662) 232-2975; dabney@sedlab.olemiss.edu 

Bell bean (Vicia faba) 

Other common names: fava bean, faba bean, 

small-seeded horse bean. 

Type: Winter annual or spring annual legume. 

Description: Stems coarse, upright; leaves compound, 

usually with six broad leaflets and no tendrils; 

dark purple extrafloral nectary on lower 

surface of stipule; flowers large, white, with dark 

purple blotches;pods large,cylindrical,containing 

six to eight seeds. 

Bell bean is a true vetch,but differs greatly from 

other vetches with its strong, upright growth. It 

also has a relatively shallow, thick taproot, which 

may be useful for opening up heavy soils. Bell 

bean often is used in mixtures with vetches, peas 

and/or cereals. Because of its height and because 

it does not tolerate close mowing, it often is omitted 

from mixtures in frost-prone areas. It is best 

adapted to Hardiness Zones 8 and 9. 

Bell bean is frequently infested by the pea-bean 

aphid, which seldom affects its use as a cover 

crop. The aphid, which does not attack grapes, 

and the presence of extrafloral nectaries, may 

attract beneficial insects into vineyards. However, 

their effects on insect and mite management have 

not been tested. 

Bell bean is more susceptible to frost damage 

than other vetches. It is very similar in growth to 

broad bean (also known as Windsor or horse 

bean), which has a much larger, flat seed. The 

smaller seed size of bell bean makes it more economical 

to sow. 

Bell beans grow quickly throughout the winter 

in California, add N—although less than other 

vetches—and provide a tall structure to support 

twining vetches and peas. Bell beans do not 

spread like vetches and they have no hard seed. 

They are easily incorporated into the soil. 

Estimated amount of N fixed may range from 50- 

200 lb/acre, but bell bean is regarded as a low 

nitrogen fixer in southern California. In six weeks 

of growth,bell bean may fix up to 100 lb/acre and 

a total of up to 150 lb/acre on fertile soils. 

Seed 1 to 3 inches deep at 80-200 lb./A. Faba 

bean can grow on a wide range of soils, from 

loams to clays, and under a variety of drainage 

conditions.It does not tolerate saturated soils,and 

extended drought, especially at flowering, 

reduces seed production drastically. 

Bell beans are not drought tolerant. They are 

easier to control than other vetches.Bell beans do 

not tolerate close mowing. 

—Chuck Ingels 

University of California Extension 

4145 Branch Center Rd. 

Sacramento, CA 95827-3898 

(916) 875-6913; FAX: (916) 875-6233 

caingels@ucdavis.edu 

Black oats 

Black oats (Avena strigosa) is the No. 1 cover 

crop on millions of acres of conservation-tilled 

soybeans in southern Brazil. In the temperate 

farming regions of southern South America, black 

oats owes its popularity to a number of factors. It 

is very resistant to rusts and produces large 

amounts of biomass, similar to rye. It has exceptional 

allelopathic activity for weed control. It is 

easy to kill mechanically and cycles nitrogen better 

than rye. 

Black oats breaks disease cycles for wheat and 

soybeans and is resistant (some research claims 

even suppressive) to root-knot nematodes. On 

top of this, it is also a good forage. It is not cold 

tolerant. 

One cultivar, IAPAR-61, a public release developed 

by the Paraná State Agricultural Research 

Service, has been investigated by USDA-ARS and 

was grown in 1997 in Alabama and Georgia for 

commercial seed production. Its use likely will be 

restricted to the lower southern Coastal Plain 

(Zones 8b, 9 and 10). Seed should be available 

commercially in limited amounts in 1998. 

—D.W. Reeves (see p. 161) 

UP-AND-COMING COVER CROPS 159

Foxtail (German) millet 

Foxtail millet (Setaria italica) has a variety of 

common names. Most literature refers to it as foxtail 

millet due to its similarity to other members of 

the Setaria genus (several species of weedy foxtails). 

Other common names include German millet, 

Hungarian millet and Italian millet. Compared 

to the weedy species of foxtail, this millet has a 

much larger seed head, larger golden-colored 

seed, bigger plants and a higher seed yield. This 

plant was used for centuries in China as an important 

food grain. The crop has been grown as a 

food grain, forage and occasionally for birdseed 

production. The main use in the U.S. has been for 

forage production, primarily in the Great Plains. 

Foxtail millet is a warm season crop, and will 

not overwinter. Its best use as a cover crop would 

be following spring-harvested vegetables in areas 

otherwise left fallow for a summer, or in southern 

regions as a cover crop planted in mid-summer. 

Although foxtail millet is a relatively short season 

crop (90 to 100 days in the lower Midwest), it 

must be planted in the first half of the summer to 

maximize biomass production. If planted late, 

such as mid-July through August,the plants will be 

much shorter in stature and less vigorous. 

The competitive advantage of foxtail millet lies 

in its drought tolerance, relatively quick growth 

and its status as a warm season annual that can be 

drilled in narrow rows.The crop is relatively easy 

to establish, like oats or wheat, and establishes 

best when drilled rather than broadcast.With adequate 

rainfall, the crop will reach 3 to 4 feet tall 

within about 50 to 60 days, but will be shorter 

under limited moisture conditions or when planted 

late. Foxtail millet fits a mid-summer niche not 

filled by cool season grains such as wheat, oats 

and rye. It provides more biomass in a short period 

than many warm season grasses, though perhaps 

not as much as sorghum or pearl millet. 

Compared to those two crops however, foxtail 

millet may provide better erosion control because 

it can be drilled in narrow rows. 

Foxtail millet is somewhat easier to establish 

than pearl millet, and although both are more 

drought tolerant than corn, pearl millet would be 

favored on sandy soils. 

Some vegetable growers in eastern states such 

as Maryland have planted foxtail millet after 

spring vegetable harvest as a cover crop. Control 

methods later in the summer have included spraying, 

mowing and rolling the crop flat (the rolling 

seems to provide a high percentage of control 

without need for further action). 

Disadvantages of foxtail millet are that it cannot 

be used after fall-harvested crops (too little vigor 

when planted in the cool fall months) and that it 

could be a host to some pests of other cereal grain 

crops—as is true of any grass cover crop. Foxtail 

millet is not likely to be a weed, since it does not 

have hard seed; any foxtail millet plants that volunteer 

the next season can be easily controlled 

similar to volunteer oats. 

Some seed dealers sell foxtail millet under a 

generic name, often as German millet (be sure 

you are getting foxtail millet, and not some other 

species such as proso millet or pearl millet). 

University cultivars include RED SIBERIAN, GOLDEN 

GERMAN,WHITE WONDER,SNO-FOX and MANTA. Seed 

dealers most likely to carry foxtail millet are those 

located in the Great Plains region, particularly in 

Nebraska. 

—Robert L. Myers, Jefferson Institute 

601 West Nifong Boulevard, Suite 1D, 

Columbia, MO 65203 

(573) 449-3518; rmyers@jeffersoninstitute.org 

Lupin 

White lupin (Lupinus albus) and blue or narrowleaf 

lupin (Lupinus angustifolius) are cool-season 

annual legumes that provide plenty of N and can 

be grown widely in the U.S.and southern Canada. 

As a fall and winter cover crop in the southeastern 

U.S., white lupin is the most cold-tolerant. 

Some cultivars overwinter as far north as the 

Tennessee Valley (287). Spring cultivars can be 

seeded in early April in the northern U.S. and 

southern Canada and plowed down around mid- 

June when they’re in the early-bloom to early-pod 

stage and at peak biomass. 

For use as a cover crop, drill lupins no deeper 

than 1 inch at rates varying from 70 lb./A (for 

small-seeded blue varieties) to 120 lb./A (for larger-seeded 

white varieties). At $30 to $40 per acre, 


the seed is relatively expensive. Be sure to inoculate 

lupin seed with compatible rhizobia. 

Lupins have aggressive taproots, especially the 

narrow-leaf cultivars, and they can fix up to 350 

lb. N/A. Under normal growth conditions and 

when killed in early spring, they typically contain 

100 to 150 lb. N/A in their biomass.You can kill 

lupins easily either mechanically or with herbicides.Their 

hollow stems crush or break readily, 

making it easy to plant cash crops using conservation 

tillage equipment. 

Lupin species were named after their original 

flower colors, but both species now have cultivars 

that may have white,blue or magenta/purple flowers.Blue 

lupin is adapted to the lower Coastal Plain 

and is more readily identified by its narrow leaflets 

(about 0.5-inch wide) rather than flower color. 

Only two lupin cultivars are readily available on 

a commercial scale:TIFWHITE-78,a white lupin,and 

TIFBLUE-78, a narrow-leaf lupin, both released by 

USDA’s Agricultural Research Service in the 

1980s. These two varieties, and other modern 

varieties, are “sweet” types as opposed to “bitter” 

types that were widely grown in the South prior 

to 1950. Sweet varieties have a low concentration 

of naturally occurring alkaloids.High alkaloid content 

in the plants makes lupin seed and forage 

unpalatable for livestock. 

Recent research suggests that alkaloids play a 

major role in resistance to disease and pests 

(including insects and nematodes). High-alkaloid 

lupins are therefore being selected and bred for 

use as cover crops rather than as animal feed. 

Anecdotal evidence suggests that sweet lupin 

cover crops can act as a trap crop for thrips 

(Frankliniella spp.) in cotton plantings. 

Lupins are susceptible to some fungal and viral 

diseases and should not be grown in the same 

field in successive years. It is best to rotate lupin 

cover crops with a small grain cover crop. 

For information about lupins and seed sources, 

contact: 

D.Wayne Reeves, Research Agronomist, 

USDA-ARS National Soil Dynamics Laboratory, 

411 S. Donahue St., P.O. Box 3439 

Auburn, AL 36832-5806 

(334) 844-4666; FAX: (334) 887-8597 

dreeves@ars.usda.gov 

Sunn hemp 

A tropical legume that grows rapidly, sunn hemp 

(Crotalaria juncea) can produce more than 

5,000 lb.dry matter/A and 120 lb.N/A in just nine 

to 12 weeks. It can fill a narrow niche between 

harvest of a summer crop and planting of a fall 

cash or cover crop. Sunn hemp sown by 

September 1 following a corn crop in Alabama,for 

example, can produce an average of 115 lb. N/A 

by December 1. 

Sunn hemp is not winter hardy and a hard 

freeze easily kills it. Sow sunn hemp a minimum 

of nine weeks before the average date of the first 

fall freeze. Seed at 40 to 50 lb./A, with a cowpeatype 

inoculant. 

Sunn hemp seed is expensive, about $2.25/lb., 

so the cost may be prohibitive for large-scale 

plantings. Seed can be produced only in tropical 

areas, such as Hawaii, and currently is imported 

only by specialty seed companies. 

A management caution: Many Crotalaria 

species contain alkaloids that are poisonous to 

livestock. However, the sunn hemp variety TROPIC 

SUN, developed jointly by the University of Hawaii 

and USDA-NRCS, has a very low level of alkaloid 

and is suitable for use as a forage. 

Research suggests that sunn hemp is resistant 

and/or suppressive to root-knot (Meloidogyne 

spp.) and reniform (Rotylenchulus reniformis) 

nematodes. 

—D.Wayne Reeves (see this page) 

Teff 

Teff (Eragrostis tef), or tef, is a grain grown primarily 

in Ethiopia, where it survives under harsh 

conditions in poor soils. Teff has been researched 

very little outside of east Africa, but has received 

occasional attention by U.S. researchers. Most 

small test plots have focused on teff as a cereal 

grain crop,but it also has potential as a forage,and 

is reportedly used some for grazing in South 

America and Australia. 

Limited studies point to teff’s ability to grow on 

poor soils. Although it is best to drill it, teff also 

can be established by broadcast seeding because 

the seed is less than 1 mm in size.This allows the 

seed to fall into cracks and crevices of a prepared 

soil and not lay exposed on the surface. However, 

UP-AND-COMING COVER CROPS 161

the fact that the seed is so tiny and light also could 

make it difficult to broadcast uniformly on a 

windy day, and makes the seed hard to handle in 

many conventional planters. If broadcast, the 

seedbed probably should be tilled first—no information 

is available about broadcasting it under 

no-till conditions. 

Teff grows relatively quickly, and, although 

short (18 to 24 in. tall), can establish a relatively 

good ground cover. The leaf blades are narrow, 

but the crop tends to establish a high number of 

plants per unit area.Teff is a warm season annual 

that is probably best planted in June in most 

states, which limits the conditions under which it 

would be cover cropped. It might possible to 

plant it later, but this has not been tested. 

The biggest limitation of teff as a cover crop is 

the lack of a seed source.The USDA-ARS National 

Plant Germplasm System maintains several genetic 

lines of teff available to researchers,but there is 

no commercial source of seed in the U.S. One 

farmer in the Pacific Northwest grows teff for 

Ethiopian restaurants and other buyers, but does 

not routinely distribute seed. This would be a 

good crop for a plant breeder to breed and release 

a variety for commercial distribution.Teff potentially 

could be used for temporary ground cover 

during construction, when soil is left bare for a 

period of months,but where a winter cover is not 

needed.Teff does not produce quite the biomass 

of some of the taller warm season grasses, but 

because it can be broadcast, it may confer some 

advantages. Teff has not become a volunteer or 

weed problem following several years of test 

plots in Missouri. Its potential for serving as an 

alternative pest host is unknown. 

—Robert L. Myers (see p. 160) 

APPENDIX C 

RECOMMENDED RESOURCES 

This list is for information purposes only. Inclusion does not 

imply endorsement, nor is criticism implied of similar 

resources not mentioned. 

Abdul-Baki,Aref and John R.Teasdale. 1997. 

Sustainable Production of Fresh-Market 

Tomatoes and Other Summer Vegetables with 

Organic Mulches. Farmers’ Bulletin No. 2279, 

USDA-ARS, Beltsville, Md. 23 pp. 

http://www.ars.usda.gov/is/np/tomatoes.html 

Appropriate Technology Transfer for Rural Areas 

(ATTRA). 1998. Cover Crops and Green 

Manures: Benefits, Uses and Literature 

Resources.ATTRA. Fayetteville,Ark. 

Bailey, R. G., P. E.Avers,T. King and W. H. McNab. 

1994. Ecoregions and subregions of the United 

States (map).Washington, DC: USDA Forest 

Service. 1:7,500,000.With supplementary table 

of map unit descriptions, compiled and edited 

by W. H. McNab and R. G. Bailey. 

http://www.fs.fed.us/land/ecosysmgmt/pages/ 

ecoreg1_home.html 

Barnes, Robert F., et al. 1995. Forages:The Science 

of Grassland Agriculture. 5th Edition. 2 vol. Iowa 

State Univ. Press,Ames, Iowa. 

Clark,Andrew J. et al. 1994. Seeding rate and kill 

date effects on hairy vetch-cereal rye cover crop 

mixtures for corn production.Agron. J. 86: 

1065-1070. 

Cramer, Craig, George DeVault, Mike Brusko, 

Fred Zahradnik and Lesa Ayers (eds.). 1985. The 

Farmer’s Fertilizer Handbook: How to make 

your own NPK recommendations…and make 

them pay. Regenerative Agriculture Association, 

Emmaus, Pa. 176 pp. 

Dabney, S. M. 1995. Cover crops in reduced 

tillage systems. pp. 126-127. Proc. Beltwide 

Cotton Conferences. 5 Jan 1995. National Cotton 

Council, Memphis,Tenn. 


Dyer, David A. 1998. Conservation Legume 

Varieties in the United States. USDA Handbook. 

Plant Materials Center, P.O. Box 68, Lockeford, 

Calif. 95237, (209) 727-5319. 

Duke, James A. 1981. Handbook of Legumes of 

World Economic Importance. Plenum Press, N.Y. 

343 pp. Compendium of botanical, cultural and 

management information. Excellent line 

drawings. 

Duval, Jean. 1997. Cover Cropping in Potato 

Production. Ecological Agriculture Projects. 

Publication No. 72.An eight-page bulletin with 

concise descriptions of how to use legume, 

cereal and brassica cover crops; excellent chart 

for planning rotations with benefit analysis of 

various covers. 

Hanson, James C. et al. 1993. Profitability of 

no-tillage corn following a hairy vetch cover 

crop. J. Prod.Ag. 6:432-437. 

Hanson, James C. et al. 1997. Organic versus 

conventional grain production in the mid- 

Atlantic: an economic and farming system 

overview. Amer. J.Alt. Ag. 12:2-9. 

Hargrove,W.L. (ed.). 1991. Cover Crops for Clean 

Water. Proc. Int’l Conf.April 9-11, 1991.West 

Tennessee Experiment Station, Jackson,Tenn. Soil 

and Water Conservation Society.Ankeny, Iowa. 

Hofstetter, Bob. 1988. The New Farm’s cover 

crop guide: 53 legumes, grasses and legume-grass 

mixes you can use to save soil and money. The 

New Farm 10:17-22, 27-31. 

Ingels,Chuck A.et al.1994.Selecting the right cover 

crop gives multiple benefits.Calif.Ag. 48:43-48. 

Ingels, C.A., R.L. Bugg, G.T. McGourty, and L.P. 

Christensen. 1998. Cover Cropping in Vineyards: 

A Grower’s Handbook. University of California, 

Div. of Agriculture and Natural Resources. In 

Press. Chapters on cover crop species, soil/water 

management, pest management, 12 growers. 

Charts of seeding rates, seed costs. 

Macey,Anne. 1992. Organic Field Crop 

Handbook. Canadian Organic Growers Inc., 

Ottawa, Ont. 192 pp. Practical handbook covering 

principles of organic farming, how to design 

crop rotations and species-specific chapters on 

11 cash and cover crops. 

Matheson, Nancy, Barbara Rushmore, James R. 

Sims, Michael Spengler and E.L. Michalson. 1991. 

Cereal-Legume Cropping Systems: Nine farm 

case studies in the dryland northern plains, 

Canadian prairies and intermountain 

Northwest.Alternative Energy Resources 

Organization (AERO), Helena, Mont. 75 pp.An 

excellent description of these innovative systems 

with clear diagrams and great management detail 

of how crops are selected. 

MacRae, R.J. and G.R. Mehuys. 1985.The effect of 

green manuring on the physical properties of 

temperate-area soils. Adv. Soil Sci. 3:71-94. 

McVay, K.A. et al. 1989.Winter legume effects on 

soil properties and nitrogen fertilizer requirements. 

Soil Sci. Soc. of Amer. J. 53:1856-1862. 

Michigan State University. 1996. Cover Crops 

Symposium Proceedings. Michigan State 

University,W.K. Kellogg Biological Station, Battle 

Creek, Mich. 20 pp. 

Miller, P.R. et al. 1989. Cover Crops for California 

Agriculture. University of California, Div. Of Ag. 

and Natural Resources Publication 21471, 24 pp. 

Oakland, Calif. 

National Assn. of Wheat Growers Foundation. 

1995. Best Management Practices for Wheat: 

A Guide to Profitable and Environmentally 

Sound Production. National Assn. of Wheat 

Growers Foundation.Washington, DC. 

Oregon State University. 1998. Using Cover 

Crops in Oregon. Publication #EM-8704. 

Available for $5.50 from Publication Orders, 

Extension and Station Communications, 

Oregon State University, 422 Kerr Administration, 

Corvallis, OR 97331. 

RECOMMENDED RESOURCES 163

Reeves, D.W. 1994. Cover crops and rotations. pp. 

125-172. In J.L. Hatfield and B.A. Stewart (eds.). 

Crops Residue Management. 1994. Lewis 

Publishers,Ann Arbor, Mich. 

Sainju, Upendra M. and Bharat P. Singh. 1997. 

Winter cover crops for sustainable agricultural 

systems: Influence on soil properties, water 

quality and crop yields. Hort Sci. 32:21-28. 

Comprehensive overview of cover crop effects 

on N, soil organic C and N properties; chart on 

N contributions, water nitrate movement, 

research needs. 

Sarrantonio, Marianne. 1994. Northeast Cover 

Crop Handbook. Soil Health Series. Rodale 

Institute, Kutztown, Pa. 118 pp. 

Sarrantonio, M. 1991. Methodologies for 

screening soil-improving legumes. Rodale 

Institute. Kutztown, Pa. 

Shirley, Christopher and The New Farm staff. 

1993. What Really Happens When You Cut 

Chemicals Rodale Institute, Kutztown, Pa. Lots 

of farmer profiles and details on usage of covers. 

Smith, Miranda et al. 1994. The Real Dirt: 

Farmers Tell About Organic and Low-Input 

Practices in the Northeast. Northeast Organic 

Farming Association and Northeast Region SARE, 

Burlington,Vt. 264 pp. 

Stute, Jim. 1996. Legume Cover Crops in 

Wisconsin. Wisconsin Department of Agriculture, 

Sustainable Agriculture Program. Madison,Wis. 

27pp. 

Stute, J.K. and J.L. Posner. 1995. Legume cover 

crops as a nitrogen source for corn in an 

oat-corn rotation. J. Prod.Ag. 8:385-390. 

Sustainable Agriculture Network. 1997. 

Steel in the Field:A Farmer’s Guide to Weed 

Management Tools. Greg Bowman, ed. 

Sustainable Agriculture Network. Beltsville, Md. 

Shows how today’s implements and techniques 

can control weeds while reducing—or eliminating—herbicides. 

Farmer accounts include how 

cover crops and tillage tools are used in tandem 

to control weeds. 

Teasdale, John R. 1996. Contribution of cover 

crops to weed management in sustainable 

agriculture systems. J. Prod.Ag. 9:475-479. 

University of California Sustainable Agriculture 

Research and Education Program. 1997. Cover 

Crops: Resources for Education and Extension. 

David Chaney and Ann D. Mayse, compilers. 

.Three-ring binder of 

educational resources including Internet, print 

materials, cover crop profiles, videos and slide 

sets, and a list of experts. 

University of Wisconsin et al. 1990. Alternative 

Field Crops Manual. Univ. of Wisconsin- 

Extension and Univ. of Minnesota, Madison,Wis. 

and St. Paul, Minn.Three-ring binder with 

detailed descriptions of agronomic use for 35 

crops and short narratives on 13 more crops. 

Tabbed, referenced. 

Wagger, Michael G. 1989.Winter annual cover 

crops. pp. 59-61. In M.C. Cook and W.M. Lewis 

(Eds.). Conservation Tillage for Crop Production. 

Publication No.AG-407.Agricultural Extension 

Service, North Carolina State University. Crimson, 

hairy vetch, cahaba vetch, field peas mentioned 

in this brief overview of planting and managing 

cover crops. 

Zalom, Frank G. 1995.A cover crop system for 

vineyard pest, weed and nutrition management. 

#LW91-26.Western Regions SARE. Utah State 

Univ. Logan, Utah. Describes management of winter 

annuallegume/grass cover crops to control 

leafhoppers, spider mites and weeds. 


OTHER RESOURCES 

Cover Crops On The Web 

To keep up with the growing cover crop resources on the Internet’s World Wide Web, point your 

browser to these sites: 

USDA Sustainable Agriculture Network 

http://www.sare.org 

Browse or search for cover crop information: 

The first edition of Managing Cover Crops 

Profitably, the database of SARE projects, and 

the archives of the sustainable agriculture listserv, 

sanet-mg. 

Managing Cover Crops Profitably 

USDA Sustainable Agriculture Network 

http://www.sare.org/publications/covercrops.html/ 

See the on-line version of this book in pdf format. 

Cover Crop Resource Page 

Sustainable Agriculture Research and Education 

Program (SAREP) 

University of California 

http://www.sarep.ucdavis.edu/ccrop 

An extensive site (not just for California farmers) 

that includes a searchable database of more than 

5,000 items, 400 online images and detailed 

information on 32 cover crop species. Many 

valuable gleanings from the scientific literature 

compiled in useful, readable form. 

ATTRA 

http://attra.ncat.org 


(ATTRA), a nation-wide sustainable farming information 

center located at the University of 

Arkansas, has a website that features many of 

the publications and resource lists developed by 

program specialists in response to inquiries from 

farmers since 1987. Call 1-800-346-9140 

HELPFUL VIDEOS 

No-Till Vegetables—A Sustainable Way to 

Increase Profits, Save Soil and Reduce 

Pesticides 

This 38-minute video covers the basics of sustainable 

no-till vegetable production including 

no-till transplanting into cover crops, pioneered 

by Pennsylvania grower Steve Groff. Send $24.95 

($26.95 for overseas orders) check or money 

order to: Cedar Meadow Farm, 679 Hilldale Road, 

Holtwood Pa. 17532. For more info, email: 

sgroff@epix.net or phone (717) 284-5152. 

Using Cover Crops in Conservation 

Production Systems 

An 11-minute video from the USDA-ARS National 

Sedimentation Lab in Oxford, MS, this program 

can be obtained for $10 (postpaid) from: 

Shepherd Productions, 5004 Sequoia Rd, 

Memphis,TN 38117-2016, (901) 272-0350. 

Controlled Rotational Cover Cropping in 

the Bio-Extensive Market Garden 

This 52-minute video ($10) explains how 

intensive cover cropping serves as the base for 

carefully planned rotations of many crops in the 

Nordell’s whole-farm vegetable system. Booklet 

($10) also available (postpaid) from: Eric and 

Anne Nordell, Beech Grove Farm, 3410 Route 

184,Trout Run, Pa. 17771. 

Farmers and their Innovative Cover 

Cropping Techniques 

A 70-minute educational video featuring 10 

farms from five northeastern states. $15. See 

www.uvm.edu/vtvegandberry/videos/ 

covercropsvideo.html. 

RECOMMENDED RESOURCES 165

APPENDIX D 

SEED SUPPLIERS 


imply endorsement, nor is criticism implied of firms not 

mentioned. 

Adams-Briscoe Seed Co. Inc. 

P.O. Box 19 

325 E. Second St. 

Jackson, GA 30233-0019 

770-775-7826 

fax 770-775-7122 

abseed@juno.com 

http://www.abseed.com 

forage/grain legumes, grains, summer annuals, 

wildlife 

Alabama Farmers Co-op 

P.O. Box 2227 

Decatur,AL 35609 

256-353-6843 

fax 256-350-1770 

small grains, forage/grain legumes, summer 

annuals (120 retail outlets) 

Albert Lea Seedhouse Inc. 

P.O. Box 127 

Albert Lea, MN 56007 

800-352-5247 

tom@alseed.com 

http://www.alseed.com 

grains, forage/grain legumes, grasses 

Albright Seed Company 

487 Dawson Drive, Bay 5S 

Camarillo, CA 93012 

805-484-0551 

800-423-8112 

fax 805-987-9021 

paul@albrightseed.com 

http://www.albrightseed.com 

legumes, grasses and grains adapted to 

California bioregions 

Ampac Seed Co. 

P.O. Box 318 

Tangent, OR 97389 

800-547-3230 

fax 541-928-2430 

info@ampacseed.com 

http://ampacseed.com 

forage grasses, legumes 

Barenbrug 

33477 Highway 99 East 

Tangent, OR 97389 

541-926-5801 

800-547-4101 

fax 541-926-9435 

forage legumes, grasses 

Birkett Mills 

P.O. Box 440 

Penn Yan, NY 14527 

315-536-3311 

fax 315-536-6740 

buckwheat 

Brett-Young Seeds Ltd. 

Box 99, St. Norbert Postal Station 

Winnipeg, MB, Canada R3V 1L5 

204-261-7932 

800-665-5015 (Canada) 

fax 204-275-7333 

byseeds@cyberspc.mb.ca 

forage legumes 

Budd Seed 

191 Budd Blvd. 

Winston-Salem, NC 27114-5087 

800-543-7333 

336-760-9060 

fax 336-765-3168 

grasses, red clover, subclover 


Cal/West Seeds 

Box 1428 

Woodland, CA 95776-1428 

800-327-3337 

800-824-8585 

fax 530-666-5317 

whl: legumes, forages, clovers, 

Sudangrasses, vetches 

Corland Seeds 

P.O. Box 336 

Guelph, ON N1H 6K5 

519-763-2059 

800-265-4321 

fax 519-763-5192 

legumes, forages 

DEKALB Genetics Corporation 

3100 Sycamore Road 

DeKalb, IL 60115-9600 

800-833-5252 

dekalb@dekalb.com 

http://www.dekalb.com 

whl: sorghum-Sudangrass hybrids, forages 

Discount Seed Inc. 

P.O. Box 84 

2411 9th Ave SW 

Watertown, SD 57201 

605-886-5888 

fax 605-886-3623 

grains, forage/grain legumes, forage grasses 

Ernst Conservation Seeds 

9006 Mercer Pike 

RD 5 Box 806 

Meadville, PA 16335 

814-336-2404 

fax 814-336-5191 

ernst@gremlan.org 

http://www.ernstseed.com 

forage legumes, native species, wildlife 

Fedco Seeds 

P.O. Box 520 

Waterville, ME 04903 

207-873-7333 

fax (same) 

grains, forage/grain legumes, brassicas 

Fizzle Flat Farms—Marvin Manges 

18773 E. 1600 Ave. 

Yale, IL 62481 

618-793-2060 

fax (same) 

buckwheat, hairy vetch, rye (some certified 

organic) 

Frazier Seed Co. 

309 W. Main St. 

Anthony, KS 67003 

316-842-5106 

grains, cowpeas, winter peas 

Harmony Farm Supply & Nursery 

P.O. Box 460 

Graton, CA 95444 

707-823-9125 

fax 707-823-1734 

forage/grain legumes 

Hobbs and Hopkins Ltd. 

1712 SE Ankeny Street 

Portland, OR 97214 

503-239-7518 

fax 503-230-0391 

lawn@teleport.com 

grasses 

Hytest Seeds 

454 Railroad Ave. 

P.O. Box 3147 

Shiremanstown, PA 17011 

717-737-4529 

800-442-7391 

fax 717-737-7168 

grains, forage legumes, summer annuals 

SEED SUPPLIERS 167

Johnny’s Selected Seeds 

Foss Hill Road 

Albion, ME 04910 

207-437-9294 

fax 207-437-2165 

customerservice@johnnyseeds.com 

http://www.johnnyseeds.com 

grains, forage/grain legumes, rapeseed 

(some untreated) 

Kamprath Seed Co. 

205 Stockton St. 

Mateca, CA 95337 

209-823-6242 

800-325-4621 

fax 209-823-2582 

many medics, subclovers, clovers, grasses, 

other legumes 

Kaufman Seeds 

P.O. Box 398 

Ashdown,AR 71822 

870-898-3328 

800-892-1082 

wholesale (50-lb. min.): grains, forage/grain 

legumes, grasses, summer annuals 

Lohse Mill 

7752 County Road 29 

Glenn, CA 95943 

530-934-2157 

fax 530-934-9106 

grains, forage/dryland legumes 

McDonald Ag Corp. 

P.O. Box 828 

McMinville, OR 97128 

503-472-5158 

kmac@mcag.com 

crimson and red clover by cultivar 

Minnesota Seed Solutions 

7800 State Highway 101 

Shakopee, MN 55379 

612-445-2606 

wholesale (50-lb. min.): forgage/grain legumes, 

grains, grasses 

Missouri Southern Seeds 

P.O. Box 699 

Rolla, MO 65402 

573-364-1336 

800-844-1336 

fax 573-364-5963 

wholesale (w/retail outlets): grains, forage 

legumes, grasses, summer annuals 

North Country Organics 

P.O. Box 372 

203 Depot St. 

Bradford,VT 05033 

802-222-4277 

fax 802-222-9661 

forage legumes, summer annuals 

Olds Seed Solutions 

2901 Packers Avenue 

Madison,WI 53704 

608-249-9291 

800-356-7333 

fax 608-249-0695 

forage legumes, brassicas, summer annuals, 

grasses 

Peaceful Valley Farm Supply 

P.O. Box 2209 

Grass Valley, CA 95945 

916-272-4769 

fax 530-272-4794 

http://www.groworganic.com 

grains, grasses, forage/grain legumes, brassicas, 

sunn hemp 

Pennington Seeds 

P.O. Box 290 

Madison, GA 30650 

800-285-7333 

seeds@penningtonseed.com 

http://www.penningtonseed.com 

grains, grasses, forage legumes 


Pick Seed Canada 

P.O. Box 304 

1 Greenfield Rd 

Lindsey, ON K9V 4S3 

905-623-2660 

fax 705-878-9249 

clovers, grasses 

P.L. Rohrer & Bro. Co. 

P.O. Box 250 

Smoketown, PA 17576 

717-299-2571 

fax 717-299-5347 

grains, grasses, forage legumes, brassicas 

Rupp Seeds, Inc. 

17919 Co. Rd. B 

Wauseon, OH 43567 

419-337-1841 

fax 419-337-5491 

grains, grasses, forage legumes 

Seedway Inc. 

P.O. Box 250 

Hall, NY 14463 

800-836-3710 

fax 716-526-6832 

Grains, forage/grain legumes, grasses, brassicas, 

summer annuals 

Seimer/Mangelsdorf Seed Co. 

96300 Collinsville Rd. 

East St. Louis, IL 62201 

800-467-7333 

fax 618-271-4199 

grains, cowpeas, summer annuals, wildlife 

Southern States Cooperative 

2600 Durham St. 

Richmond,VA 23220 

800-868-6273 

wholesale (retail outlets in 6 states): grains, 

forage legumes, cowpeas, summer annuals 

Sweeney Seed Company 

110 South Washington St. 

Mount Pleasant, MI 48858 

517-773-5391 

800-344-2482 

fax 517-773-1216 

forage legumes, peas, summer annuals, rape 

Tennessee Farmers Co-op 

200 Waldron Road 

P.O. Box 3003 

LaVergne,TN 37086 

615-793-8506 

grains, forage legumes, peas 

Timeless Seeds 

P.O. Box 881 

Conrad, MT 59425 

406-278-5770 

fax 406-278-5720 

timeless@timeless-seed.com 

dryland forage/grain legumes 

The Wax Co., Inc. 

204 Front St. N 

Amory, MS 38821 

662-256-3511 

annual ryegrass 

Welter Seed and Honey Co. 

17724 Hwy. 136 

Onslow, IA 52321-7549 

319-485-2762 

800-728-8450 

800-470-3325 

grains, grasses, forage/grain legumes, 

summer annuals 

Wolf River Valley Seeds 

N2976 County M 

White Lake,WI 54491 

715-882-3100 

800-359-2480 

wrvs@newnorth.net 

grains, forage/grain legumes 

SEED SUPPLIERS 169

INOCULANT SUPPLIERS 

LiphaTech Inc. (Nitragin inoculants) 

3101 W. Custer Ave. 

Milwaukee,WI 53209 

414-462-7600 

800-558-1003 

fax 414-462-7186 

cs1@execpc.com 

http://www.liphatech.com 

inoculants for major/minor temperate, 

tropical climate legumes 

Urbana Laboratories 

P.O. Box 1393 

310 S.Third St. 

St. Joseph, MO 64502 

816-233-3446 

800-892-2013 

fax 816-233-8295 

urbana@ponyexpress.net 

inoculants for major/minor 

temperate climate legumes 

APPENDIX E 

FARMING ORGANIZATIONS WITH 

COVER CROP EXPERTISE 


imply endorsement, nor is criticism implied of organizations 

not mentioned. 

Note: CC denotes cover crop(s) or cover cropping. 

ORGANIZATIONS—NORTHEAST 

The Accokeek Foundation 

3400 Bryan Point Road 

Accokeek, MD 20607 

301-283-2113 

fax 301-283-2049 

Accofound@accokeek.org 

http://www.accokeek.org 

land stewardship and ecological agriculture 

using CC 

Center for Sustainable Agriculture 

590 Main St. 

Burlington,VT 05405 

802-656-5459 

fax 802-656-8874 

susagctr@zoo.uvm.edu 

http://www.uvm.edu/~susagctr 

Chesapeake Wildlife Heritage 

P.O. Box 1745 

Easton, MD 21601 

410-822-5100 

fax 410-822-4016 

info@cheswildlife.org 

http://www.cheswildlife.org 

CC in organic & sustainable farming systems; 

consulting & implementation in Mid-shore Md 

area as they relate to farming & wildlife 

Pennsylvania Association for Sustainable 

Agriculture (PASA) 

P.O. Box 419 

114 W. Main St 

Millheim, PA 16854 

814-349-9856 

fax 814-349-9840 

info@pasafarming.org 

http://www.pasafarming.org 

on farm CC demonstrations 


SARE Northeast Region Office 


10 Hills Building 


802-656-0471 

fax 802-656-4656 

nesare@zoo.uvm.edu 

http://www.uvm.edu/~nesare/index.html 

ORGANIZATIONS—NORTH CENTRAL 

Center for Integrated Agricultural Systems 

(CIAS) 

University of Wisconsin-Madison 

1450 Linden Drive 

Madison,WI 53706-1562 

608-262-5200 

fax 608-265-3020 

kmartint@facstaff.wisc.edu 

http://www.wisc.edu/cias/ 

CC resource locator in Wisconsin/ 

Upper Midwest 

Conservation Technology Information 

Center (CTIC) 

1220 Potter Drive, Rm 170 

West Lafayette, IN 47906 

765-494-9555 

fax 765-494-5969 

ctic@ctic.purdue.edu 

http://www.ctic.purdue.edu 

conservation tillage series fact sheets provider 

Land Stewardship Project 

2200 4th Street 

White Bear Lake, MN 55110 

612-653-0618 

fax 612-653-0589 

lspwbl@landstewardshipproject.org 

http://www.misa.umn.edu/~lsp/ 

Leopold Center for Sustainable Agriculture 

Iowa State University 

209 Curtiss Hall 

Ames, IA 50011-1050 

515-294-3711 

fax 515-294-9696 

leocenter@iastate.edu 

http://www.ag.iastate.edu/centers/leopold 

support research, demos, education projects in 

Iowa on CC systems 

SARE North Central Region Office 

University of Nebraska-Lincoln 

13-A Activities Bldg. 

P.O. Box 830840 

Lincoln, NE 68583 

402-472-7081 

fax 402-0280 

ncsare@unl.edu 

http://www.sare.org/ncrsare/ 

ORGANIZATIONS—SOUTH 

Appropriate Technology Transfer for Rural 

Areas (ATTRA) 

P.O. Box 3657 

Fayetteville,AR 72702 

1-800-346-9140 

http://attra.ncat.org/ 

ATTRA is a leading information source for 

farmers and extension agents thinking about 

sustainable farming practices 

Educational Concerns for Hunger 

Organization 

ECHO 

17430 Durrance Rd. 

North Ft. Myers, FL 33917 

941-543-3246 

fax 941-543-5317 

echo@echonet.org 

http://www.echonet.org/ 

provides technical information and seeds of 

tropical cover crops 

ORGANIZATIONS 171

The Kerr Center for Sustainable 

Agriculture Inc. 

PO Box 588 

Highway 271 South 

Poteau, OK 74953 

918-647-9123 

fax 918-647-8712 

http://www.kerrcenter.com/ 

CC systems demonstrations & research 

SARE Southern Region Office 

University of Georgia 

1109 Experiment Street 

Georgia Station 

Griffin, GA 30223-1797 

770-412-4787 

fax 770-412-4789 

groland@gaes.griffin.peachnet.edu 

http://www.griffin.peachnet.edu/sare/ 

Texas Organic Growers Association 

P.O. Box 15211 

Austin,TX 78761 

1-877-326-5175 

fax 512-842-1293 

townsend@hillsboro.net 

http://www.texasorganicgrowers.com/ 

TOGA is helping to make organic agriculture 

viable in Texas and offers a quarterly periodical. 

ORGANIZATIONS—WEST 

Center for Agroecology & Sustainable Food 

Systems 

1156 High Street 

Santa Cruz, CA 95064 

831-459-4367 

fax 831-459-2799 

http://zzyx.ucsc.edu/casfs/ 

facilitates the transfer of successful organic 

farming and technical advice 

Northern Plains Sustainable 

Agriculture Society 

9824 79th St S.E. 

Fullerton, ND 58441-9725 

701-883-4304 

fax 701-883-4304 

tpnpsas@drtel.net 

http://www.npsas.org 

CC systems for small grains 

SARE Western Region Office 

Utah State University 

4865 Old Main Hill 

Room 322 

Logan, UT 84322 

435-797-2257 

wsare@mendel.usu.edu 

http://wsare.usu.edu/ 

Small Farm Center 


One Shields Avenue 

Davis, CA 95616 

530-752-8136 

fax 530-752-7716 

sfcenter@ucdavis.edu 

http://www.sfc.ucdavis.edu/ 

serves as a clearinghouse for questions from 

farmers, marketers, farm advisors, trade associations, 

government officials and agencies, and the 

academic community 

University of California SAREP 


Davis, CA 95616-8716 

530-752-7556 

fax 530-754-8550 

sarep@ucdavis.edu 

http://www.sarep.ucdavis.edu/ 


APPENDIX F 

REGIONAL EXPERTS 

These individuals are willing to briefly respond to specific 

questions in their area of expertise, or to provide referral to 

others in the sustainable agriculture field. Please respect 

their schedules and limited ability to respond. 

Note: CC denotes cover crop(s) or cover cropping. 

NORTHEAST 

Aref A.Abdul-Baki 

USDA/ARS Vegetable Lab 

BARC-West 

Bldg. 010A Rm 213 

10300 Baltimore Ave 

Beltsville, MD 20705 

301-504-5057 

fax 301-504-5555 

Aref.Abdul-Baki@usda.gov 

CC systems for vegetables, soil permeation & fertility 

C.E. Beste 

27664 Nanticoke Rd. 

Salisbury, MD 21801 

410-742-8780 

fax 410-742-1922 

cb20@umail.umd.edu 

CC systems & no-till equipment for vegetables 

Andy Clark-SAN Coordinator 


10300 Baltimore Ave, Bldg. 046 


301-504-6425 

fax 301-504-5207 

san@sare.org 

http://www.sare.org 

technical information specialist for sustainable 

agriculture; legume/grass CC mixtures 

Jim Crawford 

New Morning Farm 

HCR 71, Box 168B 

Hustontown, PA 17229 

814-448-3904 

fax 814-448-2333 

25 years of CC in vegetable production systems 

Mark Davis 

USDA/ARS Soil Microbial Systems 

BARC-West 

Bldg. 001, Rm 137 

Beltsville, MD 20705-2350 

301-504-9068 x342 

fax 301-504-8370 

mdavis@asrr.arsusda.gov 

CC for organic cropping systems 

A. Morris Decker 

5102 Paducah Rd. 

College Park, MD 20740 

301-441-2367 

Prof. Emeritus, University of Maryland. 40 years 

forage mgt., CC & agronomic cropping systems 

research 

Steve Groff 

Cedar Meadow Farm 

679 Hilldale Rd. 

Holtwood, PA 17532 

717-284-5152 

fax 717-284-5967 

sgroff@epix.net 

http://www.cedarmeadowfarm.com 

CC/no-till strategies for vegetable & 

agronomic crops 

REGIONAL EXPERTS 173

H.G. Haskell 

4317 S. Creek Rd. 

Chadds Ford, PA 19317 

tel/fax 610-388-0656 

rye/vetch mix for green manure and erosion 

control 

Zane R. Helsel, Director of Extension 

Rutgers Cooperative Extension 

Rutgers,The State University of NJ 

88 Lipman Dr. 

New Brunswick, NJ 08901-8525 

732-932-5000 x581 

fax 732-932-6633 

helsel@aesop.rutgers.edu 

http://www.rce.rutgers.edu 

CC for field crop systems 

Stephen Herbert 

University of Massachusetts 

Dept. of Plant & Soil Sciences 

Bowditch Hall, Box 30910 

Amherst, MA 01003 

413-545-2250 

fax 413-545-0260 

sherbert@pssci.umass.edu 

CC culture, soil fertility, crop nutrition & nitrate 

leaching 

Bob Hofstetter 

Indian Rock Produce 

530 California Road 

Quakertown, PA 18951 

215-538-1328 

CC for inter-seeding and over-seeding in field & 

vegetable crops 

Dr. Amadou Makhtar Diop 

Information Coordinator 

The Rodale Institute 

611 Siegfriedale Rd. 

Kutztown, PA 19530 

610-683-1400 

fax 610-683-8548 

info@rodaleinst.org 

http://www. rodaleinstitute.org 

333 acre farm & demonstration garden w/ CC; 

contact info and publications provider 

Jack Meisinger 

USDA/ARS 

BARC-West 

Bldg. 007 Rm 205 



301-504-5276 x431 

jmeising@asrr.arsusda.gov 

nitrogen management in CC systems 

Anne and Eric Nordell 

3410 Route 184 

Trout Run, PA 17771 

570-634-3197 

rotational CC for weed control 


University of Maine 

102 Deering Hall 

Orono, ME 04469 

207-581-2913 

fax 207-581-2999 

mariann2@maine.edu 

legumes, soil health & nitrogen cycling 

Eric Sideman 

Maine Organic Farmers & Gardeners Assoc. 

P.O. Box 170 

Common Ground County Fair 

Unity, ME 04988 

207-568-4142 

fax 207-568-4141 

esideman@mofgo.org 

http://www.mofga.org/ 

MOFGA offers information & technical bulletins 

on CC selection & growth 

John Teasdale 

USDA/ARS 

BARC-West 

Bldg. 001 Rm 323 



301-504-5504 

fax 301-504-6491 

teasdale@ba.ars.usda.gov 

CC mgt./mixtures & weed suppression 


David W. Wolfe 

Cornell University 

168 Plant Science Bldg. 

Ithaca, NY 14853 

607-255-7888 

fax 607-255-9998 

dww5@cornell.edu 

CC for improved soil quality in vegetable 

cropping systems 

NORTH-CENTRAL 

Dan Anderson 

University of Illinois Agroecology/Sustainable 

Agriculture Program 

W-503 Turner Hall 

1102 S. Goodwin 

Urbana, IL 61801 

217-333-1588 

fax 217-333-7370 

aslan@uiuc.edu 

on-farm CC trials throughout Illinois 

Rich Bennett 

RR 5 

7 740 P3 

Napoleon, OH 43545 

419-748-8187 

CC for soil quality & herbicide/pesticide reduction 

John Cardina 

Ohio State University-OARDC 

215 Williams Hall 

Wooster, OH 44691 

330-263-3644 

cardina.2@osu.edu 

CC for sustainable weed control 

Stephan A. Ebelhar 

Dixon Springs Agricultural Center 

Route 1, Box 256 

Simpson, IL 62985 

618-695-2790 

fax 618-695-2492 

sebelhar@uiuc.edu 

CC systems for no-till corn & soybeans 

Greg Endres 

Carrington Research Extension Center 

NDSU-CREC 

Box 219 

Carrington, ND 58421 

701-652-2951 x108 

fax 701-652-2055 

gendres@ndsuext.nodak.edu 

cropping systems & weed mgt. in the Dakotas 

Rick Exner 

Practical Farmers of Iowa 

ISU Extension Service 

2104 Agronomy Hall 

Ames, IA 50011 

515-294-5486 

fax 515-294-9985 

dnexner@iastate.edu 

http://www.pfi.iastate.edu 

on farm CC research for the upper Midwest 

Carmen M. Fernholz 

State Chair of the SFA of MN 

Rt. 2 Box 9A 

Madison, MN 56256 

320-598-3010 

fax 320-598-7347 

fernh001@umn.edu 

Robert N. Fogg 

Fogg Organic Farms 

2665 Bellevue Rd. 

Leslie, MI 49251 

517-589-5590 

fax 517-589-5596 

CC for soil improvement in a closed organic 

system 

Dr. Mohammadreza Ghaffarzadeh 

Research Manager 

Agronomy Services 

Pioneer Hi-Bred International 

6900 NW 62nd Ave. 

Johnston, Iowa 50131-0256 

ghaffarzm@phibred.com 

sustainable cropping systems using berseem 

clover 


Walter Goldstein or Jim Stute 

Michael Fields Agricultural Institute 

W2493 County ES 

East Troy,WI 53120 

262-642-3303 

fax 262-642-4028 

mfai@mfai.org 

CC for nutrient cycling & soil health in biodynamic 

& conventional systems 

Richard R. Harwood 

Michigan State University 

Crop & Soil Sciences Dept. 

260 Plant & Soil Sciences Bldg. 

East Lansing, MI 48824 

517-432-1611 

fax 517-353-3834 

rharwood@msu.edu 

CC systems & field crop agroecology 

Frederick Kirschenman 

Rt 1 Box 73 

Winsor, ND 58424 

701-763-6287 

fax 701-486-3580 

CC systems for cereal grains, soil quality 

& pest mgt. 

Matt Liebman 

Iowa State University 

Department of Agronomy 

3218 Agronomy Hall 

Ames, IA 50011 

mliebman@iastate.edu 

green manures & CC for field and vegetable 

systems 

Dale Mutch 

W.K. Kellogg Biological Station 

District IPM Agent 

3700 E. Gull Lake Dr. 

Hickory Corners, MI 49060-9505 

616-671-2412 

fax 616-671-4485 

mutchd@msue.msu.edu 

http://www.msue.msu.edu/sycamore/cover.htm 

general CC information provider 

Rob Myers 

Jefferson Institute 

601 West Nifong Blvd, Suite 1D 

Columbia, MO 65203 

573-449-3518 

fax 573-449-2398 

rmyers@jeffersoninstitute.org 

CC systems and crop diversification 

Michael Rahe 

Bureau of Land and Water Resources 

Illinois Dept. of Agriculture 

P.O. Box 19281 

Springfield, IL 62794-9281 

217-782-6297 

fax 217-524-4882 

Mrahe@agr084rl.state.IL.us 

CC information for referrals, research & projects 

David R. Swaim 

Swaim & Associates 

Agronomic Consulting 

1730 Camp Rotary Road 

Crawfordsville, IN 47933 

765-362-4946 

fax 765-361-9096 

dswaim@tctc.com 

CC with conservation tillage, soil fertility & crop 

nutrition 

Richard Thompson 

Thompson On-Farm Research 

2035 190th St. 

Boone, IA 50036-7423 

515-432-1560 

CC system in corn-soybean-corn-oats-hay rotation 

SOUTH 

Philip J. Bauer 

USDA/ARS 

Cotton Production Research Center 

2611 Lucas St. 

Florence, SC 29501-1241 

843-669-5203 x7250 

fax 843-662-3110 

bauer@florence.ars.usda.gov 

CC systems for cotton production 


Bob Burdette 

Southern Seed Certification Assoc. 

P.O. Box 2619 

Auburn,AL 36831 

334-821-7400 or 334-844-4995 

specialty CC & seed development 

Nancy Creamer 

North Carolina State University 

Horticultural Science Dept. 

Box 7609 

Raleigh, NC 27695 

919-515-9447 

fax 919-515-2505 

nancy_creamer@ncsu.edu 

CC systems for no-till vegetables & weed control 

Seth Dabney 

USDA/ARS 

National Sedimentation Lab 

P.O. Box 1157 

Oxford, MS 38655 

662-232-2975 

fax 662-232-2915 

dabney@sedlab.olemiss.edu 

legume reseeding & mechanical control of CC in 

the mid-South 

Phillip Davis 

Route 1 Box 208 

Old Fort, NC 28762 

tel/fax 828-668-9800 

CC for corn, soybeans & tobacco 

Mario DeLuca 

McDowell County Extension Service 

County Administration Bldg., Rm 226 

Marion, NC 28752 

828-652-7121 ext. 249 

fax 828-659-3484 

mdeluca@mcdowell.ces.ncsu.edu 

http://mcdowell.ces.state.nc.us/staff/mdeluca/pe 

rsonalold.html 

CC information for corn and soybean 

production mgt. 

Greg D. Hoyt 

MHCREC 

2016 Fanning Bridge Rd. 

Fletcher, NC 28732 

828-684-3562 

greg_hoyt@ncsu.edu 

CC for vegetables, tobacco & corn 

Noah N. Ranells 


1114A Williams Hall 

Box 7620 

Raleigh, NC 27695-7620 

919-515-7597 

fax 919-515-5885 

noah_ranells@ncsu.edu 

grass/legume CC for improved water quality 

D. Wayne Reeves 

USDA/ARS 

National Soil Dynamics Laboratory 

411 S. Donahue St. 

Auburn,AL 36832-5806 

wreeves@acesag.auburn.edu 

334-844-4666 

fax 334-887-8597 

K.H. Quesenberry 

University of Florida 

P.O. Box 110500 

Gainesville, FL 32611 

352-392-1811 

fax 352-392-1840 

clover@gnv.ifas.ufl.edu 

CC systems in Florida 

Jac Varco 

Mississippi State University 

Plant & Soil Sciences Dept. Box 9555 

Mississippi State, MS 39762 

662-325-2737 

fax 662-325-8742 

Jvarco@onyx.msstate.edu 

CC & fertilizer mgt. in no-till cotton production 

systems 


Michael G. Wagger 


Dept. of Soil Science 

P.O. Box 7619 

Raleigh, NC 27695-7619 

919-515-4269 

fax 919-515-2167 

michael_wagger@ncsu.edu 

nutrient cycling in CC based production systems 

WEST 

Miguel A. Altieri 

University of California at Berkeley 

215 Mulford Hall 

Berkeley, CA 94720-3112 

510-642-9802 

fax 510-642-7428 

agroeco3@nature.berkeley.edu 

http://nature.berkeley.edu/~agroeco3 

CC to enhance biological pest control in perennial 

systems 

Robert Bugg 

University of California at Davis 

159 DANR Building 

Davis, CA 95616 

530-754-8549 

fax 530-754-8550 

rlbugg@ucdavis.edu 

CC selection, growth & IPM 

David Chaney-SAREP Education 

Coordinator 



Davis, CA 95616-8716 

dechaney@ucdavis.edu 

530-754-8551 

fax 530-754-8550 

Ron Delaney 

University of Wyoming 

Dept. of Plant Sciences 

P.O. Box 3354 

Laramie,WY 82071-3354 

307-766-3103 

fax 307-766-5549 

rdelaney@uwyo.edu 

semi-arid annual legumes 

Richard Dick 

Oregon State University 

Dept. of Crop & Soil Science 

Ag and Life Sciences, Bldg 3067 

Corvallis, OR 97331 

541-737-5718 

fax 541-737-5725 

Richard.Dick@orst.edu 

nitrogen cycling & environmental applications of 

CC systems 

Charlotte Eberlein 

University of Idaho 

Twin Falls Research and Ext. Center 

317 Falls Avenue 

Twin Falls, ID 83303-1827 

208-736-3600 

fax 208-397-4311 

ceberl@uidaho.edu 

CC for weed control in potatoes 

Chuck Ingels 

UC Cooperative Extension 

4145 Branch Center Rd. 

Sacramento, CA 95827-3898 

916-875-6913 

fax 916-875-6233 

caingels@ucdavis.edu 

farm advisor-pomology, viticulture, 

& environmental horticulture 


Shiou Kuo 

Washington State University 

Research & Extension Center 

7612 Pioneer Way East 

Puyallup,WA 98371 

253-445-4573 

fax 253-445-4621 

Skuo@wsu.edu 

CC effects on soil, water quality and crop 

productivity 

John M. Luna 

Oregon State University 

Dept. of Horticulture 

4143 Agricultural and Life Sciences Bldg. 

Corvallis, OR 97331 

541-737-5430 

fax 541-737-3479 

lunaj@bcc.orst.edu 

CC for integrated vegetable production systems 

& agroecology 

Nancy Matheson 

3845 Hart Lane 

Helena, MT 59602 

406-227-9161 

406-227-0389 

nmatheson@imine.net 

Clara I. Nicholls 


Department of Environmental Science Policy 

and Management 

Division of Insect Ecology 

Berkeley, CA 94720 

510-642-9802 

fax 510-642-7428 

nicholls@uclink.berkeley.edu 

CC for biological control in vineyard systems 

James R. Sims 

21 Border Lane 

Bozeman, MT 59715 

tel/fax 406-582-1576 

dryland & alternate cropping systems 

Fred Thomas 

CERUS Consulting 

766 E.Avenue, 

#C 

Chico, CA 95926 

530-891-6958 

fax 530-891-5248 

ceruscon@aol.com 

CC systems specialist for all 

agricultural crops 

Dwain Meyer 

North Dakota State University 

Loftsgard Hall, Room 470E 

Extension Service 

Fargo, ND 58105 

701-231-8154 

dmeyer@ndsuext.nodak.edu 

yellow blossom sweet clover specialist 


APPENDIX G 

CITATIONS BIBLIOGRAPHY 

The publications cited in the text (in parentheses) are listed 

here by reference number. 

1 Abdul-Baki,Aref A. and John R.Teasdale. 1993.A 

no-tillage tomato production system using hairy 

vetch and subterranean clover mulches. 

HortSci. 28:106-108. 

2 Abdul-Baki,Aref and John R.Teasdale. 1997. 

Sustainable Production of Fresh-Market 

Tomatoes and Other Summer Vegetables with 

Organic Mulches. Farmers’ Bulletin No. 2279, 

USDA/ARS, Beltsville, Md. 23 pp. 

3 Alger, Jess. 1997. Personal communication. 

Stanford, Mont. 

4 American Forage and Grassland Council 

National Fact Sheet Series. Subterranean clover. 

http://forages.orst.edu/main.cfmPageID=33 

5 Anderson, Glenn. 1997. Personal 

communication. Hilmar, Calif. 

6 Angers, D.A. 1992. Changes in soil aggregation 

and organic carbon under corn and alfalfa. Soil 

Sci. Soc.Am. J. 56:1244-1249. 

7 Appropriate Technology Transfer for Rural 

Areas (ATTRA). 1991 Cover Crops and Green 

Manures. ATTRA. Fayetteville,Ark. 

8 Arshad, M.A. and K.S. Gill. 1996. Crop production, 

weed growth and soil properties under 

three fallow and tillage systems. J. Sustain.Ag. 

8:65-81. 

9 Badaruddin, M. and D.W. Meyer. 1989.Water use 

by legumes and its effects on soil water status. 

Crop Sci. 29:1212-1216. 

10 Badaruddin, M. and D.W. Meyer. 1990. Greenmanure 

legume effects on soil nitrogen, grain 

yield, and nitrogen nutrition of wheat. 

Crop Sci. 30:819-825. 

11 Bagegni,Ali. M. et al. 1994. Herbicides with 

crop competition replace endophytic tall fescue 

(Festuca arundinacae). Weed Tech. 8:689-695. 

12 Ball, Donald M. and Robert A. Burdett. 1977. 

Alabama Planting Guide for Forage Grasses. 

Alabama Cooperative Extension Service, Chart 

ANR 149.Auburn Univ.,Auburn,Ala. 

13 Ball, Donald M. and Robert A. Burdett. 1977. 

Alabama Planting Guide for Forage Legumes. 

Alabama Cooperative Extension Service, Chart 

ANR 150.Auburn Univ.,Auburn,Ala. 

14 Barker, Kenneth R. 1996.Animal waste, winter 

cover crops and biological antagonists for 

sustained management of Columbia lance and 

other nematodes on cotton. pp. 19-20. Southern 

Region 1996 Annual Report. Griffin, Ga. 

15 Barnes, Robert F. et al. 1995. Forages:The 

Science of Grassland Agriculture. 5th Edition. 

Iowa State Univ. Press,Ames, Iowa. 

16 Bauer, P.J. et al. 1993. Cotton yield and fiber 

quality response to green manures and nitrogen. 

Agron. J. 85:1019-1023. 

17 Bauer, P.J. 1997. Personal communication. 

USDA-ARS. Florence, S.C. 

18 Beale, P. et al. 1985. Balansa Clover—a New 

Clover-Scorch-Tolerant Species. South Australia 

Dept. of Ag. Fact Sheet. 

19 Beste, C. Edward. 1997. Personal 

communication. Univ. of Maryland-Eastern Shore, 

Salisbury, Md. 


20 Bird, George. 1997. Personal communication. 

Michigan State Univ. East Lansing, Mich. 

21 Bloodworth, L.H. and J.R. Johnson. 1995. 

Cover crops and tillage effects on cotton. J. Prod. 

Ag. 8:107-112. 

22 Bollich, P.K. 1997. Personal communication. 

Louisiana State Univ.. Crowley, La. 

23 Boquet, D.J. and S.M. Dabney. 1991. Reseeding, 

biomass, and nitrogen content of selected winter 

legumes in grain sorghum culture. Agron. J. 

83:144-148. 

24 Bowman, Greg. 1997. Steel in the Field:A 

Farmer’s Guide to Weed Management Tools. 

USDA-Sustainable Agriculture Network (SAN). 

Burlington,Vt. 

25 Bradley, John. 1997. Personal communication. 

Monsanto Crop Protection. Collierville,Tenn. 

26 Bradow, Judith M. and William J. Connick Jr. 

1990.Volatile seed germination inhibitors from 

plant residues. J. Chem. Ecol. 16:645-666. 

27 Bradow, Judith M. 1993. Inhibitions of cotton 

seedling growth by volatile ketones emitted by 

cover crop residues. J. Chem. Ecol. 19:1085-1108. 

28 Brady, Nyle C. 1990. The Nature and 

Properties of Soils. Macmillan Pub. Co., N.Y. 

29 Brandt, J.E., F.M. Hons and V.A. Haby. 1989. 

Effects of subterraneum clover interseeding on 

grain yield, yield components, and nitrogen 

content of soft red winter wheat. J. Prod.Agric. 

2:347-351. 

30 Brinsfield, R. and K. Staver. 1991. Role of cover 

crops in reduction of cropland nonpoint source 

pollution. Final Report to USDA-SCS, Cooperative 

Agreement #25087. 

31 Brinton,Will. Medics, general. Univ. of Calif. 

SAREP Cover Crops Resource Page. 

http://www.sarep.ucdavis.edu/ccrop/ 

32 Bruce, R.R, P.F. Hendrix and G.W. Langdale. 

1991. Role of cover crops in recovery and maintenance 

of soil productivity. pp.109-114. In W.L. 

Hargrove (ed.), Cover Crops for Clean Water.Soil 


33 Bruce, R.R. et al. 1992. Soil surface 

modification by biomass inputs affecting rainfall 

infiltration. Soil Sci. Soc.Am. J. 56:1614-1620. 

34 Brunson, K.E. 1991.Winter cover crops in 

the integrated pest management of sustainable 

cantaloupe production. M.S.Thesis. Univ. of 

Georgia,Athens, Ga. 

35 Brunson, K.E. and S.C. Phatak. 1990.Winter 

cover crops in low-input vegetable production. 

HortSci. 25:1158. 

36 Brunson, K.E., S.C. Phatak, L.D. Chandler and 

R.B. Chalfant. 1992.Winter cover crops influence 

insect populations in sustainable cantaloupe 

production. HortSci. 26:769. 

37 Brutlag,Alan. 1997. Personal communication. 

Wendell, Minn. 

38 Bugg, R.L. et al. 1990.Tarnished plant bug 

(hemiptera: Miridae) on selected cool-season 

leguminous cover crops. J. Entomol. 

Sci. 25:463-474. 

39 Bugg, R.L. et al. 1991. Cool season cover crops 

relay intercropped with cantaloupe: Influence of 

a generalist predator, Geocoris punctipes. J. Econ. 

Entomol. 84:408-416. 

40 Bugg, R.L. 1991. Cover crops and control of 

arthropod pests of agriculture. pp. 157-163. In 

Cover Crops for Clean Water (W.L. Hargrove, 

ed.). Proc. Int’l Conf.April 9-11, 1991.West 



41 Bugg, R.L. 1992. Using cover crops to manage 

arthropods on truck farms. HortSci. 27:741- 745. 

BIBLIOGRAPHY 181

42 Bugg, Robert L. and Carol Waddington. 1994. 

Using cover crops to manage arthropod pests of 

orchards:A review. Ag., Ecosystems & 

Env. 50:11-28. 

43 Bugg, Robert L. 1995. Cover biology: a minireview. 

SAREP Sustainable Agriculture-Technical 

Reviews. 7:4. Univ. of California, Davis, Calif. 

44 Bugg, Robert L. et al. 1996. Comparison of 32 

cover crops in an organic vineyard on the north 

coast of California. Biol.Ag. and Hort. 13:63-81. 

44.1 Bugg, Robert L., Robert J. Zomer and Jill S. 

Auburn. 1996. Cover crop profiles: One-page 

summaries describing 33 cover crops. In Cover 

Crops: Resources for Education and Extension 

(Chaney, David and Ann D. Mayse, eds). Univ. of 

California Sustainable Agriculture Research and 

Education Program (SAREP). Univ. of Calif., 

Division of Agriculture and Natural Resources, 

Davis, Calif. 

45 Bugg, Robert L. and Mark Van Horn. 1997. 

Ecological soil management and soil fauna: Best 

practices in California vineyards.Australian 

Society for Viticulture and Oenology, Inc. 

Proc.Viticulture Seminar, Mildura,Victoria, 

Australia. 

46 Burgos, Nilda R. and Ronald E.Talbert. 1996. 

Weed control by spring cover crops and 

imazethapyr in no-till southern pea (Vigna 

unguiculata). Weed Tech. 10:893-899. 

47 Buntin, G.D., J.N.All, D.V. McCracken and W.L. 

Hargrove. 1994. Cover crop and nitrogen fertility 

effects on southern corn rootworm (Coleoptera: 

Chrysomelidae) damage in corn. J. Econ. 

Entomol. 87:1683-1688. 

48 Butler, Lorna Michael. 1996. Fall-planted cover 

crops in western Washington:A model for sustainability 

assessment. Project Report #SW94- 

008.Western Region SARE. Logan, Utah. 

49 Campbell, C.A. et al. 1993. Influence of 

legumes and fertilization of deep distribution of 

available phosphorus in a thin black chernozemic 

soil. Can. Jour. Soil. Sci. 73:555-565. 

50 Campbell, C.A. et al. 1993. Spring wheat yield 

trends as influenced by fertilizer and legumes. 

J. Prod.Ag. 6:564-568. 

51 Canadian Organic Growers Inc. 1992. 

Organic Field Crop Handbook.Anne Macey (ed.). 

Canadian Organic Growers Inc., Ottawa, Ont. 

52 Cardina, John. 1997. Personal communication. 

Ohio State Univ.Wooster, Ohio. 

53 Cash, Dennis, Jim Sims, Howard Bowman and 

Bruce Smith. 1995. Growing Peas in Montana. 

Montguide MT 9520. Montana State Univ. 

Extension Service. Bozeman, Mont. 

54 Cathey, H. M. 1990. USDA Plant Hardiness 

Zone Map. USDA-ARS Misc. Pub. No. 1475. 

55 Chaney, David and D. Mays. March 1997. 

Cover Crops: Resources for Education and 

Extension. UC SAREP, Division of Agriculture and 

Natural Resources, Davis Calif. 

56 Chen, J., G.W. Bird. and R.L. Mather. 1995. 

Impact of multi-year cropping regimes on 

Solanum tuberosum tuber yields in the 

presence of Pratylenchus penetrans and 

Verticillium dahliae. J. Nematol. 27:654-660. 

57 Choi, B.H. et al. 1991.Acid amide, dinitroaniline, 

triazine, urea herbicide treatment and 

survival rate of coarse grain crop seedlings. 

Research Reports of the Rural Development 

Administration, Upland and Industrial Crops 

3:33-42. 

58 Christensen, Peter. 1997. Personal communication. 

Univ. of California. Davis, Calif. 


59 Clark,A.J. 1993. Managing hairy vetch/cereal 

rye cover crop mixtures for nitrogen and water 

in no-till corn. Ph.D. dissertation, Univ. of 

Maryland, College Park. Diss.Abstract 9407617. 

60 Clark,Andy. 1997. Personal communication. 

Sustainable Agriculture Network. USDA- SARE. 

Beltsville, Md. 

61 Clark,A. J. et al. 1994. Seeding rate and kill 

date effects on hairy vetch-cereal rye cover crop 

mixtures for corn production. Agron. J. 86: 

1065-1070. 

62 Clark,A.J. et al. 1995. Hairy vetch kill date 

effects on soil water and corn production. 

Agron. J. 87:579-585. 

63 Clark,A.J. et al. 1997a. Kill date of vetch, rye 

and a vetch-rye mixture: I. Cover crop and corn 

nitrogen. Agron. J. 89:427-434. 

64 Clark,A.J. et al. 1997b. Kill date of vetch, rye 

and a vetch-rye mixture: II. Soil moisture and 

corn yield. Agron. J. 89:434-441. 

65 Cooke, L. 1996. New Red Clover Puts Pastures 

in the Pink. USDA/ARS. 44:12 Washington, D.C. 

66 Costa, Jose. 1997. Personal communication. 

Univ. of Md. College Park, Md. 

67 Costello, Michael J. 1994. Broccoli growth, 

yield and level of aphid infestation in 

leguminous living mulches. Biol.Ag. and Hort. 

10:207-222. 

68 Crawford and Nankivell. Medics, general. Univ. 

of Calif. SAREP Cover Crops Resource Page. 


69 Creamer, Nancy G. 1997. Personal communication. 

North Carolina State Univ.. Raleigh, N.C. 

70 Creamer, Nancy G. et al. 1995.A method for 

mechanically killing cover crops to optimize 

weed suppression. Amer. J.Alt.Ag. 10:157-162. 

71 Creamer, Nancy G., Mark A. Bennett, Benjamin 

R. Stinner and John Cardina. 1996.A comparison 

of four processing tomato production systems 

differing in cover crop and chemical inputs. 

J.Amer. Soc. Hort. Sci. 121:559-568. 

72 Creamer, N.G., B. Plassman, M.A. Bennett, R.K. 

Wood, B.R. Stinner and J. Cardina. 1995.A method 

for mechanically killing cover crops to optimize 

weed suppression. Amer. J.Alt.Ag. 10:157-161. 

73 Cunfer, Barry M. 1996. Disease and insect 

management using new crop rotations for 

sustainable production of row crops in the 

Southern U.S. pp. 15-16. Southern Region 1996 

Annual Report. Griffin, Ga. 

74 Cruse, R.M. 1995. Potential economic, environmental 

benefits of narrow strip intercropping. 

Leopold Center Progress Reports 4:14-19. 

75 Dabney, Seth. 1996. Cover crop integration 

into conservation production systems. pp. 13-14. 

Southern Region 1996 Annual Report. 

Griffin, Ga. 

76 Dabney, S. M. 1995. Cover crops in reduced 

tillage systems. Proc. Beltwide Cotton 

Conferences. pp. 126-127. 5 Jan 1995. National 

Cotton Council, Memphis,Tenn. 

77 Dabney, Seth. 1997. Personal communication. 

USDA/ARS. Oxford, Miss. 

78 Dabney, S.M. and J.L. Griffin. 1987. Efficacy of 

burn down herbicides on winter legume cover 

crops. pp. 122-125. In Power, J.F. (ed.) The Role of 

Legumes in Conservation Tillage Systems. Soil 


79 Dabney, Seth et al. 1991. Mechanical control 

of legume cover crops. pp. 146-147. In Cover 

Crops for Clean Water (W.L. Hargrove, ed.). 

Proc. Int’l Conf.April 9-11, 1991.West Tennessee 

Experiment Station, Jackson,Tenn. Soil and Water 

Conservation Society.Ankeny, Iowa. 

BIBLIOGRAPHY 183

80 Davis, D.W. 1997. Personal communication. 

Univ. of Minnesota. St. Paul, Minn. 

81 Davis, D.W., et al. 1990. Cowpea. In 

Alternative Field Crops Manual. Univ. of 

Wisc-Ext. and Univ. of Minnesota. Madison,Wis. 

and St. Paul, Minn. 

82 Decker,A.M. 1997. Personal communication. 

Univ. of Maryland. College Park, Md. 

83 Decker,A.M.,A.J. Clark, J.J. Meisinger, F.R. 

Mulford and M.S. McIntosh. 1994. Legume cover 

crop contributions to no-tillage corn production. 

Agron. J. 86:126-136. 

84 Decker,A.M.,A.J. Clark, J.J. Meisinger, F.R. 

Mulford and V.A. Bandel. 1992. Winter Annual 

Cover Crops for Maryland Corn Production 

Systems.Agronomy Mimeo 34. Univ. of Md. 

Cooperative Ext. Service, Md. Inst. for Ag. and 

Natural Resources, College Park, Md. 

85 DeGregorio, R. et al. 1995. Bigflower vetch 

and rye vs. rye alone as a cover crop for no-till 

sweetcorn. J. Sustain.Ag. 5:7-18. 

86 DeWilde, R. 1997. Personal communication. 

Viroqua,Wis. 

87 Dick, Richard. 1997. Personal communication. 

Oregon State Univ.. Corvallis, Ore. 

88 Diver, Steve. 1997. Personal communication. 


(ATTRA). Fayetteville,Ark. 

89 Doll, Jerry. 1991. Cited in Shirley, C.D. No-till 

beans: rye not! The New Farm. 13:12-15. 

90 Doll, J. and T. Bauer. 1991. Rye: more than a 

mulch for weed control. pp. 146-149. Illinois 

Agricultural Pesticides Conference presentation 

summaries. Urbana, Ill. 

91 Duke, James A. 1981. Handbook of Legumes 

of World Economic Importance. Plenum Press, 

N.Y. 

92 Earhart, D.R. 1996. Managing soil phosphorus 

accumulation from poultry litter application 

through vegetable/legume rotations. Project 

Report #LS95-69. pp. 33-34. Southern Region 

1996 Annual Report. Griffin, Ga. 

93 Eberlein, Charlotte. 1995. Development of 

winter wheat cover crop systems for weed 

control in potatoes. Project Report #LW91-27. 

Western Region SARE. Logan, Utah. 

94 Eckert, D.J. 1991. Chemical attributes of soils 

subjected to no-till cropping with rye cover 

crops. Soil Sci. Soc.Am. J. 55:405-409. 

95 Edwards,W.M. et al. 1993.Tillage studies with 

a corn-soybean rotation: Hydrology and sediment 

loss. Soil Sci. Soc.Am. J. 57:1051-1055. 

96 Einhellig, F.A. and J.A. Rasmussen. 1989. Prior 

cropping with grain sorghum inhibits weeds. 

J. Chem. Ecol. 15:951-960. 

97 Einhellig, F.A. and I.F. Souze. 1992.Allelopathic 

activity of sorgoleone. J. Chem. Ecol. 18:1-11. 

98 Enache,A.J., R.D. Ilnicki and R.R. 

Helberg.1992. Subterranean clover living mulch: 

A system approach. pp. 160-162. In Proc. First 

Int’l Weed Control Congress, Vol. 2. February 

17- 21, 1992.Weed Science Society of Victoria, 

Melbourne,Australia. 

99 Enache,A.J. 1990.Weed control by subterranean 

clover (Trifolium subterraneum L.) used 

as a living mulch. Dissertation Abstracts Int., Sci. 

and Eng., 1990, 50(11):4825B. 

100 Fairbrother,T.E. 1991. Effect of fluctuating 

temperatures and humidity on the softening rate 

of hard seed of subterranean clover (Trifolium 

subterraneum L.). Seed Sci.Tech. 19:93-105. 

101 Fairbrother,T.E. 1997. Softening and loss of 

subterranean clover hard seed under sod and 

bare ground environments. Crop. Sci. 37:839-844. 


102 Fernholz, Carmen. 1997. Personal communication. 

Madison, Minn. 

103 Finch Univ. of Calif. Medics, general. 



104 Fisk, J.W. and O.B. Hesterman. 1996. N 

contribution by annual legume cover crops for 

no-till corn. In 1996 Cover Crops Symposium 

Proceedings. Michigan State Univ.,W.K. Kellogg 

Biological Station, Battle Creek, Mich. 

105 Fischer,Albert and Larry Burrill. 1993. 

Managing interference in sweet corn-white 

clover living mulch system. Am. J.Alt.Ag. 8:51-56. 

106 Fisk, J.W. 1997. Personal communication. 

Michigan State Univ.. East Lansing, Mich. 

107 Flexner. 1990. Hairy vetch. Univ. of Calif. 



108 Folorunso, Olatunji et al. 1992. Cover crops 

lower soil surface strength, may improve soil 

permeability. Calif.Ag. 46:26-27. 

109 Forney, D. Raymond and Chester L. Foy. 

1984. Phytotoxicity of products from rhizospheres 

of a sorghum-sudangrass hybrid. Weed 

Sci. 33:597-604. 

110 Forney, D. Raymond et al. 1985.Weed 

suppression in no-till alfalfa (Medicago sativa) 

by prior cropping of summer-annual forage 

grasses. Weed Sci. 33:490-497. 

111 Fortin, M.C. and A.S. Hamill. 1994. Rye 

residue geometry for faster corn development. 

Agron. J. 86:238-243. 

112 Foster, R.K. 1990. Effect of tillage implement 

and date of sweetclover incorporation on 

available soil N and succeeding spring wheat 

yields. Can. J. Plant Sci. 70:269-277. 

113 Fox, R.H. and W.P. Piekielek. 1988. Fertilizer 

N equivalence of alfalfa, birdsfoot trefoil, and red 

clover for succeeding corn crops. J. Prod.Agric. 

1:313-317. 

114 Friedman, Diana et al.1996. Evaluation of five 

cover crop species or mixes for nitrogen production 

and weed suppression in Sacramento Valley 

farming systems. Univ. of California Cover Crop 

Research and Education Summaries. 1994- 

1996. Davis, Calif. 

115 Friesen, G.H. 1979.Weed interference 

in transplanted tomatoes (Lycopersicon 

esculentum).Weed Sci. 27:11-13. 

116 Gardner, John ( ed.). 1992. Substituting 

legumes for fallow in U.S. Great Plains wheat 

production:The first five years of research and 

demonstration 1988-1992. USDA/SARE and 

North Dakota State Univ., Michael Fields 

Agricultural Institute, Kansas State Univ. and 

Univ. of Nebraska. NDSU Carrington Research 

Extension Center, Carrington, N.D. 

117 Geneve, R.L. and L.A.Weston. 1988. Growth 

reduction of Eastern redbud (Cercis canadensis 

L.) seedlings caused by interaction with a 

sorghum-Sudangrass hybrid (Sudax). 

J. Env. Hort. 6:24-26. 

118 Ghaffarzadeh, M. 1994. Progress Report: 

Berseem Clover (Trifolium alexandrinum L.). 

17 pp. Soil Management,Agronomy Department, 

Iowa State Univ.,Ames, Iowa. 

119 Ghaffarzadeh, M. 1995. Considering annual 

clover Don’t overlook berseem. Pub. #SA-7. 4 

pp. Sustainable Agriculutre Fact Sheet Series.The 

Leopold Center,Ames, Iowa. 

120 Ghaffarzadeh, M. 1996. Forage-based beef 

production research at the Armstrong Outlying 

Research farm.Annual research report.A. S. 

Leaflet R1245. Iowa State Univ.,Ames, Iowa. 

BIBLIOGRAPHY 185

121 Ghaffarzadeh, M. 1997.Annual legume makes 

comeback. pp. 24-25. Beef Today. January, 1997. 

122 Ghaffarzadeh, M. 1997. Economic and biological 

benefits of intercropping berseem clover 

with oat in corn-soybean-oat rotations. J. Prod.Ag. 

10:314-319. 

123 Ghaffarzadeh, M. 1995. Potential uses of 

annual berseem clover in livestock production. 

Proc. Rotational Grazing, a conference sponsored 

by The Leopold Center for Sustainable 

Agriculture, Feb. 5-6, 1995. Published by Iowa 

State Univ. Extension. See also Demonstration of 

an annual forage crop integrated with crop and 

livestock enterprises. In Progress Report. March 

1998.The Leopold Center for Sustainable 

Agriculture 7:6-10. 

124 Ghaffarzadeh, M. 1997. Personal communication. 

Iowa State Univ.Ames, Iowa. 

125 Goldstein,Walter. 1997. Personal communication. 

Michael Fields Agricultural Institute. 

East Troy,Wis. 

126 Granzow, Bill and Delores. 1997. Personal 

communication. Herington, Kan. 

127 Graves,Walter L. et al. 1996. Berseem Clover: 

A Winter Annual Forage for California 

Agriculture. Univ. of California, SAREP. Div. of 

Agriculture and Natural Resources. Pub. 21536. 

Davis, Calif. 

128 Green, B.J. and V.O. Biederbeck. 1995. 

Farm Facts: Soil Improvement with Legumes, 

Including Legumes in Crop Rotations. 

Canada-Saskatchewan Agreement on Soil 

Conservation, Regina, SK. 

129 Greene, D.K. et al.1992. Research report. 

New Crop News.Vol. 3. Purdue Univ.,West 

Lafayette, Ind. 

130 Griffin, J.L. and S.M. Dabney. 1990. Preplantpostemergence 

herbicides for legume cover-crop 

control in minimum tillage systems. Weed Tech. 

4:332-336. 

131 Groff, Steve. 1997. Cedar Grove Farm. 

http://www.cedarmeadowfarm.com 

132 Groff, Steve. 1997. Personal communication. 

Holtwood, Pa. 

133 Grubinger,Vernon P. and Peter L. Minotti. 

1990. Managing white clover living mulch for 

sweet corn production with partial rototilling. 

Amer. J.Alt.Ag. 5:4-11. 

134 Geunther, Paul. 1997. Personal 

communication. Dexter, Mich. 

135 Guy, Stephen. 1997. Personal 

communication. Univ. of Idaho. Moscow, Idaho. 

136 Hanson, J.C., E. Lichtenberg,A.M. Decker and 

A.J. Clark. 1993. Profitability of no-tillage corn 

following a hairy vetch cover crop. J. Prod.Ag. 

6:432-436. 

137 Hanson, James C. et al. 1997. Organic 

versus conventional grain production in the 

mid-Atlantic:An economic and farming system 

overview. Amer. J.Alt.Ag.12:2-9. 

138 Harlow, Susan. 1994. Cover crops pack 

plenty of value. Amer.Agriculturalist 191:14. 

139 Harper, L.A., P.F. Hendrix, G.W. Langdale and 

D.C. Coleman. 1995. Clover management to 

provide optimum nitrogen and soil water 

conservation. Crop Sci. 35:176-182. 

140 Harwood, Richard , M. Jones,T.Willson, J. 

Smeenk. 1996. Cover crop effects on nitrogen 

cycling—a summary. pp. 10-11. Proc. Cover Crop 

Symposium. Jan. 4-5, 1996, Michigan State Univ., 

W.K. Kellogg Biological Station. Hickory Corners, 

Mich. 


141 Helm, J.L. and Dwain Meyer. 1993. 

Sweetclover production and management. 

North Dakota Extension Service Publication 

R-862. Fargo, N.D. 

142 Hendricks L.C. 1995.Almond growers 

reduce pesticide use in Merced County field 

trial. Calif.Ag. 49:5-10. 

143 Hermel, Rose. 1997. Forage Focus:Annual 

legume makes comeback. pp. 24-25. Beef. 

January, 1997. 

144 Hiltbold,A.E.1991.Nitrogen-fixing bacteria 

essential for crimson clover.Alabama Agricultural 

Experiment Station 38:13.Auburn,Ala. 

145 Hoffman, Melinda L. et al. 1993.Weed and 

corn responses to a hairy vetch cover crop. 

Weed Tech. 7:594-599. 

146 Hoffman, Melinda L. et al. 1996. Interference 

mechanisms between germinating seeds and 

between seedlings: Bioassays using cover crop 

and weed species. Seed Sci. 44:579-584. 

147 Hofstetter, Bob. 1988. The New Farm’s cover 

crop guide: 53 legumes, grasses and legumegrass 

mixes you can use to save soil and money. 

The New Farm 10:17-22, 27-31. 

148 Hofstetter, Bob. 1992. Bank on buckwheat. 

The New Farm 14:52-53. 

149 Hofstetter, Bob. 1992. How sweet it is: 

Yellow-blossom sweetclover fights weeds, adds N 

and feeds livestock. The New Farm 14:6-8. 

150 Hofstetter, Bob. 1992. Reliable ryegrass. The 

New Farm 14:54-55, 62. 

151 Hofstetter, Bob. 1993a. Meet the queen of 

cover crops. The New Farm 15:37-41. 

152 Hofstetter, Bob. 1993b. Fast and furious. The 

New Farm 15:21-23, 46. 

153 Hofstetter, Bob. 1993c. Red clover revival. 


154 Hofstetter, Bob. 1993d.A quick & easy cover 

crop. The New Farm 15:27-28. 

155 Hofstetter, Bob. 1993e. Reconsider the lupin. 


156 Hofstetter, Bob. 1994a.The carefree cover. 


157 Hofstetter, Bob. 1994b. Bring on the medics! 

The New Farm 16:56, 62. 

158 Hofstetter, Bob. 1994c.Warming up to 

winter peas. The New Farm 16:11-13. 

159 Hofstetter, Bob. 1995. Keep your covers in 

the pink. The New Farm 17:8-9. 

160 Holderbaum, J.F. et al.1990. Fall-seeded 

legume cover crops for no-tillage corn in the 

humid East. Agron. J. 82:117-125. 

161 Holle, Oren. 1995. Compare the agronomic 

and economic benefits of 3 or 4 annual alfalfa 

varieties to sweetclover for forage and soil building 

purposes in a feed grain, soybeans, wheat/ 

legume rotation. Project Report #FNC92-4. 

North Central Region SARE. Lincoln, Neb. 

162 House and Alzugaray. 1989. Hairy vetch. 

Univ. of Calif. SAREP Cover Crops Resource Page. 


163 Howieson and Ewing. 1989. Medics, general. 



164 Hoyt, G.D. and W.L. Hargrove. 1986. Legume 

cover crops for improving crop and soil 

management in the southern United States. 

HortSci. 21:397-402. 

165 Illnicki, R.D. 1997. Personal communication. 

Rutgers Univ.. New Brunwick, N.J. 

BIBLIOGRAPHY 187

166 Ingels, Chuck A. et al. 1994. Selecting the 

right cover crop gives multiple benefits. 

Calif.Ag. 48:43-48. 

167 Ingels, Chuck A. 1995. Cover cropping in 

vineyards.Amer.Vineyard. 6/95, 8/95, 9/95, 10/95. 

In Chaney, David and Ann D. Mayse (eds.). 1997. 

Cover Crops: Resources for Education and 

Extension. Univ. of California, Div. of Agriculture 

and Natural Resources, Davis, Calif. 

168 Ingels, Chuck A. 1997. Personal 

communication. Univ. of California. Davis, Calif. 

169 Ingels, Chuck A. et al. 1994. Selecting the 

right cover crop gives multiple benefits. 

Calif.Ag. 48:43-48. 

170 Ingels, Chuck A. et al. 1996. Univ. of 

California Cover Crop Research & Education 

Summaries, March 1996. UC SAREP, Davis, Calif. 

171 Iyer, J.G., S.A.Wilde and R.B. Corey. 1980. 

Green manure of sorghum-sudan: Its toxicity to 

pine seedlings. Tree Planter’s Notes 31:11-13. 

172 Izaurralde, R.C. et al. 1990. Plant and nitrogen 

yield of barley-field pea intercrop in 

cryoboreal-subhumid central Alberta. 

Agron. J. 82:295-301. 

173 Jackson, Louise E. 1995. Cover crops incorporated 

with reduced tillage on semi-permanent 

beds: Impacts on nitrate leaching, soil fertility, 

pests and farm profitability. Project Report 

#AW92-06.Western Region SARE. Logan, Utah. 

174 Jacobs, Eleanor. 1995. Cover crop breathes 

life into old soil: Sorghum-sudangrass, used as an 

onion rotation crop on organic soils, cuts pesticide 

costs, rejuvenates soil and increases yields. 

Amer.Agriculturist 192:8. 

175 Jensen, E.S. 1996. Barley uptake of N 

deposited in the rhizosphere of associated 

field pea. Soil. Biol. Biochem. 28:159-168. 

176 Johnson, Lance. Personal communication. 

Hesperia, Mich. 

177 Jordan, Jeffrey L. et al. 1994. An Economic 

Analysis of Cover Crop Use in Georgia to 

Protect Groundwater Quality. Research Bulletin 

#419. Univ. of Georgia, College of Agric. and 

Environ. Sciences,Athens, Ga. 13 pp. 

178 Kelly,Terry C. et al. 1995. Economics of a 

hairy vetch mulch system for producing freshmarket 

tomatoes in the Mid-Atlantic region. 

J.Amer. Soc. Hort. Sci. 120:854-869. 

179 Kimbrough, E. Lamar and William E. Knight. 

Forage ‘Bigbee’ Berseem Clover. Mississippi State 

Univ. Extension Service. Online at 

http://ext.msstate.edu/pubs/is1306.htm 

180 King, Larry D. 1988. Legumes for nitrogen 

and soil productivity. Stewardship News 8:4-6. 

181 Kirchmann, H. and H. Marstop. 1992. 

Calculation of N mineralization from six green 

manure legumes under field conditions from 

autumn to spring. Acta Agriculturae Scand. 

41:253- 258. 

182 Knight. 1985. Crimson clover. Univ. of Calif. 



183 Knorek, Jack and Mike Staton. 1996.“Red 

Clover.” Cover Crops:MSU/KBS (fact sheet packet), 

Michigan State Univ. Extension, East Lansing, 

Mich. 

184 Koch, David W. 1995. Brassica utilization in 

sugarbeet rotations for biological control of cyst 

nematode. Project Report #LW91-22.Western 

Region SARE. Logan, Utah. 

185 Koike, S.T. et al. 1996. Phacelia, Lana woollypod 

vetch and Austrian winter pea: three new 

cover crop hosts of Sclerotina minor in 

California. Plant Dis. 80:1409-1412. 


186 Koume, C.N. et al. 1988. Screening 

subterranean clover (Trifolium spp.) germplasm 

for resistance to meloidogyne species. J.Nematol. 

21(3):379-383. 

187 Kumwenda, J.D.T., D.E. Radcliffe,W.L. 

Hargrove and D.C. Bridges. 1993. Reseeding of 

crimson cover and corn grain yield in a living 

mulch system. Soil Sci. Soc.Am. J. 57:517-523. 

188 Langdale, G.W. and W.C. Moldenhauer (eds). 

1995. Crop Residue Management to Reduce 

Erosion and Improve Soil Quality. USDA-ARS, 

Conservation Research Report No. 39. 

Washington, D.C. 

189 Lanini,W.T. et al. 1989. Subclovers as living 

mulches for managing weeds in vegetables. 

Calif.Agric. 43:25-27. 

190 Leach, S.S. 1993. Effects of moldboard plowing, 

chisel plowing and rotation crops on the 

Rhizoctonia disease of white potato. American 

Potato Journal 70:329-337. 

191 LeCureux, James P. 1996. Integrated system 

for sustainability of high-value field crops. Project 

Report #LNC94-64. North Central Region SARE. 

Lincoln, Neb. 

191.1 Leroux,G.D.et al.1996.Effect of crop rotations 

in weed control,Bidens cernua and Erigeron 

canadensis populations,and carrot yields in organic 

soils.Crop Protection 15:171-178. 

192 Lichtenberg, E., J.C. Hanson,A.M. Decker and 

A.J. Clark. 1994. Profitability of legume cover 

crops in the mid-Atlantic region. J. Soil Water 

Cons. 49:582-585. 

193 Linn, D.M. and J.W. Doran. 1984. Effect of 

water-filled pore space on carbon dioxide and 

nitrous oxide production in tilled and nontilled 

soil. Soil Sci. Soc.Am. J. 48:1267-1272. 

194 LiphaTech. 1997. Personal communication. 

Milwaukee,Wis. 

195 Liu, D.L. and J.V. Lovett. 1994. Biologically 

active secondary metabolites of barley. I. 

Developing techniques and assessing allelopathy 

in barley. J. Chem. Ecol. 19:2217-2230. 

196 Liu, D.L. and J.V. Lovett. 1994. Biologically 

active secondary metabolites of barley. II. 

Phytotoxicity of barley allelochemicals. J. Chem. 

Ecol. 19:2231-2244. 

197 Lovett, J.V. and A.H.C. Hoult. 1995. 

Allelopathy and self-defense in barley. pp. 170- 

183. In Allelopathy: Organisms, Processes, and 

Applications. American Chemical Society, 

Washington, D.C. 

198 MacGuidwin,A.E. and T.L. Layne. 1995. 

Response of nematode communities to sudangrass 

and sorghum-sudangrass hybrids grown as 

green manure crops. J. Nematol. 27:609- 616. 

199 Maddox, Erol. 1997. Personal 

communication. Hebron, Md. 

200 Mackay. 1981. Medics, general. Univ. of Calif. 



201 Mahler, R.L. 1989. Evaluation of the green 

manure potential of Austrian winter pea in 

northern Idaho. Agron. J. 81:258-264. 

202 Mahler, R.L. 1993. Evaluation of the nitrogen 

fertilizer value of plant materials to spring wheat 

production. Agron J. 85:305-309. 

203 Malik, N. and J.Waddington. 1988. Polish 

rapeseed as a companion crop when 

establishing sweetclover for dry matter 

production. Can. J. Plant. Sci. 68:1009-1015. 

204 Marks and Townsend. 1973. Buckwheat. 



205 Martin,Todd. 1997. Personal communication. 

Michigan State Univ.W.K. Kellogg Biological 

Station, Hickory Corners, Mich. 

BIBLIOGRAPHY 189

206 Marshall, H.G. and Y. Pomeranz. 1982. 

Buckwheat: description, breeding, production 

and utilization. pp. 157-210. In Advances in 

Cereal Science and Technology (Y. Pomeranz, 

ed.).Amer.Assn. of Cereal Chemists, Inc., 

St. Paul, Minn. 

207 Matthews,Allen. 1997.Alternative rotation 

system for vegetables. Project Report #FNE96- 

146. Northeast Region SARE. Burlington,Vt. 

208 Matthews,Allen. 1997. Personal 

communication. Scenery Hill, Pa. 

209 McCraw, Dean et al. 1995. Use of Legumes 

in Pecan Orchards. Oklahoma Cooperative 

Extension Service. Current Report CR-06250, 4 

pp. Stillwater, OK. 

210 McGuire, C.F. et al. 1989. Nitrogen contribution 

of annual legumes to the grain protein content of 

‘Clark’ barley (Hordeum disticum L.) production. 

Applied Ag. Res. 4:118-121. 

211 McLeod. Medics, general. Univ. of Calif. 



212 McSorley, R. and R.N. Gallagher. 1994. Effect 

of tillage and crop residue management on 

nematode densities on corn. J. Nematol. 

26:669-674. 

213 Meisinger, J.J. et al.1991. Effects of cover 

crops on groundwater quality. pp. 57-68. In 

Cover Crops for Clean Water (W.L. Hargrove, 

ed.). Proc. Int’l Conf.April 9-11, 1991.West 



214 Meyer, Dwain. 1997. Personal communication. 

North Dakota Extension Service. Fargo, N.D. 

215 Meyer, D.W. and W.E. Norby. 1994. Seeding 

rate, seeding-year harvest, and cultivar effects on 

sweetclover productivity. North Dakota Farm 

Res. 50:30-33. 

216 Michigan State Univ. Extension. 1996. Cover 

Crops: MSU/KBS (factsheet packet).“Cover 

Crops General Information,”“Cover Crop Seeding 

Methods and Equipment,”“Managing Cover 

Crops in Michigan,”“Red Clover,”“Annual 

Medics,”“Sources of Cover Crop Seed for 

Michigan.” MSU. East Lansing, Mich. http://www. 

kbs.msu.edu/extension/Covercrops/home.htm 

217 Michigan State Univ.. 1996. Cover Crops 

Symposium Proceedings. Michigan State Univ., 

W.K. Kellogg Biological Station, Battle Creek, 

Mich. 

218 Miller, Michelle M. 7/21/97. Reduced input, 

diversified systems. Press release via electronic 

transmission from Univ. of Wisconsin Extension- 

Agronomy, Madison,Wis. 

219 Miller, P.R. et al. 1989. Cover Crops for 

California Agriculture. University of California, 

SAREP. Div. of Agriculture and Natural Resources. 

Davis, Calif. 24 pp. 

220 Miller, M.H. et al.1994. Leaching of nitrogen 

and phosphorus from the biomass of three cover 

crops. J. Environ. Qual. 23:267-272. 

221 Miller, 1989. Medics, general. Univ. of Calif. 



222 Millhollon, E.P. 1994.Winter cover crops 

improve cotton production and soil fertility in 

Northwest Louisiana. La.Ag. 37:26-27. 

223 Mishanec, John. 1996. Use of sorghumsudangrass 

for improved yield and quality of 

vegetables produced on mineral and muck 

soils in New York: Part II—Sudan trials on 

muck soils in Orange County. Research report. 

Cornell Cooperative Extension. Ithaca, N.Y. 

224 Mishanec, John. 1997. Personal 

communication. Ithaca, N.Y. 

225 Mississippi State Univ. website. 

http://ext.msstate.edu/pubs/ 


226 Mohler, Charles L. 1994.A living mulch 

(white clover)/dead mulch (compost) weed 

control system for winter squash. Unpublished 

research paper. Ecology and Systematics, 

Cornell Univ., Ithaca, NY. 

227 Mojtahedi, H. et al. 1993. Suppression of 

Meloidogyne chitwoodi with sudangrass cultivars 

as green manure. J. Nematol. 25:303-311. 

228 Moomaw, R.S. 1995. Selected cover crops 

established in early soybean growth stage. J. Soil 

and Water Cons. 50:82-86. 

229 Moore, Steve. 1997. Personal 

communication. Center for Sustainable Living. 

Wilson College. Chambersburg, Pa. 

230 Moyer, Jeff. 1997. Personal communication. 

Rodale Institute Experimental Farm. 

Kutztown, Pa. 

231 Moynihan, J.M. et al. 1996. Intercropping 

barley and annual medics. In Cover Crops 

Symposium Proceedings. Michigan State Univ., 

W.K. Kellogg Biological Station, Battle Creek, 

Mich. 

232 Muehlbauer, Frederick L. 1997. Personal 

communication.Washington State Univ. Pullman, 

Wash. 

233 Munoz, Faustino N. 1987. Legumes for 

Orchard, Vegetable and Cereal Cropping 

Systems. Coop. Ext., Univ. of California, San 

Diego, Calif. 

234 Munoz, F.N. 1988. Medics, general. Univ. of 

Calif. SAREP Cover Crops Resource Page. 


235 Munoz, Faustino N. and Walter Graves. 

Medics, general. Univ. of Calif. SAREP Cover 

Crops Resource Page. 


236 Murphy,A.H. et al. 1976. Medic, bur. Univ. of 



237 Murray, Glen A. 1997. Personal 

communication. Univ. of Idaho. Moscow, Idaho. 

238 Mutch, D.R., Gary L. Zehr,Todd E. Martin and 

Tim Duckert. 1996. Evaluation of low-input corn 

system. In Cover Crops Symposium Proceedings. 

Michigan State Univ.,W.K. Kellogg Biological 

Station. Battle Creek, Mich. 

239 Mutch, D.R. et al. 1996. Evaluation of overseeded 

cover crops at several corn growth stages 

on corn yield. In Cover Crops Symposium 

Proceedings. Michigan State Univ.,W.K. Kellogg 

Biological Station, Battle Creek, Mich. 

240 Mutch, Dale R. 1997. Personal 

communication. Michigan State Univ. Hickory 

Corners, Mich. 

241 Mwaja,V.N., J.B. Masiunas and C.E. Eastman. 

1996. Rye and hairy vetch intercrop 

management in fresh-market vegetables. 

J.Amer. Soc Hort. 121:586-591. 

242 Myers, Robert L. and Louis J. Meinke. 1994. 

Buckwheat:A Multi-Purpose, Short-Season 

Alternative. MU Guide G 4306. Univ. Extension, 

Univ. of Missouri-Columbia. 

243 Nafziger, E.D. 1994. Corn planting date and 

plant population. J. Prod.Agric. 7:59-62. 

244 National Assn.of Wheat Growers Foundation. 

1995.Best Management Practices for Wheat:A 

Guide to Profitable and Environmentally Sound 

Production.National Assn.of Wheat Growers 

Foundation.Washington,D.C. 

245 Nimbal, C.I., J. Pederson, C.N.Yerkes, L.A. 

Weston and S.C.Weller. 1996. Phytotoxicity and 

distribution of sorgoleone in grain sorghum 

germplasm. J.Agric. Food Chem. 44:1343-1347. 

BIBLIOGRAPHY 191

246 Ocio, J.A. et al. 1991. Field incorporation of 

straw and its effects on soil microbial biomass and 

soil inorganic N. Soil Biol. Biochem. 23:171-176. 

247 Oekle, E.A. et al. 1990. Rye. In Alternative 

Field Crops Manual. Univ. of Wisc-Ext. and Univ. 

of Minnesota, Madison,Wis. and St. Paul, Minn. 

248 Orfanedes, Michael S. et al. 1995. Sudangrass 

trials—What have we learned to date Cornell 

Cooperative Extension Program, Lake Plains 

Vegetable Program. 

249 Oregon State Univ. website,“Forage 

Information System” 

http://forages.orst.edu/main.cfmPageID=33 

250 Ott, S.L. and W.L. Hargrove. 1989. Profit and 

risks of using crimson clover and hairy vetch 

cover crops in no-till corn production. Amer. 

J.Alt.Ag. 4:65-70. 

251 Paine,Laura et al.1995.Establishment of 

asparagus with living mulch.J.Prod.Agric. 8:35-40. 

252 Parkin,T.B.,T.C. Kaspar and C.A. 

Cambardella.1997. Small grain cover crops to 

manage nitrogen in the Midwest. Proc. Cover 

Crops, Soil Quality, and Ecosystems Conference. 

March 12-14, 1997. Sacramento, Calif. Soil and 

Water Conservation Society,Ankeny, Iowa. See 

also related paper in J. Soil Water Cons. (Summer 

1998). In press. 

253 Pennsylvania Sustainable Agriculture 

Association (PASA). 1993. Using legume cover 

crops as a nitrogen source for cash grains. 

pp. 20-21. Pennsylvania Sustainable Agriculture 

Project. Millheim, Pa. 

254 Paxton, J.D. and J. Groth. 1994. Constraints 

on pathogens attacking plants. Critical Rev. Plant 

Sci. 13:77-95. 

255 Paynter, B. H. Medics, general. Univ. of Calif. 



256 Peaceful Valley Farm Supply. 1997. Personal 

communication. Phil Radspinner and Laura 

Kibilewski. Grass Valley, Calif. 

257 Peet, Mary. 1995. Sustainable Practices for 

Vegetable Production in the South. Summer 

annuals and winter annuals lists. 

http://www2.ncsu.edu/ncsu/cals/sustainable/peet/ 

258 Pennington, Brooks. 1997. Seeds & Planting 

(3rd Ed.) Pennington Seed, Inc., Madison, Ga. 

259 Phatak, S.C. 1987a.Tillage and fertility management 

in vegetables. Amer.Vegetable Grower 

35:8-9. 

260 Phatak, S.C. 1987b. Integrating methods for 

cost effective weed control. Proc. Integ.Weed 

Manag. Symp. Expert Committee on Weeds. 

Western Canada. 65 p. 

261 Phatak, S.C. 1992.An integrated sustainable 

vegetable production system. HortSci. 27:738- 741. 

262 Phatak, S.C. 1993. Legume cover crops-cotton 

relay cropping systems. Proc. Organic Cotton 

Conf. pp. 280-285. Compiled and edited by 

California Institute for Rural Studies, P.O. Box 

2143, Davis, Calif. 95617. 

263 Phatak, S.C. 1997. Personal communication. 

Univ. of Georgia.Athens, Ga. 

264 Phatak, S.C., R. L. Bugg, D. R. Sumner, J. D. 

Gay, K. E. Brunson and R. B. Chalfant. 1991. Cover 

crops effects on weeds diseases, and insects of 

vegetables. pp. 153-154. In Cover Crops for 

Clean Water (W.L. Hargrove, ed.). Proc. Int’l Conf. 

April 9-11, 1991.West Tennessee Experiment 

Station, Jackson,Tenn. Soil and Water 

Conservation Society.Ankeny, Iowa. 

265 Pieters,A. J. 1927. Green Manuring. John 

Wiley & Sons, N.Y. 

266 Pledger, D. J., and D. J. Pledger, Jr. 1951. 

Cotton culture on Hardscramble Plantation. 

Hardscramble Plantation. Shelby, Miss. 


267 Plumer, Mike. 1997. Personal communication. 

Illinois State Univ. Cooperative Extension 

Service. Salem, Ill. 

268 Porter, Steve. 1994. Increasing options 

for cover cropping in the Northeast. Project 

Report #FNE93-14. Northeast Region SARE. 


269 Porter, Steve. 1995. Increasing options 

for cover cropping in the Northeast. Project 

Report #FNE94-66. Northeast Region SARE. 


270 Power, J.F. 1991. Growth characteristics of 

legume cover crops in a semiarid environment. 

Soil Sci. Soc.Am. J. 55:1659-1663. 

271 Power, J.F. 1994. Cover crop production for 

several planting and harvest dates in eastern 

Nebraska. Agron J. 86:1092-1097 

272 Power, J.F. et al. 1991. Hairy vetch as a winter 

cover crop for dryland corn production. 

J. Prod.Ag. 4:62-67. 

273 Power, J.F. and J.A. Zachariassen. 1993. 

Relative nitrogen utilization by legume cover 

crop species at three soil temperatures. 

Agron. J. 85:134-140. 

274 Premium Seed Company, Inc. 1997. Forage 

Seed Catalog. Shakopee, Minn. 

275 Przepiorkowski,T. and S.F. Gorski. 1994. 

Influence of rye (Secale cereale) plant residues 

on germination and growth of three triazineresistant 

and susceptible weeds. Weed Technol. 

8:744-747. 

276 Quesenberry, K.H., D.D. Baltensperger and 

R.A. Dunn. 1986. Screening Trifolium spp. for 

response to Meloidogyne spp. 

Crop Sci. 26:61-64. 

278 Quinlivan, B.J. et al. Medics, general. Univ. of 



279 Rajalahti, R.M. and R.R. Bellinder. 1996. 

Potential of interseeded legume and cereal cover 

crops to control weeds in potatoes. pp. 349-354. 

Proc. 10th Int. Conf. On Biology of Weeds, Dijon, 

France. 

280 Rajalahti, R., and R.R. Bellinder. 1997.Time 

of hilling and interseeding of cover crop influences 

weed control and yield of potato. WSSA 

Abstracts 1997. Meeting of the Weed Science 

Society of America. February 3-6, 1997,Vol. 37, 

Abstract 50, p. 21. 

281 Cambra, Chuck. 1997. Personal communication. 

Kamprath Seed Company, Manteca, Calif. 

282 Ranells, Noah N. 1997. Personal communication. 

North Carolina State Univ. Raleigh, N.C. 

283 Ranells, Noah N. and Michael G.Wagger. 

1993. Crimson clover management to enhance 

reseeding and no-till corn grain production. 

Agron. J. 85:62-67. 


1996. Nitrogen release from grass and legume 

cover crop monocultures and bicultures. 

Agron. J. 88:777-782. 


1997. Grass-legume bicultures as winter annual 

cover crops. Agron. J. 89:659-665. 

286 Reddy, K.N., M.A. Locke, C.T. Bryson. 1994. 

Foliar washoff and runoff losses of lactoben, 

norflurazon and fluemeteron under simulated 

conditions. J.Agric. Food Chem. 42:2338-2343. 

287 Reeves. D.W. 1997. Personal communication. 

USDA-ARS.Auburn,Ala. 

277 Quesenbery, K.H. 1997. Personal communication. 

Univ. of Florida. Gainesville, Fla. 

BIBLIOGRAPHY 193

288 Reeves, D.W. and J.T.Touchton. Deep tillage 

ahead of cover crop planting reduces soil 

compaction for following crop. p. 4.Alabama 

Agricultural Experimental Station Newsletter. 

Auburn,Ala. 

289 Hoffman, Melinda A., Emilie E. Regnier and 

John Cardina. 1993.Weed and corn (Zea mays) 

responses to a hairy vetch (Vicia villosa) cover 

crop. Weed Tech. 7:594-599. 

290 Reynolds, M.O. et al. 1994. Intercropping 

wheat and barley with N-fixing legume species: 

A method for improving ground cover, N-use 

efficiency and productivity in low-input systems. 

J.Agric. Sci. 23:175-183. 

291 Rice, E.L. 1974. Allelopathy.Academic Press, 

Inc. N.Y. 

292 Roach,T. 1997. Personal communication. 

Dekalb. Dekalb, Iowa. 

293 Robertson,T. et al. 1991. Long-run impacts of 

cover crops on yield, farm income, and nitrogen 

recycling. pp. 117-120. In Cover Crops for Clean 

Water (W.L. Hargrove, ed.). Proc. Int’l Conf.April 

9-11, 1991.West Tennessee Experiment Station, 

Jackson,Tenn. Soil and Water Conservation 

Society.Ankeny, Iowa. 

294 Robinson, R.G. 1980. The Buckwheat Crop 

in Minnesota. Station Bulletin 539.Agricultural 

Experiment Station, Univ. of Minnesota, St. Paul, 

Minn. 

295 Rodale Institute. 1992. Managing Cover 

Crops Profitably. USDA/Sustainable Agriculture 

Network,Washington, D.C. 

296 Rothrock, Craig S. 1995. Utilization of winter 

legume cover crops for pest and fertility management 

in cotton. p. 11. Southern SARE 1995 


297 Roylance, Howard B. and K.H.W. Klages. 

1959. Winter Wheat Production. Bulletin 314. 

College of Agriculture, Univ. of Idaho, Moscow, 

Idaho. 

298 Ruberson, John R. 1997. Personal communication. 

Univ. of Georgia,Tifton, Ga. 

299 VOID 

300 Sustainable Agriculture Network. 1992. 

Managing Cover Crops Profitably. Rodale 

Institute staff (eds.).Washington, D.C. 

301 Sarrantonio, M. 1991. Methodologies for 

screening soil-improving legumes. Rodale 

Institute. Kutztown, Pa. 

302 Sarrantonio, Marianne. 1994. Northeast 

Cover Crop Handbook. Soil Health Series. 

Rodale Institute, Kutztown, Pa. 

303 Sarrantonio, M. and T.W. Scott. 1988.Tillage 

effects on availability of nitrogen to corn 

following a winter green manure crop. 

Soil Sci. Soc.Am. J. 52:1661-1668. 

304 Schonbeck, Mark and Ralph DeGregorio. 

1990. Cover crops at a glance. The Natural 

Farmer, Fall-Winter 1990. 

305 Scott, J.E. and L.A.Weston. 1991. Cole crop 

(Brassica oleracea) tolerance to Clomazone. 

Weed Sci. 40:7-11. 

306 Sexauer Company,The. 1995. Seed Bulletin. 

100 Main Ave. Brookings, S.D. 

307 Shipley, P.R., et al.1992. Conserving residual 

corn fertilizer nitrogen with winter cover crops. 

Agron. J. 84:869-876. 

308 Sheaffer, Craig. 1996.Annual medics: new 

legumes for sustainable farming systems in the 

Midwest. Project Report #LNC93-58. North 

Central Region SARE. Lincoln, Neb. 


309 Shrestha,A. et al. 1996.“Annual Medics.” In 

Cover Crops: MSU/KBS (factsheet packet). 

Michigan State Univ. Extension. East Lansing, 

Mich. 

310 Sideman, Eric. 1991. Hairy vetch for fall 

cover and nitrogen:A report on trials by MOFGA 

in Maine. Maine Organic Farmer & Gardener 

18:43-44. 

311 Sims, James R. 1980. In Timeless Seeds. 

“Seeding George black medic,”“George Black 

medic in rotation,”“George black medic as a 

green manure.” Conrad, Mont. 

312 Sims, James R. 1982. Progress Report. 

Montana Ag. Extension Service. Research Project 

#382. Bozeman, Mont. 

313 Sims, James R. 1988. Research on dryland 

legume-cereal rotations in Montana. Montana 

State Univ. Bozeman, Mont. 

314 Sims, James R. et al. 1991.Yield and bloat hazard 

of berseem clover and other forage legumes 

in Montana. Montana AgResearch 8:4-10. 

315 Sims, James R. 1995. Low input legume/- 

cereal rotations for the northern Great Plains- 

Intermountain Region dryland and irrigated 

systems. Project Report #LW89-14.Western 


316 Sims, Jim. 1996. Beyond Summer Fallow. 

Prairie Salinity Network Workshop, June 6, 1996, 

Conrad, Mont. Available from Montana Salinity 

Control Association, Conrad, Mont. 59425. 

317 Singogo,W.,W.J. Lamont Jr. and C.W. Marr. 

1996. Fall-planted cover crops support good 

yields of muskmelons. HortSci. 31:62-64. 

318 Smith, G.R. 1997. Personal communication. 

Texas A&M Univ. Overton,Texas. 

319 Smith and Sharpley. Sorghum and sudangrass. 

Univ. of Calif. SAREP Cover Crops Resource 

Page. http://www.sarep.ucdavis.edu/ccrop/ 

320 Smith, Michael W.1997. Personal communication. 

Oklahoma State Univ., Stillwater Okla. 

321 Snider, Joe et al. 1994. Cover crop potential 

of white clover: Morphological characteristics 

and persistence of thirty-six varieties. Mississippi 

Agricultural and Forestry Experiment Service 

Research Report 19:1-4. 

322 Stark, Jeffrey C. 1995. Development of 

sustainable potato production systems for the 

Pacific NW. Project report #LW91-29.Western 


323 Stiraker, R.J. et al. 1995. No-tillage vegetable 

production using cover crops and alley cropping. 

pp.466-474. In Soil Management in 

Sustainable Agriculture. Proc.Third Int’l Conf. 

on Sustainable Agriculture. 31 August to 4 

September 1993.Wye College, University of 

London, UK. 

324 Stivers, L.J. and C. Shennan. 1991. Meeting the 

nitrogen needs for processing tomatoes through 

winter cover cropping. J. Prod Ag. 4:330-335. 

325 Stoskopf. Barley. Univ. of Calif. SAREP 

Cover Crops Resource Page. http://www.sarep. 

ucdavis.edu/ccrop/ 

326 Stute, James K. 1997. Personal communication. 

Michael Fields Agricultural Institute. East 

Troy,Wis. 

327 Stute, Jim. 1996. Legume Cover Crops in 

Wisconsin.Wisconsin Department of Agriculture, 

Sustainable Agriculture Program. Madison, 

Wis. 27 pp. 

328 Stute, J.K. and J.L. Posner. 1995a. Legume 

cover crops as a nitrogen source for corn in an 

oat-corn rotation. J. Prod.Agric. 8:385-390. 

329 Stute, J.K. and J.L. Posner. 1995b. Synchrony 

between legume nitrogen release and corn 

demand in the upper Midwest. 

Agron. J. 87:1063-1069. 

BIBLIOGRAPHY 195

330 Stute, J.K. and J.L. Posner. 1993. Legume 

cover crop options for grain rotations in 

Wisconsin. Agron. J. 85:1128-1132. 

331 Sumner, D.R., B. Doupik Jr. and M.G. Boosalis. 

1981. Effects of reduced tillage and multiple 

cropping on plant diseases. Ann. Rev. 

Phytopathol. 19:167-187. 

332 Sumner, D.R. et al. 1983. Root diseases of 

cucumber in irrigated, multiple-cropping systems 

with pest management. Plant Dis. 67:1071-1075. 

333 Sumner, D.R. et al. 1986. Interactions of 

tillage and soil fertility with root diseases in snap 

bean and lima bean in irrigated multiple-cropping 

systems. Plant Dis. 70:730-735. 

334 Sumner, D.R. et al. 1986. Conservation tillage 

and vegetable diseases. Plant Dis. 70:906-911. 

335 Sumner, D.R., S.R. Ghate and S.C. Phatak. 

1988. Seedling diseases of vegetables in conservation 

tillage with soil fungicides and fluid 

drilling. Plant Dis. 72:317-320. 

336 Sumner, D.R. et al. 1991. Soilborne pathogens 

in vegetables with winter cover crops and 

conservation tillage. Amer. Phytopathol. Soc. 

Abstracts. 

337 Sustainable Farming Connection website. 

http://www.ibiblio.org/farming-connection/ 

338 Teasdale, John R. 1997. Personal communication. 

USDA-ARS. Beltsville, Md. 

339 Teasdale, John R. et al.1991. Response of 

weeds to tillage and cover crop residue. Weed 

Sci. 39:195-199. 

340 Teasdale, John R. and C.L. Mohler. 1993. Light 

transmittance, soil temperature and soil moisture 

under residue of hairy vetch and rye. Agron. J. 

85:673-680. 

341 Teasdale, John R. 1996. Contribution of cover 

crops to weed management in sustainable agriculture 

systems. J. Prod.Ag. 9:475-479. 

342 Temple, Steve. 1996.A comparison of conventional, 

low input or organic farming systems: 

Soil biology, soil chemistry, soil physics, energy 

utilization, economics and risk. Project Report 

#SW94-017.Western Region SARE. Logan, Utah. 

343 Temple, Steve. 1995.A comparison of conventional, 

low input and organic farming systems:The 

transition phase and long term 

viability. Project Report #LW89-18.Western 


344 Theunissen, J, C.J.H. Booij and A.P. Lotz. 1995. 

Effects of intercropping white cabbage with 

clovers on pest infestation and yield. Entomologia 

Experimentalis et Applicata 74:7-16. 

345 Thomas, Fred. 1997. Personal communication. 

CERUS Consulting. Richvale, Calif. 

346 Thompson, Dick. 1994. Personal 

communication. Boone, Iowa. 

347 Timeless Seeds. 1997. Untitled price sheet. 

Conrad, Mont. 

348 Townsend,Walt. 1994. No-tilling hairy vetch 

into crop stubble and CRP acres. Project Report 

#FNC93-28. North Central Region SARE. Lincoln, 

Neb. 

349 Tumlinson, J.H.,W.J. Lewis and L.E.M.Vet. 

1993. How parasitic wasps find their hosts. 

Sci.American 26:145-154. 

350 Univ. of California Cover Crops Working 

Group. March 1996. Cover Crop Research and 

Education Summaries. Davis, Calif. 50 pp. 

351 Univ. of California Sustainable Agriculture 

Research and Education Program (UCSAREP) 

Cover Crops Resource Page online at 



352 Varco, J.J., J.O. Sanford and J.E. Hairston. 1991. 

Yield and nitrogen content of legume cover 

crops grown in Mississippi. Research Report. 

Mississippi Agricultural and Forestry Experiment 

Station 16:10. 

353 Wagger, M.G. Personal communication. North 

Carolina State Univ. Raleigh, N.C. 

354 Wander, M.M. et al. 1994. Organic and 

conventional management effects on biologically 

active soil organic matter pools. Soil Sci. Soc. 

Am. J. 58:1120-1139. 

355 Weaver, D.B. et al. 1995. Comparison of 

crop rotation and fallow for management of 

Heterodera glycines and Meloidogyne spp. in 

soybean. J. Nematol. 27:585-591. 

356 Welty, Leon et al. 1991. Effect of harvest 

management and nurse crop on production 

of five small-seeded legumes. Montana Ag 

Research 8:11-14. 

357 Weitkamp. 1988, 1989. Medics, general. Univ. 



358 Weitkamp and Graves. Medics, general. Univ. 



359 Westcott, M.P. et al.1991. Harvest management 

effects on yield and quality of small-seeded 

legumes in western Montana. Montana 

AgResearch 8:18-21. 

360 Westcott, M.P. 1995. Managing alfalfa and 

berseem clover for forage and plowdown nitrogen 

in barley rotations. Agron. J. 87:1176-1181. 

361 Weston, Leslie A. 1997. Personal communication. 

Univ. of Kentucky. Lexington, Ky. 

362 Weston, Leslie A., Chandrashekhar I. Nimbal 

and Philippe Jeandet. 1998.Allelopathic potential 

of grain sorghum (Sorghum bicolor (L.) 

Moench) and related species. In Principles and 

Practices in Chemical Ecology. CRC Press, Boca 

Raton, Fla. 

363 Weston, Leslie A. 1996. Utilization of allelopathy 

for weed management in agroecosystems. 

Agron. J. 88:860-866. 

364 Wichman, David et al. 1991. Berseem clover 

seeding rates and row spacings for Montana. 

Montana AgResearch 8:15-17. 

365 Willard, C.J. 1927. An Experimental Study of 

Sweetclover. Ohio Agricultural Station Bulletin 

No. 405,Wooster, Ohio. 

366 William, Ray. 1996. Influence of cover crop 

and non-crop vegetation on symphlan density in 

vegetable production systems in the Pacific NW. 

Project Report #AW94-033.Western Region 

SARE. Logan, Utah. 

367 Williams et al. 1990. Ryegrass. Univ. of Calif. 



368 Williams,William A. et al. 1991.Waterefficient 

clover fixes soil nitrogen, provides 

winter forage crop. Calif.Ag. 45:30-32 

369 Wingard, Charles. 1996. Cover Crops in 

Integrated Vegetable Production Systems. Project 

Report #PG95-33. Southern Region 1996 


370 Wolfe, David. 1994. Management strategies 

for improved soil quality with emphasis on soil 

compaction. Research project #LNE94-44. 

Northeast Region SARE. Burlington,Vt. 

371 Wolfe, David. 1997. Soil Compaction: Crop 

Response and Remediation. Report No. 63. 

Cornell Univ., Department of Fruit and Vegetable 

Science, Ithaca, N.Y. 

BIBLIOGRAPHY 197

372 Wright, S.F. and A. Upadhaya. 1998.A survey 

of soils for aggregate stability and glomalin, a 

glycoprotein produced by hyphae of arbuscular 

mycorrhizal fungi. Plant Soil 198:97-107. 

374 Yoshida, H., H.Tsumuki, K. Kanehisa and 

L.J. Corcuera. 1993. Release of gramine from 

the surface of barley leaves. Phytochem. 

34:1011-1013. 

373 Yenish, J.P.,A. D.Worsham and A.C.York. 

1996. Cover crops for herbicide replacement in 

no-tillage corn (Zea mays). Weed Tech. 

10:815-821. 

APPENDIX H 

RESOURCES FROM THE 

SUSTAINABLE AGRICULTURE NETWORK 

SAN’s print and electronic products cover a range of 

topics, from tillage tool selection to interpreting a 

soil test for your conditions. Most publications 

can be viewed in their entirety at www.sare.org/ 

publications.(Prices are subject to change.) 

Books 

Building a Sustainable Business, 280 pp, $17 

A business planning guide for alternative and sustainable 

agriculture entrepreneurs that follows 

one farming family through the planning, implementation, 

and evaluation process. 

Building Soils for Better Crops, 240 pp, $19.95 

How ecological soil management can raise fertility 

and yields while reducing environmental 

impact. 

How to Direct Market Your Beef, 96 pp, $14.95 

How one couple used their family’s ranch to 

launch a profitable, grass-based beef operation 

focused on direct market sales. 

Manage Insects on Your Farm: A Guide to 

Ecological Strategies, 128 pp, $15.95 

Manage insect pests ecologically using crop diversification, 

biological control and sustainable soil 

management. 

The New American Farmer 2nd Edition, 

200 pp, $16.95 

Profiles 60 farmers and ranchers who are renewing 

profits, enhancing environmental stewardship 

and improving the lives of their families and communities 

with new approaches to agriculture. 

The New Farmers’ Market, 272 pp, $24.95 

Covers the latest tips and trends from leading sellers,managers,and 

market planners to best display 

and sell product. (Discount rates do not apply.) 

Steel in the Field, 128 pp; $18 

Farmer experience, agricultural engineering 

expertise and university research combine to 

tackle the hard questions of how to reduce weed 

management costs and herbicide use. 

How to Order Books 

Visit www.sare.org/WebStore,call (301) 374-9696 

or specify title and send check or money order to 

Sustainable Agriculture Publications, PO Box 753, 

Waldorf, MD 20604. 

Shipping & Handling: Add $5.95 for first 

book, plus $2 for each additional book shipped 

within the U.S.A.Call (301) 374-9696 for shipping 

rates on orders of 10 or more items, rush orders, 

or international shipments. Please allow 3-4 

weeks for delivery. MD residents add 5% sales tax. 


Bulk Discounts: Except as indicated above, 

25% discount applies to orders of 10-24 titles;50% 

discount for orders of 25 or more titles. 

Bulletins 

Diversifying Cropping Systems, 20 pp. 

Helps farmers design rotations, choose new 

crops, and manage them successfully. 

Exploring Sustainability in Agriculture, 16 pp. 

Defines sustainable agriculture by providing snapshots 

of different producers who apply sustainable 

principles on their farms and ranches. 

How to Conduct Research on Your Farm or 

Ranch, 12 pp. 

Outlines how to conduct research at the farm 

level,offering practical tips for both crop and livestock 

producers. 

Marketing Strategies for Farmers and 

Ranchers, 20 pp. 

Offers creative alternatives to marketing farm 

products, such as farmers markets, direct sales, 

and cooperatives. 

Meeting the Diverse Needs of Limited Resource 

Producers, 16 pp. 

A guide for agricultural educators who want to 

better connect with and improve the lives of 

farmers and ranchers who often are hard to 

reach. 

Profitable Pork: Strategies for Hog Producers, 

16 pp. (También disponible en español.) 

Alternative production and marketing strategies 

for hog producers,including pasture and dry litter 

systems, hoop structures, animal health and soil 

improvement. 

Profitable Poultry: Raising Birds on Pasture,16 pp. 

Farmer experiences plus the latest marketing 

ideas and research on raising chickens and 

turkeys sustainably, using pens, moveable fencing 

and pastures. 

SARE Highlights, 16 pp. 

(Available for 2003-2006) 

Features cutting-edge SARE research about profitable, 

environmentally sound farming systems 

that are good for communities. 

Smart Water Use on Your Farm or Ranch, 16 pp. 

Strategies for farmers, ranchers and agricultural 

educators who want to explore new approaches 

to conserve water. 

Transitioning to Organic Production, 20 pp. 

Lays out promising transition strategies, typical 

organic farming practices, and innovative marketing 

ideas. 

A Whole Farm Approach to Managing Pests,20 pp. 

Lays out ecological principles for managing pests 

in real farm situations. 

How to Order Bulletins 

Visit www.sare.org/WebStore,call (301) 504-5411 

or e-mail san_assoc@sare.org. 

Standard shipping for bulletins is free. Please 

allow 2-5 weeks for delivery. Rush orders that 

must be received within three weeks will be 

charged shipping fees at cost. Please call (301) 

504-5411 for more information on rush orders.All 

bulletins can be viewed in their entirety at 

www.sare.org/publications prior to placing your 

order. Bulletins are available in quantity for educators 

at no cost. 

Visit WWW.SARE.ORG 

Our website is your portal to grant opportunities 

available through the Sustainable Agriculture 

Research and Education (SARE) program,research 

results, a calendar of sustainable agriculture 

events and SAN publications and databases such 

as the on-line direct marketing resource 

guide. 

RESOURCES FROM SAN 199

READER RESPONSE FORM 

YOUR TURN: STRAIGHT TALK ABOUT THIS BOOK 

We want to know what you think about this book. 

Please take a few moments to complete the following 

evaluation. Your suggestions will help shape 

future SAN publications. 

About the book... 

1. How did you find out about Managing Cover 

Crops Profitably (Check all that apply). 

■ a flyer announcing the book 

■ the Internet or World Wide Web 

■ an extension agent or other consultant 

■ a farmer or rancher 

■ a farm publication (please specify) 

■ other (please specify) 

2. Which section(s) of the book most interested you: 

■ introductory chapters (please specify) 

■ charts 

■ individual cover crop sections 

■ appendices 

3. Did you find the information you needed 

■ almost all 

■ mostly 

■ somewhat 

■ very little 

If you answered somewhat or very little, please 

tell us what was missing. 

6. What topics would you like to see SAN cover in 

future books or bulletins 

About you... 

7. I am a (check your primary occupation): 

■ farmer/rancher 

■ state/federal agency employee 

■ university researcher 

■ student 

■ extension employee 

■ seed/equipment dealer 

■ crop consultant 

■ other _________________________________ 

8. I typically get my information about production 

practices from (check as many as apply): 

■ other farmers/ranchers 

■ books 

■ farm journals and newsletters 

■ extension or other agency personnel 

■ the Internet 

■ other 

9. I am from ___________________ (your state) 

10. I primarily grow (please specify crops/ 

livestock): 

4. Please rate each of the following 

(1 = poor, 5 = great) 

■ readability 

■ amount of information 

■ technical level of information 

■ drawings and charts 

■ resources for further information 

5. Are you doing anything differently as a result of 

reading this book If so, what 

Please return this form to: 

Sustainable Agriculture Publications 

#10 Hills Bldg. 




INDEX 

A 

Alfalfa, 10, 42, 84, 88, 94 

Alkaloids, 60–61, 161 

Allelopathy 

black oats, 159 

comparison of species, 

45–46, 52–53 

hairy vetch, 113 

oats, 62, 64 

rye,70 

sorghum-sudangrass hybrids, 

81 

subterranean clovers, 136 

sweetclovers, 144 

woollypod vetch, 152, 154 

Ammonia, 24 

Annuals. See also specific cover 

crops 

grasses, 54 

legumes, 85–86 

uses, 54 

Austrian winter peas. See Field 

peas 

Avena sativa. See Oats 

Avena strigosa. See Oats, black 

B 

Bacteria. See Disease management 

and sources; 

Microorganisms 

Barley, 58–61 

advantages and disadvantages, 

11, 52–53, 58–59 

crop systems, 41–42 

cultural traits, 50 

management, 59–61 

mixes of cover crops, 124, 

145 

performance and roles, 

48–49 

planting, 51, 59-61 

Barrel medic. See Medics 

Bees, 149 

Bell beans, 148, 159 

Beneficial insects. See Insect 

management and sources 

Biomass. See also Organic 

matter; Residue 

berseem clover, 88, 90 

crimson clover, 100–101 

field peas, 105–106 


legumes, 85 

medics, 126 

oats, 62 


81 



Birdsfoot trefoil, 131 

Blackeye peas. See Cowpeas 

Black medic. See Medics 

Black oats, 159 

Brassica campestris. See 

Rapeseed 

Brassica napus. See Canola 

Brassicas 

cash crops 

cover crop rotations for, 

15, 37 

sweetclover overseeding, 

146 

white clover, 150 

cover crops 

erosion prevention, 11 

for nematode management, 

32 

for pest reduction, 10 

Buckwheat, 54, 77–79 


52–53, 77–78 

comparative notes, 79 

cowpea mixtures, 98–99 

cropping systems, 37, 41, 42 




48–49 

for pest management, 31 

planting, 51,78 

Buffalo rolling stalk chopper, 

32–33 

Burclover. See Medics 

Bur medic. See Medics 

C 

Calcium, 19 

California. See West 

Canadian field peas. See Field 

peas 

Canola, 125 

Carbon to nitrogen ratio, 

22–23, 54 


grasses, 54 

hairy vetch, 113, 114 

legumes, 86 

Cereal grains. See Small grains; 

specific crops 

Cereal rye. See Rye 

Choppers/chopping, 32–33, 91, 

116, 129, 153–154. See also 

Forage clover. See also 

Sweetclovers; specific clover 

species. 

vs. medics, 125 

mixtures, 135 

for orchards, 14 

reseeding, 13 

for weed management, 33 

Clover, alsike clover, 131 

Clover, arrowleaf, 88 

Clover, balansa, 40, 158–159 

Clover, berseem, 87–94 


52–53, 87–88 


crop systems, 34, 36, 89, 

92–94 


inoculant, 92–93 


INDEX 201


48–49 

planting, 51, 88-90, 94 

Clover, crimson, 100–104 


52–53, 100–101 

comparative notes, 104, 122, 

158 

in crop rotations, 13, 35, 89, 

109–111 


grazing, 88 


mixtures, 112, 113, 118, 135 


48–49 

for pest management, 26–27, 

30 

planting, 51, 101-104 

residue, 91 

Clover, red, 127–131 


52–53, 127–128 


for corn>soybean systems, 

34, 36, 73 


fertilizer cost reduction, 9–10 



48–49 

planting, 51, 129, 131 

wheat nurse crop, 74 

Clover, rose, 135 

Clover, subterranean, 132–138 


52–53, 132, 133–134 





48–49 


planting, 51, 132-135, 138 

types and cultivars, 132–133 

Clover, white, 147–151 


52–53, 147–148 




for orchards, 14 

performance and roles, 13, 

48–49 

planting, 51, 148-149 

types, 147 

for vegetable production, 37 

Companion crops. See also 

Nurse crops 

annual ryegrass, 55–56 

berseem clover, 88, 91, 92–94 

cowpeas, 96 

crimson clover, 101 

oats, 63 

rye,67 

sweetclover, 142 


Conservation strips. See Strip 

cropping 

Corn Belt. See Midwest 

Corn cropping systems 

berseem clovers, 89, 92–93 

crimson clover, 89, 102 


field peas, 111 

hairy vetch, 112–113, 

115–116 

medic, 123–124 

planting time, 35 

red clover, 128, 129, 130, 131 

rotations, 34–36, 37–38, 41 

selecting cover crop, 14 


80 

subterranean clover, 133, 

137–138 


wheat, 72 

white clover, 148, 150 

woollypod vetch, 152 

Costs 

comparison of species, 44, 

49 

conventional vs. cover crop 

systems, 27 

corn crop systems, 130 


field pea seeds, 106 

inoculant, 92 

lupins, 160 

medics, 124 

oat crops, 62 

pesticides, 10, 27, 114 

red clover, 127–128, 131 

seed, 45, 51, 156 

sunn hemp, 161 



Cotton crop systems 

cowpeas, 96 

crop rotations, 39–40 


hairy vetch, 117–118 

pest management, 26–27, 

28, 29 

wheat, 74 

Cover crops. See also specific 

crops 

advantages and disadvantages 

for specific crops, 

45–46, 52–53 

benefits, 9–11 

crop rotations, 34–42 

cultural traits, 44–45, 50 


43–44, 48–49 

for pest management, 25–33 

planting recommendations, 

45, 51 

promising species, 158–162 

regional species, 43, 47 

selection criteria, 12–15 

for soil fertility and tilth 

development, 16–24 

testing on your farm, 

156–158 

Cowpeas, 95–99 


52–53, 95–96 


crop rotations, 72, 98–99 



mixtures, 82 



48–49 

planting and seeds, 51, 96-97, 

99 


Crop residue. See Residue 

Crop rotations. See also Crop 

systems 

berseem clover in, 92–94 

buckwheat in, 79 

corn-soybean systems, 34–36, 

72–73 

for cotton production, 

26–27, 39–40 

cowpeas in, 98–99 

crimson clover in, 102–103 

dryland cereal-legume systems, 

40–42 

fertilizer application, 10 

field peas in, 106, 108–109 

foxtail millet in, 160 

hairy vetch in, 112–113 

legumes in, 85 

medics in, 121, 123–124 

pesticide and herbicide 

reduction, 10 

planning, 12–15, 34 

red clover in, 128, 130 

rye in, 66 

sorghum-sudangrass hybrids 

in, 83–84 

sunn hemp in, 161 

for vegetable production, 

36–39 

winter wheat in, 72–73 

Crop systems. See also Crop 

rotations 

berseem clover, 92–94 

cowpeas, 98–99 



incorporating cover crops, 

13 


83–84 

subterranean clovers, 

137–138 

sweetclovers, 145–146 

white clover, 149–150 

Crotalaria juncea. See Sunn 

hemp 

Crowder peas. See Cowpeas 

Cultivation 

comparison of, 46, 52–53 

cowpeas, 98 

in disease management, 

29–30 



red clover, 129–130 

D 

Dairy farming, 14 

Damping off, 30 

Data collection for trials, 157 

Decomposition 

carbon to nitrogen ratio, 

22–23 

crimson clover, 103–104 

of grasses, 54 

microorganisms in, 17–18, 19 

Denitrification, 24 

Disease management and 

sources 

annual ryegrass, 57 

balansa clover, 158 

barley, 60, 61 

berseem clover, 91 


in corn-soybean system, 36 

cover crop benefits, 10, 27, 

29–32 

cowpeas, 96, 97–98 




lupins, 161 

medics, 125 

oats, 64 


rye, 57–71 


81–83, 85 

species comparison, 45–46, 

52–53 




vegetable production, 37 

wheat, 76 



Disking. See Tillage 

Drought. See also Soil moisture 




Dryland production 

cereal-legume crop rotations, 

40–42 

cover crops, 11 

field peas, 106, 107, 108–109 

medics, 120, 125 

sweetclovers, 139–146, 144, 

146 

Dry matter. See Residue 

Dutch white clover. See Clover, 

white 

E 

Economics. See Costs 

Egyptian clover. See Clover, 

berseem 

Eragrostis tef. See Teff 

Erosion prevention 


barley, 58 

cover crops, 10–11, 16 

medics, 121 

mixtures, 86–87 

performance and roles of 

species, 44, 48 

regional species comparison, 

47 

rye,66 


winter wheat, 72 

Establishment. See 

Seeding/seeds, specific cover 

crops 

Estrogen, 136 

INDEX 203

F 

Faba beans. See Bell beans 

Fagopyrum esculentum. 

See Buckwheat 

Fallow 

in dryland production, 40–42 

vs. grain legumes, 109 

vs. medics, 120 

selecting cover crops for, 

12–13 

sweetclover rotations, 142, 

144, 145 

Farmer accounts 

Alger–perennial medic for 

soil quality, fertility, 121 

Anderson–woollypod vetch 

reseeding, 153; as frost 

protectant and recognizing 

seedlings, 152 

Bartolucci–establishing 


Bennett–rye for weed management 

in soybeans, 67 

Burkett–winter peas for disease 

suppression, 108 

Carter–wheat production, 74 

de Wilde–killing rye, 69; rye 

for mulch, 70 

Erisman–timing rye kill, 69 

French–cowpeas in rotation, 

98 

French–field peas, 110 

Granzow–sweetclovers for 

grazing and green manure, 

142 

Groff–incorporating rye seed 

68; killing rye, 69 

Guenther–crimson-berseem 

clover with corn, 89 

Kirschenmann–sweetclover 

with nurse crops, 145 

LaRocca–barley in vineyard 

mix 

Matthews–white clover in 

contour strips, 149 

Mazour–managing sweetclover 

escapes, 146 

Moyer–no-till rye into 

standing vetch 

Nordell–early plowing to 

avoid slugs, 144; sweetclover-clover 

mixes, 146; 

weed management in vegetables, 

38–39 

Podoll–sweetclover weevil 

cycle, 144 

Farming organizations, 170–172 

Fava beans. See Bell beans 

Feed supplements, 65 

Fertilizer 

for fallow systems, 109 

red clover systems, 128, 130, 

131 

reducing, 9–10, 93 

for subterranean clover, 136 

Fescue, 81, 114, 115 

Field peas, 105–111 


52–53, 105–107 

cropping systems, 34, 41 


for fertilizer reduction, 10 

for grazing and nitrogen, 110 



48–49 

planting and seed, 51, 106- 

108, 111 

Flail choppers for sorghumsudangrass 

hybrids, 82, 83 

Flail mowers. See 

Mowers/mowing 

Flax, 42 

Forage 

berseem clover, 88, 90, 91 

cowpeas, 96 

field peas, 106, 110 


medics, 121, 126 

oats, 64–65 

red clover, 131 

rye,71 


81 


sweetclovers, 142, 146 



Foxtail millet, 160 

Freedom to Farm Act, 98 

Frost damage, 152 

Frostseeding, 129, 143, 148–149 

Fruits. See also Orchards; 

Vineyards 

rye for,66 


G 

German millet. See Foxtail 

millet 

Grain rye. See Rye 

Grains. See Small grains; specific 

crops 

Grasses 

carbon to nitrogen ratio,23,54 

for fertilizer reduction, 10 

for moisture conservation, 11 

for nematode management, 

32 

nitrate conservation, 18–19 

in soil health, 17, 18, 24 

subterranean clover 

mixtures, 134 

Grass waterways, 57 

Grazing 

annual ryegrass, 56, 57 



cowpeas, 96 


in dryland cereal-legume 

systems, 42 

field peas, 106, 110, 111 

grass cover crops, 54 


livestock poisoning, 81, 85, 

139–140, 142 

lupins, 161 

medics, 121 

oats, 64–65 



rye,71 



85 


134–135, 136 

sweetclovers, 139–140, 141, 

142, 144, 146 

wheat, 76 

Greenchopping berseem 

clover, 91 

Green fallow systems, 145 

Green manures 

berseem clover, 88, 89, 

90–91, 94 

cowpeas, 95 

field peas, 106, 109 

oats, 63 




Groundwater, 109 

H 

Habitats. See Insect management 

and sources 

Hay 


berseem clover/oats, 88 


cowpeas, 96 


medic/grass mixtures, 

124–125 

oats, 64–65 


Health and safety issues, 11 

Hemp, sunn, 161 

Herbicides 

for annual ryegrass, 57 

for berseem clover, 91 

buckwheat sensitivity to, 79 

in corn production, 26–27 

in cotton production, 40 

cover crops for reducing, 10 

for cowpeas, 97 

crimson clover and, 101, 103 

for foxtail millet, 160 

for hairy vetch, 116 

for medics, 121, 125 

for oilseed species, 145 

for red clover, 129–130 

for rye, 67, 70 

for sorghum-sudangrass 

hybrids, 82 

for subterranean clovers, 

135, 138 

for sweetclovers, 144 

for wheat and potatoes, 75 

for white clover, 150 

High chopping woollypod 

vetch, 153–154 

Hordeum vulgare. See Barley 

Hubam. See Sweetclovers 

Humus. See Organic matter 

I 

Inoculants, 45, 51, 92–93, 149, 

156, 158 

Insecticides, 26–27 

Insect management and 

sources 


barley, 61 

bell beans, 159 


buckwheat, 78, 79 

cotton, 40 

cover crops for reducing, 10, 

25–29, 30–31 

cowpeas, 95–96, 97, 104 




lupins, 161 

medics, 122 

oats, 64 


rye,70 


82, 83 


52–53 


sweetclovers, 141, 144–145 

wheat, 76 



Integrated Pest Management 

(IPM), 28–29, 95–96 

Interseeding 

barley, 60 

in corn-soybean system, 36, 

41 

cowpeas, 96 

in dryland cereal-legume 

crop rotations, 37 

legumes and cereal grains, 12 

medic, 89, 121 



subterranean clovers with 

wheat, 137 

sweetclover and corn, 145 

in vegetable crop rotations, 

37 

IPM. See Integrated Pest 

Management 

Irrigation 

barley, 60 

potatoes with wheat, 75 


for underseeding, 12 


Italian ryegrass. See Ryegrass, 

annual 

K 

Killing and controlling, 57 


barley, 60 


cowpeas, 97 




medics, 124 

oats, 64 


rye, 69–70 





INDEX 205

L 

Labor, 39 

Ladino clover. See Clover, white 

Lana vetch. See Vetch, 

woollypod 

Leaching, 11, 18–19. See also 

Nitrogen management and 

sources 

Legumes. See also specific 

crops 


carbon to nitrogen ratio, 23 

in crop rotations, 14, 37, 

40–42, 108–111 

erosion prevention, 10–11 

humus production, 17 

mixtures, 62–63, 72–73 

mycorrhizae, 19 

nitrogen fixation and release, 

9, 20–21, 92–93, 130, 148 


33 

Lentils, 41 

Ley cropping subterranean 

clovers, 136 

Ley system, medics for, 122, 124 

Livestock poisoning, 81, 85, 

139–140, 142 

Living mulches 

for soil improvement, 13 


white clover, 148, 149–150 

Lolium multiflorum. See 

Ryegrass, annual 

Lotus corniculatus. See 

Birdsfoot trefoil 

Lupins, 160–161 

Lupinus albus. See Lupins 

Lupinus angustifolius. See 

Lupins 

M 

Malting barley, 10 

Mammoth clover. See Clover, 

red 

Management. See specific 

aspects of management 

Medics, 119–126 


52–53, 119–123 

comparative notes, 125, 138 

crop systems, 41, 89 




48–49, 121 

planting and seeding, 51, 

122-123, 125–126 

Medigo spp. See Medics 

Medium red clover. See Clover, 

red 

Melilotus alba. See 

Sweetclovers 

Melilotus officinalis. See 

Sweetclovers 


humus production, 17–18, 19 

nitrogen fixation, 20–21 

plant surface, 29–30 

rhizobium bacteria, 92–93 

Mid-Atlantic 


field pea crop systems, 108, 

111 

hairy vetch, 112–113, 115, 

116, 118 

rye, 66–71 

subterranean clovers, 133, 

137–138 


top species for, 47 

vegetable production, 37, 

38–39 

weed management, 33 


Midwest 

berseem clover, 89–90, 91, 

92–94 

buckwheat, 79 


cowpeas, 98 



hairy vetch crop systems, 

113, 115 

medics, 120, 123–125 

oats, 63 

red clover, 129–130, 130 

rye, 66, 69, 70 




Millets, 131, 160 

Mixtures/mixed seeding. See 

also Companion crops; 

Nurse crops 


barley, 59–60 



carbon to nitrogen ratio, 23 




hairy vetch, 112, 113–114, 

118 

medic, 124–125 


rye, 67, 68, 69 


82 

wheat, 74 

Mow and blow system, 94 

Mowers/mowing 

berseem clover, 90–91, 94 

buckwheat, 78 

cowpeas, 97 

fescue, 114 

flail 

for berseem clover, 91 

for cowpeas, 97 



insect management, 29 

medics, 121 

red clover, 129–130, 131 

rye,69 

sicklebar 

cowpeas, 96 


sorghum-sudangrass 

hybrids, 82, 83 


80–81, 82 



137 

sweetclovers, 143, 144, 146 

white clover, 149–150 

woollypod vetch, 153–154 

Mucuna deeringiana. See 

Velvetbeans 

Mulches. See also Living 

mulches 


rye, 70–71 


82 


for weed management, 

32–33 


Mycorrhizae, 19, 140 

N 

Nematodes 



barley, 60, 61 



cowpeas, 96, 97–98 



management using cover 

crops, 10, 27, 30–32 

oats, 64 


81, 85 


52–53 




New Zealand white clover. 

See Clover, white 


sources 




calculating amount in cover 

crop, 22–23 

cover crop effect on 

conservation and leaching, 

11, 18–19 

legume fixation and 

release, 20–21 

organic matter, 17 

potential losses, 23–24 

regional species 

comparison, 47 

species comparison, 43, 48 

in specific crops, 14–15 

tillage systems, 21–23 

cowpeas, 95, 98 

crimson clover, 100, 101, 

102, 103 

in crop rotations 

corn-soybean system, 36 

dryland cereal-legume 

systems, 42 


39 

field peas, 106, 109–111 

grasses, 54 

hairy vetch, 112–113, 115, 

116 

legumes, 85–86 

lupins, 161 

medics, 120, 121, 124 

mixtures, 86 

oats, 62 

plant counts for estimation, 

130 

red clover, 127, 129, 130, 131 

rye, 66, 67, 69 

sorghum-sudangrass hybrid 

management, 83–84, 85 


136, 137, 138 

sweetclovers, 140, 143–144, 

146 

wheat, 73 

white clover, 147–148, 148, 

150 


woollypod vetch, 151–152, 

152 

Nonlegumes. See also specific 

crops 


management, 54 

nitrogen, 18–19, 54 

uses, 54 

Northeast 

buckwheat, 79 


field pea crop systems, 108 


oats, 63 

rye,66 


80–81, 82, 83–84 



Northern Plains 




107, 108–109 

medics, 119–122 


sweetclovers, 143, 144, 145, 

146 

Northwest. See Pacific 

Northwest 

No-till systems. See also Tillage 

corn 

with hairy vetch, 9, 

112–113 


with subterranean clover, 

133 

cotton production, 40, 

117–118 

cowpeas, 97 


erosion prevention, 10–11 

hairy vetch, 114, 115–116, 

117–118 

for insect management, 

27–28 

nitrogen conservation, 18–24 


81, 82 


sweetclovers in grain 

stubble, 143 

INDEX 207

vegetables, 15 

wheat, 74 

Nurse crops 


barley, 58–59 


buckwheat, 78 

medics, 123, 125 

mixtures, 87 

oats, 62–63 

rapeseed for sweetclover, 

145 

wheat, 74 

Nutrients. See Nitrogen; 

Phosphorus 

O 

Oats, 62–65 


52–53, 62–63 

comparative notes, 61, 65 

crop systems, 36, 37, 113, 

160 


fertilizer reduction, 9 


mixtures, 88, 89, 92–94, 143 


48–49 


Oats, black, 159 

Orchards 


cowpeas, 96 

insect management, 28–29 

medics, 120 

mixtures for, 86 



133, 136, 137 


Organic matter 

barley, 58 

buckwheat, 77, 79 

components, 17 

medics, 120–121 

microorganisms and aggregation, 

17–18, 19 

rye,66 


84 

wheat, 73 


Overseeding. See Underseeding 

P 

Pacific Northwest 


83 

species for, 47 


wheat with potatoes, 75 

Pasture. See also Grazing 



81 

Peanuts, 26–27, 29 

Pearl millet, 160 

Peas. See Cowpeas; Field peas 

Perennials. See also specific 

crops 

grasses, 54 

legumes, 85 

nitrogen fixation, 92 

Pest management. See Disease 

management and sources; 

Insect management and 

sources;Weed management and 

sources 

Phosphorus 

buckwheat, 77–78, 79 

conservation by cover crops, 

19 



red clover leaching, 131 



Pisum sativum subsp. arvense. 

See Field peas 

Plant counts for nitrogen estimation, 

130 

Planting. See Establishment; 

Seeding/seeds 

Plastic mulches, 118 

Potassium, 19, 66, 72 

Potatoes, 10, 30, 37, 75, 83–84 

Press-wheel drill, 141 

Profitability. See Costs 

R 

Rainfall. See Drought; Soil 

moisture 

Rapeseed, 85, 145 

Reseeding 


barley, 60 


clovers, 13 

comparison of species, 45, 

51 

in cotton crop rotations, 40 


medics, 121–122, 126 

mixtures, 86 


135–136, 137–138 



Residue 


buckwheat, 77 



cowpeas, 98 



grasses, 54 




82, 83, 85 

species comparison, 43, 48 

Rhizobium bacteria, 92–93 

Rice, 137 

Rice straw, 59 

Rollers for berseem clover, 91 

Rolling stalk chopper, 32–33, 

116, 129 

Rotations. See Crop rotations 

Runoff reduction, 101 

Rye, 65–71 


52–53, 65–67 



crop systems, 34–36, 39, 40, 

41, 160 


hairy vetch mixtures, 114, 

115, 118 


nitrate conservation, 11, 

18–19 


48–49 


30, 32, 70–71 

planting and seed, 51, 67-68, 

71 

Ryegrass, annual, 55–57 


52–53, 55–56 



vs. perennial, 57 


48–49 



Ryegrass, perennial, 13, 57 

S 

Safflower, 37–39 

Secale cereale. See Rye 

Seeding/seeds. See also 

Interseeding; Reseeding; 

specific cover crops 

Underseeding 




comparison of species, 51 

in corn>soybean system, 35 

foxtail millet, 160 

grasses, 54 

lupins, 160 


teff, 161–162 

testing on your farm, 

156–157 

Seed suppliers, 166–170 

Sesbania mixtures, 82 

Setaria italica. See Foxtail 

millet 

Shading, 150 

Small grains. See also specific 

crops 

berseem clover as companion 

crop, 91 

for corn-soybean systems, 

35–36, 41 

erosion prevention, 11 

fertilizer reduction, 10 

field pea mixtures, 105, 

107–108 


interseeding, 12 

medics in rotation, 124 

overseeding with berseem 

clover, 90 

red clover plantings, 129 

selecting cover crop for, 13, 

14 

Small-seeded horse beans. See 

Bell beans 

Snail medic. See Medics 

Soil erosion. See Erosion 

prevention 

Soil fertility and tilth. See also 


sources 


barley, 58 

buckwheat, 78–79 

cover crops for improving, 

10, 16–24 

crop rotations for, 13 

dryland cereal-legume 

systems, 42 



regional species comparison, 

47 

rye,71 


81, 84 

species comparison, 43, 48, 

52–53 




wheat, 73, 74 



Soil moisture. See also Drought; 

Dryland production 

barley, 60 

in corn-soybean systems, 35 

cover crops for conserving, 

11 


field peas, 106, 109, 111 



legumes, 145 

medics, 125 

mixtures, 86 

in nitrogen fixation, 21 

potatoes with wheat, 75 

rye killing and, 69 


132–133, 136, 137 



Soil organisms, 24. See also 


Soil temperature, 21, 130 

Sorghum, 133, 136 

Sorghum-sudangrass hybrids, 

80–85 


52–53, 80–81, 84 

comparative notes, 80, 84–85 





48–49 

planting and seed, 51, 82, 85 

for vegetable production, 37, 

38 

Sorgoleone, 81 

South 


crimson clover, 101, 102, 103 


109–111, 111 

INDEX 209

hairy vetch crop systems, 

112, 115, 117–118, 122 

rye, 66, 69 


136, 137 


weed management, 33 

Southern peas. See Cowpeas 

Southern spotted bur medic. 

See Medics 

Soybeans 

berseem clover for, 92–93 

cotton intercropping, 96 

crop rotations, 34–36, 41 

field pea overseeding, 111 

hairy vetch overseeding, 114 

medics in, 124 

nematode management, 32 

red clover for, 129, 130 

rye for, 66, 67 

wheat for, 72, 74, 75 

Spring oats. See Oats 

Spring peas. See Field peas 

Straw, 59 

Strip cropping 




cowpeas, 97 

rye,66 


Subclover. See Clover, 

subterranean 

Subsoil looseners, 47, 52–53, 

80–81 

Sudangrass, 83. See also 

Sorghum–sudangrass hybrids 

Sudax. See Sorghum-sudangrass 

hybrids 

Sudex. See Sorghum-sudangrass 

hybrids 

Sugarbeets, 10, 32, 59, 60 

Sunflowers, 145 

Sunn hemp, 161 

Sustainable Agriculture 

Network, 198–199 

Sweetclovers, 139–146 


52–53, 139, 140–141 


in crop rotation, 72 



performance and roles, 13, 

48–49 

planting and seed, 51, 

141-143, 145-146 

types, 139–140 

for vegetable production, 37, 

38–39 

wheat nurse crop, 74 

T 

Teff, 161–162 

Tillage. See also No-till systems 

conservation tillage 

for disease management, 

30–31 


26–27 

conventional till 

corn and subterranean 

clover, 133 

nitrogen conservation, 

18–24 

organic matter accumulation, 

18 

cotton and peanuts, 26–27 


oats, 64 

reduced tillage for rye, 71 

ridge-till for medics in corn, 

124 

rotary tillage for white 

clover, 150 


82, 83 

strip-till 

corn and peanuts, 26–27 



27–28 

rye,70 


sweetclovers, 142, 145–146 


Trials on your farm, 156–158 

Trifolium alexandrinum. See 

Clover, berseem 

Trifolium balansae. See Clover, 

balansa 

Trifolium brachycalcycinum. 

See Clover, subterranean 

Trifolium incarnatum. See 

Clover, crimson 

Trifolium pratense. See Clover, 

red 

Trifolium repens. See Clover, 

white 

Trifolium subterraneum. See 

Clover, subterranean 

Trifolium yanninicum. See 

Clover, subterranean 

Triticum aestivum. See Wheat, 

winter 

U 

Undercutters, 32–33, 116, 135 

Underseeding 





in crop rotation, 12–13 



medics, 123–124, 124–125, 

126 

oats, 63 

red clover, 128, 129 

rye,66 

sweetclovers, 142, 145, 146 


wheat, 73 


Universal Soil Loss Equation, 16 

V 

Vegetables 

annual ryegrass for, 55–57 

berseem clover for, 91, 94 


cowpeas for, 98 


crimson clover for, 102, 103 

crop rotations, 13, 36–39 

disease management, 30 

foxtail millet for, 160 

hairy vetch for, 116, 117, 118 

insect management, 27–29 

medics for, 125 

rye for, 66, 68, 70–71 



81, 83 

subterranean clovers for, 133, 

134, 136, 137–138 

sweetclover overseeding, 146 

white clover for, 148, 

149–150 

woollypod vetch for, 152 

Velvetbeans, 99 

Vetch, 87, 159 

Vetch, bigflower, 70 

Vetch, cahaba white, 31 

Vetch, common, 37–39, 

109–111, 155 

Vetch, hairy, 112–119 


52–53, 112–114 


for corn-soybean systems, 

34–36, 41, 72 

crop systems, 117–119 


fertilizer reduction, 9–10 



48–49 

for pesticide reduction, 10 

planting and seed, 51, 

114-119 

residue, 91 

rye mixtures, 68 

in small grain production, 14, 

109–111 

strip cropping with wheat, 

94 


Vetch, purple, 37–39, 155 

Vetch, woollypod, 119, 151–155 


52–53, 151–152 





48–49 

planting, 51, 151-155 

for vegetable production, 

37–39 

Vicia dasycarpa. See Vetch, 

woollypod 

Vicia faba. See Bell beans 

Vicia villosa. See Vetch, hairy 

Vicia villosa ssp. dasycarpa. See 

Vetch, woollypod 

Video resources, 165 

Vigna unguiculata. See 

Cowpeas 

Vineyards 

annual ryegrass for, 55–57 

barley for, 59–60, 61 

buckwheat for, 79 

cowpeas for, 96 

medics for, 120 


84 

woollypod vetch for, 151, 

153–154 

Virus. See Disease management 

and sources 

W 

Water quality, 11 

Weed management and sources 

annual ryegrass, 55, 57 

barley, 58, 60–61 



buckwheat, 77 

cotton production, 40 

cover crops 

management using, 27, 

32–33 



species comparison, 47, 

52–53 




medics, 120, 124 

oats, 62, 63, 64 

rye, 66–67, 70 


81, 82, 84, 85 


137–138 


teff, 162 


38–39 

wheat, 73, 74–75 



West 

barley, 58 


buckwheat, 79 


field pea crop systems, 

107–108 


medics, 120, 123–124, 126 


133–138 


vegetable crop systems, 

37–39 


Wheat, winter, 72–76 


52–53, 72–73 

berseem clover as 

companion, 94 

crop rotations, 36, 41–42, 

160 



medic plantings and, 120, 

121, 124–125 


48–49 

INDEX 211


planting and seed, 51 

red clover plantings, 129, 130 

subterranean clover 

interseeding, 137 

sweetclover rotations, 140, 

142, 144 


White sweetclover. See 

Sweetclovers 

Winter rye. See Rye 

Y 

Yellow mustard, 84 

Yellow sweetclover. 

See Sweetclovers 

Yields 

corn, 93 

cover crops in increasing, 10 

rye effect on, 67, 69

Managing Cover Crops Profitably - Valley Crops Home

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?