Managing Cover Crops Profitably: 2Nd Edition

SUSTAINABLE AGRICULTURE NETWORK THE NATIONAL OUTREACH ARM OF USDA-SARE HANDBOOK SERIES BOOK 3

Managing Cover Crops Profitably SECOND EDITION

A publication of the Sustainable Agriculture Network with funding by the Sustainable Agriculture Research and Education Program of CSREES, U.S. Department of Agriculture

Sustainable Agriculture Network National Agricultural Library Beltsville, MD 20705-2351 Copyright © 1998 by the Sustainable Agriculture Network, Library of Congress Cataloguing-in-Publication Data with funding from the Sustainable Agriculture Research and Education (SARE) program of the Cooperative State Research Managing cover crops profitably.—2nd ed. Education and Extension Service (CSREES),U.S.Department of p. cm.–(Sustainable Agriculture Network handbook series Agriculture. Reprinted in 2000. bk. 3) Includes bibliographical references (p. ) and index. SAN, the national outreach partner of the USDA SARE pro- ISBN 1-888626-04-6 (pbk) gram, is a consortium of individuals, universities and govern- 1. Cover crops—United States—Handbooks, manuals, etc. ment, business and nonprofit organizations dedicated to the I. Sustainable Agriculture Network. II. Series. exchange of information on sustainable agricultural systems. SB284.3.U6M36 1998 631.5’82—dc2l 98-9887 For more information about the Sustainable Agriculture CIP Network, or about other SAN publications, contact: 2 4 6 8 9 7 5 3 1 Andy Clark SAN Coordinator Printed in the United States of America on recycled paper. c/o AFSIC, Room 304 National Agricultural Library The U.S. Department of Agriculture (USDA) prohibits discrim- 10301 Baltimore Avenue ination in all its programs and activities on the basis of race, Beltsville, MD 20705-2351 color, national origin, gender, religion, age, disability, political PH: 301-504-6425 beliefs, sexual orientation, and marital or family status. (Not all FAX: 301-504-6409 prohibited bases apply to all programs). Persons with disabili- [email protected] ties who require alternative means for communication of www.sare.org program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at 202-720-2600 (voice SARE is a competitive grants program. It provides funding for and TDD). research and education projects that promote agricultural systems that are profitable, environmentally sound and To file a complaint of discrimination, write USDA, Director, enhance the viability of rural communities nationwide. Office of Civil Rights, Room 326-W,Whitten Building, 14th and Independence Avenue, SW,Washington,DC 20250-9410 or call For more information about the SARE program and SARE (202) 720-5964 (voice or TDD).USDA is an equal opportunity grants, contact: provider and employer. Office of Sustainable Agriculture Programs U.S. Department of Agriculture Every effort has been made to make this book as complete and 1400 Independence Ave., S.W.,Stop 2223 as accurate as possible and to educate the reader.This text is Washington, D.C. 20250-2223 only a guide,however,and should be used in conjunction with other information sources on crop, weed and farm manage- Material for this book and its covers was researched written, ment. No single cover crop strategy will be appropriate and illustrated,edited and produced for the Sustainable Agriculture effective for all conditions. The editor/authors and publisher Network.The book concept, format, and selection of featured disclaim any liability,loss,or risk,personal or otherwise,which farmers and content reviewers were developed under the is incurred as a consequence, directly or indirectly, of the use auspices of the Sustainable Agriculture Network. and application of any of the contents of this book. To order copies of this book, send a check or purchase order Mention, visual representation or inferred reference of a prod- for $19 plus $3.95 shipping and handling to: uct, service, manufacturer or organization in this publication Sustainable Agriculture Publications does not imply endorsement by the USDA, the SARE program Hills Building, Room 10 or the authors.Exclusion does not imply a negative evaluation. University of Vermont Burlington,VT 05405-0082 Graphic design, interior layout and cover design: Diane Buric. Interior illustrations by: 1. Marianne Sarrantonio (reprinted Call 802-656-0484 to order by credit card. For first book sent with permission from the Northeast Cover Crop Handbook. outside of N. America, please add $6. Add $2.50 for each 1994. Rodale Institute. Emmaus, PA); and 2. Elayne Sears. additional book. Please include your mailing address and Copy Editing:Valerie Berton and Andy Clark. Indexing: Nancy telephone number. Hopkins. Printing: Jarboe Printing, Washington, D.C.. Cover photos by Tom Gettings;orchard photo by Chuck Ingels, Univ. The Sustainable Agriculture Network Handbook Series previ- of Calif. Extension. ous titles include Book 1: Managing Cover Crops Profitably (1st Edition), edited by the staff of the Rodale Institute; and This book was written by Greg Bowman, Christopher Book 2: Steel in the Field: A Farmer’s Guide to Weed Shirley and Craig Cramer, of CMR Editorial Services, for Management Tools,1997, edited by Greg Bowman. the Sustainable Agriculture Network. ACKNOWLEDGMENTS

his book represents a true cooperative and Jim Stute, Michael Fields Agricultural Institute, effort. Most writing and research was by East Troy, Wis.; Richard Dick, Oregon State TChristopher Shirley, Greg Bowman and University; Jim Sims, Emeritus Professor, Montana Craig Cramer, formerly writers/editors for the State University; Chuck Ingels, University New Farm Magazine. Their experience writing of California Extension Service. Andy Clark, for the agricultural community shows in their Coordinator of the Sustainable Agriculture ability to incorporate a vast amount of research Network, oversaw the project and coordinated data and farmer experiences into this publication. the efforts of the writers, the designer and the Contributors Marianne Sarrantonio, University of editorial board. Maine, Orono, ME, Sharad Phatak, University of The complete manuscript was reviewed at least Georgia, and Andy Clark, Coordinator of the twice by each member of the editorial board. It was Sustainable Agriculture Network (SAN) each also reviewed by Mark Davis, Delaware State wrote sections of the book. Robert Myers, University;John Luna,Oregon State University; Wayne Reeves, Seth Dabney and Steve Diver, Appropriate Technology Chuck Ingels contributed to Transfer for Rural Areas (ATTRA), Appendix B, Up-and-Coming Fayetteville, Ark.; John and Cover Crops. Lorraine Merrill, Stuart Farm, Farmers played a major Stratham,N.H.;John Teasdale, role in developing the USDA-ARS, Beltsville, Md.; book, detailing their Phil Bauer, USDA-ARS, cropping systems and Florence, S.C.; Morris the management of Decker,Professor Emeritus, cover crops on their University of Maryland; farms. Some were con- Noah Ranells, North tacted repeatedly for Carolina State University; further clarification, and and Valerie Berton, SARE many also reviewed sec- communications specialist. tions of the manuscript. Individual chapters of The value of the contribu- Managing Cover Crops tions by farmers using cover Profitably, 2nd Edition were crops in the field cannot be under- reviewed by cover crop experts estimated. They generously gave of from the farm and research their time to provide true ground-testing and communities.These farmers and scientists are reality-checking to strenthen this publication. too numerous to mention here, but their contri- A volunteer editorial board consisted of faculty butions were invaluable to this effort. and researchers from around the country: Rob In preparation for the second edition, the first Myers, Jefferson Institute,Columbia, Mo., formerly edition was critically reviewed by Morris Decker, director of SARE; Fred Magdoff, Northeast Region Professor Emeritus, University of Maryland; Zane SARE, University of Vermont; Seth Dabney, USDA- Helsel, Rutgers University; and Andy Clark, SAN. ARS Soil Sedimentation Lab;Wayne Reeves, USDA- Fred Magdoff, who was the driving force behind ARS National Soil Dynamics Lab; Marianne the first edition, participated in planning and Sarrantonio, University of Maine; Walter Goldstein 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 support of the Sustainable Agriculture Network Brusko at Rodale Institute, was used liberally in (SAN). SAN is the communications and outreach the development and writing of this second arm of the SARE program. Other SARE support edition. came in the form of extensive planning, design, Mary Gold and Abiola Adeyemi, from the writing and editing by SARE communications Alternative Farming Systems Information Center specialist Valerie Berton, College Park, Md. SAN at the National Agricultural Library,provided com- publications committee chair Beth Holtzman, prehensive literature searching and facilitated the Burlington,Vt., contributed publication oversight, duplication and lending of cover crop literature contract management and overall good sense to the writers. Abiola Adeyemi also compiled about publishing sustainable agriculture infor- parts of the Appendices and provid- mation. Other members of the SAN ed clerical support,particularly dur- Management Committee commented on ing the reviews of the book. early plans for the book, helped develop Consulted repeatedly for budgets, and were consulted on other guidance and information aspects of the project as needed. were reviewers or authors As SAN Coordinator, I heartily thank all Seth Dabney, Sharad Phatak, members of the sustainable agriculture Marianne Sarrantonio, Jim Sims, community for their cooperation in provid- John Teasdale, Mary V. Gold ing information that will strenthen our agri- (National Agricultural Library, culture for future generations. Such Beltsville, Md.), Aref Abdul-Baki cooperation is truly the hallmark of the (USDA/ARS, Beltsville, Md.) and sustainable agriculture movement. Robert Bugg (University of California, Davis, Calif.). Andy Clark, Coordinator The USDA Sustainable Agriculture Sustainable Agriculture Network Research and Education (SARE) program Beltsville, Md. funded the project as part of its May, 1998

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

4 MANAGING COVER CROPS PROFITABLY FOREWORD

over crops slow erosion, improve soil, with great potential as cover crops in particular smother weeds, enhance nutrient and climates or cropping systems are accessible Cmoisture availability, help control many through publications and cover crop experts list- pests and bring a host of other benefits to your ed in the appendices. farm. At the same time, they can reduce costs, Many of the proven species described in the increase profits and even create new sources of book may be more familiar as forage or cash income.You’ll reap dividends on your cover crop crops.These crops have been adapted for use as investments for years,because their benefits accu- cover crops, which, strictly speaking, are not mulate over the long term. harvested. Our primary intent in this book is to Cover crops can make you a better neighbor, describe the use of these crops as cover crops. too. They prevent nutrient leaching and runoff, Because economics plays a major role in deciding and reduce or eliminate the off-site impacts of which crops farmers include in their rotations,we herbicides and pesticides. do mention some important alternative uses that There is a cover crop to fit just about every make growing cover crops even more rewarding. farming situation.The purpose of this book is to If you plant one of these cover crops and want help you find which ones are right for you. the option to harvest it as a cash crop, consult Since the Sustainable Agriculture Network other resources for more complete information. (SAN) published Managing Cover Crops We have tried to include enough information Profitably in 1992, more and more farmers have for you to select and use cover crops appropriate tried cover crops and are researching their use in to your operation.We recommend that you define farming systems. Other research by university your reasons for growing a cover crop—the sec- and government scientists, agricultural profes- tion, Selecting the Best Cover Crops for Your sionals and numerous farm organizations has Farm (p. 30) can help with this—and take as contributed more information about how cover much care in selecting and managing cover crops crops can enhance traditional cropping systems. as you would a cash crop. This book distills published and unpublished Regional and site-specific factors can compli- cover crop experiences into a reader-friendly cate cover crop management. No book can ade- reference tool for use by farmers and agricultural quately address all the variables that make up a professionals. Our writers reviewed published crop production system. Before planting a cover literature in scientific journals and talked with crop,learn as much as you can from this book and farmers and researchers using cover crops. The talk to others who are experienced with that dedicated help of a knowledgeable editorial board cover crop. Consult state and local resources for and reviewers throughout the country rounded specific information about adaptation and man- out the book. agement of a cover crop in your area. See also A publication of this scope cannot possibly Recommended Resources (p. 162). describe all the cover crops currently in use.We We hope that this updated and greatly expand- have selected the most proven crops with the ed edition of Managing Cover Crops Profitably widest possible application in the continental will lead to the successful use of cover crops on United States. Because of space and time limita- a wider scale as we continue to increase the tions, several very promising species were omit- sustainability of our farming systems. ted or not given complete coverage. Some of these are mentioned in Appendix B, Up-and- Andy Clark, Coordinator Coming Cover Crops (p.158).Many other species Sustainable Agriculture Network (SAN) May, 1998

FOREWORD 5 MANAGING COVER CROPS PROFITABLY SECOND EDITION

Acknowledgments...... 3 Berseem Clover ...... 87 Foreword...... 5 • Crimson-Berseem Clover Combo How to Use ...... 7 Works as Corn Underseeding ...... 89 Benefits of Cover Crops...... 9 • Nodulation: Match Inoculant to Selecting the Best Cover Crops Maximize N...... 92 for Your Farm...... 12 Cowpeas ...... 95 Building Soil Fertility and Tilth • Cowpeas Provide Elegant Solution with Cover Crops ...... 16 to Awkward Niche ...... 98 • Cover Crops Can Stabilize Your Soil . . . 19 Crimson Clover ...... 100 • How Much N? ...... 22 Field Peas ...... 105 Managing Pests with Cover Crops ...... 25 • Peas Do Double Duty • Georgia Cotton, Peanut Farmers for Kansas Farmer ...... 110 Use Cover Crops to Control Pests...... 26 Hairy Vetch ...... 112 • Select Covers that Balance Pests, • Vetch Beats Plastic ...... 118 Problems of Farm ...... 30 Medics...... 119 Crop Rotations with Cover Crops ...... 34 • Jess Counts on GEORGE for N and • Full-Year Covers Tackle Tough Weeds. . . 38 Organic Matter...... 121 Overview of Charts ...... 43 • Southern Spotted Bur Medic Offers Chart 1:Top Regional Cover Crop Species. . . 47 Reseeding Persistence ...... 122 Chart 2: Performance and Roles...... 48 Red Clover...... 127 Chart 3A: Cultural Traits...... 50 Subterranean Clover ...... 132 Chart 3B: Planting ...... 51 Sweetclover...... 139 Chart 4A: Potential Advantages ...... 52 • Sweetclover: Good Grazing, Chart 4B: Potential Disadvantages ...... 53 Great Green Manure ...... 142 White Clover ...... 147 Cover Crop Species Woollypod Vetch ...... 151 Overview of Nonlegume Cover Crops. . . 54 Annual Ryegrass ...... 55 Appendices Barley ...... 58 A.Testing Cover Crops on Your Farm...... 156 Oats...... 62 B. Up-and-Coming Cover Crops ...... 158 Cereal Rye ...... 65 C. Recommended Resources ...... 162 • Rye Smothers Weeds Before Soybeans . . 67 D. Seed Suppliers...... 166 Winter wheat ...... 72 E. Farming Organizations with • Wheat Boosts Income and Cover Crop Expertise ...... 170 Soil Protection...... 74 F.Regional Experts...... 173 • Wheat Offers High-Volume G. Citations Bibliography ...... 180 Weed Control Too ...... 75 H. Resources from the Sustainable Buckwheat ...... 77 Agriculture Network ...... 198 Sorghum Sudangrass ...... 80 I. Reader Response Form ...... 200 • Summer Covers Relieve Compaction . . 84 Overview of Legume Cover Crops ...... 85 Index ...... 201 Grass/Legume Mixtures Expand Possibilities ...... 86

6 MANAGING COVER CROPS PROFITABLY HOW TO USE THIS BOOK

hink of this book as a tool chest, not a heart of the book, the chapters on each cover cookbook.You won’t find the one simple crop. The chapters offer even more practical T recipe to meet your farming goals.You will descriptions of how to plant, manage, kill and find the tools to select and manage the best cover make the best use of each species. crops for the unique needs of your farm. Don’t overlook Up-and-Coming Cover Crops In this tool chest you will find helpful maps and (p. 158) that briefly describes promising but charts, detailed narratives about individual cover lesser known cover crops. One of them may be crop species, chapters about specific aspects of right for your farm. cover cropping and extensive appendices that will lead you to even more information. 3. With some particular cover crops in mind, The entire text of Managing Cover Crops step back and look at the big picture of how you Profitably, 2nd Edition is available on CD-ROM. can fit cover crops into your farming operations. The electronic version is a great resource for agri- Sit down with a highlighter and explore these cultural educators and computer-savvy producers chapters: because it allows users to search for crops with • Benefits of Cover Crops (p. 9) explains one click of the mouse—and download sections important cover crop roles such as reducing into new files for presentations and fact sheets. costs, improving soil and managing pests. To order, see p. 199. • Selecting the Best Cover Crops (p. 12) helps you evaluate your operation’s needs and niches 1. Start with Top Regional Cover Crop Species (seasonal, cash-crop related, and profit potential). (p. 47). This chart will help you narrow your Several examples show how to fit crops to search by listing the benefits you can expect from detailed situations. the top cover crops adapted to your region.You’ll • Building Soil Fertility and Tilth (p. 16) discover which are the best nitrogen (N) sources, shows how cover crops add organic matter and soil builders, erosion fighters, subsoil looseners, greater productivity to the biological, chemical weed fighters and pest fighters. 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 you want to Cover Crops (p. 25) try. The Appendices explores how cover include information crops change field to help you run reli- environments to able on-farm cover protect cash crops crop comparison from insects, dis- trials. You’ll also ease, weeds and find contact infor- nematodes. mation for cover • Crop Rotations crop experts in your (p. 34) explains how to region, seed suppliers integrate cover crops and and inoculant providers, cash crops in sequence from references to books and other year to year for optimum produc- academic papers cited in this book tivity from on-farm resources. and World Wide Web resources with more • Citations Bibliography (p. 180) lists many of cover crop information. the publications and specialists cited in the book. Citations within the book are numbered in paren- 5. Finally,share your cover crop plans with farmers theses. Refer to the numbered citation in the bib- in your area who have experience with cover liography if you want to dig deeper into a topic. crops. Your local Extension staff, regional IPM • Climatic Zone Maps inside the front and specialist or a sustainable farming group in your back covers help you understand differences in area may be able to provide contacts.Be sure to tap cover crop performance from location to loca- local wisdom.You can find out the cover crop prac- tion. You may find that some cover crops have tices that have worked traditionally, and the new performed well in tests far from where you farm, wrinkles or crops that innovative practitioners but under comparable climatic conditions. have discovered. The USDA Plant Hardiness Zone Map (inside front cover) shows whether a crop will Abbreviations used in this book survive the average winter in your area.We refer A = acre or acres to the USDA hardiness zones throughout the bu. = bushel or bushels book. DM = dry matter, or dry weight of plant material The U.S. Forest Service map, Ecoregions of F = (degrees) Fahrenheit the United States (inside back cover), served in. = inch or inches in part as the basis for the adaptation maps includ- K = potassium ed at the beginning of each cover crop chapter. lb. = pound or pounds This ecosystem map, while designed to classify N = nitrogen forest growth, shows localized climate differ- OM = organic matter ences, such as rainfall and elevation, within a P = phosphorus region. (See Bailey in Recommended Resources, p. = page p. 162). pp. = pages T = ton or tons 4. Now that you’ve tried out most of the tools, > = progression to another crop revisit the charts and narratives to zero in on the / = a mixture of crops growing together

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

8 MANAGING COVER CROPS PROFITABLY BENEFITS OF COVER CROPS

over crops can boost your profits the first year you plant them. They can improve C 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 eval- Legume cover crops convert nitrogen gas in uate the economic and ecological aspects of the atmosphere into soil nitrogen that plants can cover crops. These significant benefits (detailed use. See Nodulation: Match Inoculant to below) vary by location and season, but at least Maximize N (p. 92). Crops grown in fields after two or three usually occur with any cover crop. legumes can take up at least 30 to 60 percent of Consult local farming groups and agencies with the N that the legume produced.You can reduce cover crop experience to figure more precise N fertilizer applications accordingly. For more crop budgets. information on nitrogen dynamics and how to cal- • Cut fertilizer costs culate fertilizer reductions, see Building Soil • Reduce the need for herbicides and other Fertility and Tilth with Cover Crops (p. 16). pesticides The N value of legumes is the easiest cover • Improve yields by enhancing soil health crop benefit to evaluate, both agronomically • Prevent soil erosion and economically. This natural fertility input • Conserve soil moisture alone can justify cover crop use. • Protect water quality • Hairy vetch boosted yield for no-till corn • Help safeguard personal health more than enough to cover its establishment Evaluate a cover crop’s impact as you would costs, a three-year study in Maryland showed. any other crop, balancing costs against returns in Further, the vetch can reduce economic risk and all forms. Don’t limit your calculations, however, usually will be more profitable than no-till corn to the target cover crop benefit. A cover often after a winter wheat cover crop. The result has several benefits. Many cover crops offer held true even if corn were priced as low as $1.80 harvest possibilities as forage, grazing or seed per bushel, or N fertilizer was applied at the rate that work well in systems with multiple crop of 180 lb. N/A (136). enterprises and livestock. • Medium red clover companion seeded with oats and hairy vetch had estimated fertilizer SPELLING IT OUT replacement value of 65 to 103 lb. N/A in a four- year study in Wisconsin, based on a two year rota- Here’s a quick overview of benefits you can grow tion of oats/legume > corn. Mean corn grain yield on your farm. Cover crops can: following these legumes was 163 bu./A for red clover and 167 bu./A for hairy vetch, compared Cut fertilizer costs by contributing N to cash with a no legume/no N fertilizer yield of 134 crops and by scavenging and mining soil nutrients. 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 beets in a Wyoming test. Using this brassica cover NITRO alfalfa can provide 80 to 100 percent of a crop after malting barley or silage corn substitut- subsequent potato crop’s nitrogen requirement, a ed profitably for chemical nematicides when study in the Pacific Northwest showed (322). nematode levels were moderate (184). • Fibrous-rooted cereal grains or grasses are A corn>rye>soybeans>wheat>hairy vetch rota- particularly good at scavenging excess nutrition that has reduced pesticide costs is at least ents—especially N—left in the soil after cash crop as profitable as conventional grain rotations harvest. Much of the N is without cover crops, an on- held within the plants until To estimate your potential going study in southeastern they decompose. Fall-seeded Pennsylvania shows (137). grains or grasses can absorb N fertilizer savings from a Fall-planted brassica cover up to 71 lb. N/A within three cover crop, see the sidebar, crops coupled with mechan- months of planting, a Mary- ical cultivation help potato land study showed (30). How Much N? (p. 22). growers with a long growing Addition of cover crops to season maintain marketable corn>soybean and corn>peanut>cotton rotations yield and reduce herbicide applications by 25 and appropriate timing of fertilizer application percent or more, a study in the inland Pacific usually reduce total N losses, without causing Northwest showed (322). yield losses in subsequent crops, a USDA-ARS computer modeling study confirms (293). Improve Yields by Enhancing Soil Health Cover crops improve soil by: Reduce the Need for Herbicides • Speeding infiltration of excess surface water Cover crops suppress weeds and reduce damage • Relieving compaction and improving structure by diseases, insects and nematodes. of overtilled soil Many cover crops effectively suppress weeds as: • Adding organic matter that encourages • A smother crop that outcompetes weeds for beneficial soil microbial life water and nutrients • Enhancing nutrient cycling • Residue or growing leaf canopy that blocks Building Soil Fertility and Tilth with Cover light, alters the frequency of light waves and Crops (p. 16) details the biological and chemical changes soil surface temperature processes of how cover crops improve soil health • A source of root exudates or compounds that and nutrient cycling. Leading soil-building crops provide natural herbicidal effects include rye (residue adds organic matter and Managing Pests with Cover Crops (p. 30) conserves moisture); sorghum-sudangrass (deep describes how cover crops can: penetrating roots can break compaction); and • Host beneficial microbial life that discourages ryegrass (stabilizes field roads,inter-row areas and disease borders when soil is wet). • Create an inhospitable soil environment for many soilborne diseases Prevent Soil Erosion • Encourage beneficial insect predators and Quick-growing cover crops hold soil in place, parasitoids that can reduce insect damage reduce crusting and protect against erosion due below economic thresholds to wind and rain. The aboveground portion of • Produce compounds that reduce nematode covers also helps protect soil from the impact of pest populations raindrops. Long-term use of cover crops increases • Encourage beneficial nematode species water infiltration and reduces runoff that can Using a rotation of malting barley>cover crop carry away soil. radish>sugar beets has successfully reduced sugar The key is to have enough stalk and leaf growth beet cyst nematodes to increase yield of sugar to guard against soil loss. Succulent legumes

10 MANAGING COVER CROPS PROFITABLY decompose quickly, especially in warm weather. living plants drawing too much moisture from the Winter cereals and many brassicas have a better soil in dry years. chance of overwintering in colder climates.These late-summer or fall-planted crops often put on sig- Protect Water Quality nificant growth even when temperatures drop By slowing erosion and runoff, cover crops into the 50s,and often are more winter-hardy than reduce nonpoint source pollution caused by legumes (302). sediments, nutrients and agricultural chemicals. In a no-till cotton system, use of cover crops By taking up excess soil nitrogen, cover crops such as winter wheat, crimson clover and hairy prevent N leaching to groundwater. Cover crops vetch can reduce soil erosion while maintaining also provide habitat for wildlife. high cotton yields, a Mississippi study shows (21). A rye cover crop scavenged from 25 to 100 percent of residual N from conventional and Conserve Soil Moisture no-till Georgia corn fields, one study showed. Up Residue from killed cover crops increas- to 180 lb. N/A had been applied. A barley es water infiltration and reduces evap- cover crop removed 64 percent of soil nitrogen oration, resulting in less moisture when applied N averaged 107 lb./A (177). stress during drought. Lightly incorporated cover crops serve Help Safeguard Personal Health dual roles. They trap surface By reducing reliance on agrichemi- water and add organic matter to cals for cash crop production, increase infiltration to the root cover crops help protect the zone. Especially effective at health of your family, neighbors covering the soil surface are and farm workers.They also help grass-type cover crops such as address community health and rye, wheat, and sorghum- ecological concerns arising from Sudangrass hybrid. Some water-effi- nonpoint source pollution attributed cient legumes such as medic and to farming activities. INDIANHEAD lentils provide cover crop benefits in dryland areas while Cumulative Benefits conserving more moisture than conven- You can increase the range of benefits tional bare fallow (316). by increasing the diversity of cover Timely spring termination of a cover crops grown, the frequency of use crop avoids the negative impact of between cash crops and the length of opposite water conditions: excess time that cover crops are growing in residue holding in too much mois- the field. ture for planting in wet years, or

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

over crops provide many benefits, paper.For each field,pencil in current or probable but they’re not do-it-all “wonder crops.” rotations, showing when you typically seed crops CTo find a suitable cover crop or mix and when you harvest them. If possible, sketch in of covers: a rough graph showing average daily temperature • Clarify your primary needs during the timeline, and another for average rain- • Identify the best time and place for a cover fall.Add other key information, such as frost-free crop in your system periods and times of heavy labor or equipment • Test a few options demand. This book makes selection of cover crops a lit- Look for open periods in each field, open tle easier by focusing on some proven ones. spaces on your farm or opportunities in your sea- Thousands of species and varieties exist,however. sonal work schedule. Also consider ways to The steps that follow can help you find crops that extend or overlap cropping windows. will work best with a minimum of risk and Here are examples of common niches in some expense. systems, and some tips:

1. Identify Your Problem or Use Winter fallow niche. In many regions,seed win- Review Benefits of Cover Crops (p. 9) to decide ter covers at least six weeks before a hard frost. what you want most from a cover crop. This Winter cereals are an exception and can be plant- simplifies your search. ed a little later.If ground cover needs are minimal, Some common goals for covers are to: plant rye until the frost period for successful over- • Provide nitrogen wintering, although N recycling will be limited. • Add organic matter You might seed a cover right after harvesting a • Improve soil structure summer crop, when the weather is still mild. In • Reduce soil erosion cooler climates, consider extending the window • Provide weed control by overseeding (some call this underseeding) a • Manage nutrients shade-tolerant cover before cash crop harvest. • Furnish moisture-conserving mulch White clover, annual ryegrass, rye, hairy vetch, Having one or two secondary goals can narrow crimson clover, red clover and sweetclover toler- the hunt when comparable covers could satisfy a ate some shading. primary role. You might want habitat for benefi- If overseeding, irrigate immediately if possible, cial organisms, better traction during harvest, or seed just before a soaking rain. Species with faster drainage or another benefit. small, round seeds, such as clovers, don’t need a lot of moisture to germinate and can work their 2. Identify the Niche way through tiny gaps in residue. Sometimes it’s obvious where and when to use a If you want to harvest a cereal grain cover crop, cover crop.You might want some nitrogen before interseeding a legume might increase disease a corn crop,or a perennial ground cover in a vine- risks due to lower air circulation or insect pest yard or orchard to reduce erosion or improve risk,so plan accordingly.Changing seeding rate or weed control. For some goals, such as building the rotation sequence may lessen this risk. soil, it may be hard to decide where and when to To ensure adequate sunlight for the cover crop, schedule cover crops. overseed before full canopy closure of the primary Look at your rotation first. Make a timeline of crop (at last cultivation of field corn, for example) 18 to 24 monthly increments across a piece of or a few weeks before the cash crop starts to die.

12 MANAGING COVER CROPS PROFITABLY Expect excessive field traffic around harvest- Properly managed, living mulches give many time? Choose tough, low-growing covers such growers year-round erosion protection,weed con- as grasses or clovers. Limit traffic or delay a field trol, nutrient cycling and even some nitrogen if operation to allow for cover crop establishment. they include a legume. Some tillage, mowing or Another option could be a reseeding winter herbicides can help manage the mulch (to keep it annual that dies back and drops seed each spring from using too much soil moisture, for example) but reestablishes in fall. Subclovers reseed well before crops are strip-tilled into the cover or in regions south of Hardiness Zone 6. Shorter- residue.White clover could be a good choice for season crimson clovers—especially varieties with sweet corn and tomatoes. Perennial ryegrass or a high hard-seed percentage that germinate over other nonaggressive turfgrasses work for beans, an extended period—work well in the Southeast tomatoes and other vegetables. where moisture is sufficient. Creating new niches. Have you honed a rota- Summer fallow niche. Many vegetable rotation that seems to have few open time slots? Plant tions present cover crop opportunities—and a cover in strips alternating with your annual veg- challenges. When double cropping, you might etable, herb or field crop. Switch the strips the have fields with a three- to eight-week summer next year. Mow the strips periodically and blow fallow. Quick-growing summer the topgrowth onto adjoining annuals provide erosion control, Look for open periods cash crops as mulch. In a bed weed management, organic mat- system, rotate out every third or ter and perhaps some N. in each field or open fourth bed for a soil-building Consider overseeding into a spaces on your farm. cover crop. spring crop with buckwheat, Another option: Band a cover millet or sorghum-Sudangrass, or or some insect-attracting shrubs a warm-season legume such as cowpeas. Or till around fields or along hedgerows to suppress out strips in the cover crop for planting a fall weeds or provide beneficial habitat where you vegetable crop and control the remaining cover can’t grow cash crops. between the crop rows with mowing, partial cultivation or herbicide spraying. 3. Describe the Niche Refer to your timeline chart and ask questions Small grain rotation niche. Companion seed a such as: winter annual cover crop with a spring grain, • How will I seed the cover? or frost seed a cover into winter grains. Soil • What’s the weather likely to be then? freezing and thawing pulls seed into the soil and • What will soil temperature and moisture helps germination. Another option if soil conditions be like? moisture isn’t a limiting factor in your region: • How vigorous will other crops (or pests) be? broadcast a cover before the grain enters boot • Should the cover be low-growing and stage (when seedheads start elongating) later in spreading, or tall and vigorous? spring. • What weather extremes and field traffic must it tolerate? Full-year improved fallow niche. To rebuild • Will it winterkill in my area? fertility or organic matter over a longer period, • Should it winterkill, to meet my goals? perennials or biennials—or mixtures—require • What kind of regrowth can I expect? the least maintenance. Spring-seeded yellow • How do I kill it and plant into it? blossom sweetclover flowers in summer of • Will I have the time to make this work? Year 2, has a deep taproot and gives plenty of • What’s my contingency plan—and risks—if the aboveground biomass. Also consider perennial crop doesn’t establish or doesn’t die on schedule? forages recommended for your area. • Do I have the needed equipment and labor?

SELECTING THE BEST COVER CROPS 13 4. Select the Best Cover Crop ing, reseeding grasses often suitable for orchard You have a goal and a niche. Now specify the floors. One of these might fill the bill with a traits a cover crop would need to work well. reseeding, winter annual legume such as crimson clover, rose clover, subclover, an annual vetch or Example 1. A sloping orchard needs a ground an annual medic, depending on your climate. cover to reduce erosion. You’d like it to contribute N and organic matter and attract ben- Example 2. A dairy lacks adequate storage in eficial organisms but not rodents,nematodes or fall and winter for the manure it generates, other pests. The cover can’t use too much which exceeds the nutrient needs for its silage water or tie up nutrients at key periods. Too corn and grass/legume hay rotation. much N might stimulate excessive leaf growth or The cover crop needs to: prevent hardening off before winter. Finally you • establish effectively after (or tolerate) silage want easy maintenance. corn harvest The cover crop should: • take up a lot of N and P in fall and hold it until • be a perennial or reseeding annual spring • be low-growing, needing minimal management For this dairy scenario, rye is often recom- • use water efficiently mended. Other cereal grains or brassicas could • have a soil-improving root system work if planted early enough. • release some nutrients during the year, but not too much N Example 3. In a moderate rainfall region after • not harbor or attract pests small grain harvest in late summer, you want For this orchard scenario, white clover is a soil-protecting winter cover that can supply probably the best option north of Zone 8. A N for no-till corn next spring. You want to kill mixture of low-growing legumes or a legume and the cover without herbicides. grass mix could also work. In warm regions, low- You need a legume that: growing clovers such as strawberry clover and • can be drilled in late summer and put on a lot white clover work well together, although these of fall growth species may attract pocket gophers. BLANDO • will overwinter brome and annual ryegrass are two quick-grow- • 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 weed- management 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.

14 MANAGING COVER CROPS PROFITABLY 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.

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 Example 4. After a spring broccoli crop, you cover crop’s strengths help you decide which need a weed-suppressing cover that adds N cash crops would benefit the most. and organic matter, and perhaps mulch, into For now,however,you probably want to fit one which you will no-till seed fall lettuce or spinach. or more cover crops into your existing rotations. You want a cover that: The charts and narratives in this book can help • is very versatile you select some of the most suitable species for • grows fast in hot weather your farming system and objectives. See Crop • can be overseeded into broccoli Rotations with Cover Crops (p. 34) to get you • germinates on the soil surface under dry thinking more. When you’ve narrowed your conditions choices, refer to Appendix A, Testing Cover Crops • fixes N on Your Farm (p. 156) for some straightforward • persists until you’re ready to kill it tips on what to do next. Here, a quick-growing, warm-season legume such as cowpeas may work, especially if you can irrigate Adapted from Northeast Cover Crop Handbook to hasten establishment during dry conditions. 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 by Marianne Sarrantonio

oil is an incredibly complex substance. It has EROSION PROTECTION physical and chemical properties that allow Sit to sustain living organisms—not just plant Erosion of topsoil occurs on many farms, depriv- roots and earthworms,but hundreds of thousands ing fields of the most fertile portion that contains of different insects, wormlike creatures and the highest percentage of organic matter and microorganisms. When these organisms are in nutrients. Cover crops can play a major role in balance, your soil cycles nutrients efficiently, fighting soil erosion. stores water and drains the excess, and maintains A raindrop falling at high speed can dislodge an environment in which plants can thrive. soil particles and cause them to move as far as 6 To recognize that a soil can be healthy, one feet (28). Once a soil particle is loose, it is much has only to think of the soil as a living entity. It more vulnerable to being carried away by breathes, it transports and transforms nutrients, it running water. Any aboveground soil cover can interacts with its environment, and it can even puri- take some of the punch out of a heavy rainfall fy itself and improve over time. If you view soil as a simply by acting as a cushion for raindrops. dynamic part of your farming system, unsustainable A cover crop also can: crop management practices amount to soil neglect. • Slow the action of moving water just by That neglect could worsen as the soil sickens and creating an obstacle course of leaves, stems loses its life functions one by one. and roots through which the water must Regardless of how healthy or alive your soil is maneuver on its way downhill right now, cover crops can play a vital role in • Increase the soil’s ability to absorb and hold ensuring that your soil provides a strong founda- water, thereby preventing large quantities of tion for your farming system. While the most water from moving across the soil surface common reasons for including cover crops in • Help stabilize soil particles in the cover crop a farming system may relate to the current root system season, the continued practice of cover cropping The reduction in soil erosion due to cover becomes an investment in building healthy soil cropping will be roughly proportional to the over the long term. amount of cover on the soil. The Universal Soil Cover crops improve soil in a number of ways. Loss Equation developed by the USDA Soil Protection against soil loss from erosion is per- Conservation Service (now the Natural Resources haps the most obvious soil benefit of cover crops, Conservation Service) predicts that a soil cover of but providing organic matter is a more long-term just 40 percent when winter arrives can reduce and equally important goal. Cover crops con- erosion substantially until spring. tribute indirectly to overall soil health by catching It’s worthwhile to get covers established early, nutrients before they can leach out of the soil pro- to ensure that maximum soil cover develops file or by adding nitrogen to the soil.Their roots before winter rains. Consider overseeding covers can even help unlock some nutrients, converting at layby cultivation, aerial seeding before harvest them to more available forms. Cover crops pro- or planting as soon as possible after harvest. It’s vide habitat or a food source for some important also a good idea to maintain year-round soil cover soil organisms, break up compacted layers in the whenever possible. soil and help dry out wet soils.

16 MANAGING COVER CROPS PROFITABLY ORGANIC MATTER ADDITIONS After the microorganisms have devoured the portions of the active fraction that are easiest to The benefits of organic matter include improved digest, a more dedicated subset of these microor- soil structure, increased infiltration and ganisms will start munching on the more com- water-holding capacity, increased cation plex and tough material, such as celluloses and exchange capacity (the ability of the soil to act lignins,the structural materials of plants.Since cel- as a short-term storage bank for positively charged lulose is tougher than simple sugars, and lignin plant nutrients) and more efficient storage of breaks down very slowly,they contribute more to nutrients. Without organic matter, you have no the humus or stable fraction. Humus is responsi- soil to speak of, only a dead mixture of ground-up ble for giving the soil that rich, dark, spongy feel- and weathered rocks. ing and for properties such as water retention and Organic matter includes thousands of different cation exchange capacity. substances derived from decayed leaves, roots, Plant materials that are succulent and rich microorganisms, manure and even groundhogs in proteins and sugars will release nutrients rapid- that died in their burrows. These substances ly but leave behind little long-term organic matter. function in different ways to build healthy soil. Plant materials that are woodier or more Different plants leave behind different kinds of fibrous will release nutrients much more slowly, organic matter as they decompose,so your choice but will promote more stable organic matter, or of cover crop will largely determine which soil humus, leading to better soil physical conditions, benefits you will receive. increased nutrient-holding capacity and higher Soil scientists may argue over how to classify cation exchange capacity. the various soil organic components. Most will In general, annual legumes are succulent. agree, however,that there is a portion that can be They release nitrogen and other nutrients quick- called the “active” fraction, and one that might ly through the active fraction, but are not very be called the “stable” fraction, which is roughly effective at building up humus. Long-term use equivalent to humus.There are many categories of succulent annual legumes can increase in between the active and stable fractions. soil humus, however, as recent research The active fraction represents the most easily suggests (354). decomposed parts of soil organic matter. It tends Grains and other grasses and nonlegumes will to be rich in simple sugars and proteins and contribute to humus production, but won’t consists largely of recently added residues, micro- release nutrients very rapidly or in large bial cells and the simpler waste products from quantities if incorporated as they approach matu- microbial decay. rity. Perennial legumes such as white and red Because microorganisms, like human organ- clover may fall in both categories—their leaves isms, crave sweet stuff, compounds containing will break down quickly, but their root systems simple sugars disappear quickly. Proteins also are may become tough and fibrous and can con- selected quickly from the menu of edible soil tribute to humus accumulation. goodies. When these compounds are digested, many of the nutrients that they contain are Cover Crops Help “Glue” Soil released into the soil. Proteins are nitrogen-rich, As soil microorganisms digest plant material, they so the active fraction is responsible for the produce some compounds in addition to the release of most N, as well as some K, P and other active and stable fractions of the organic matter. nutrients, from organic matter into the soil. One group of these by-products is known as The easily decomposed proteins and sugars burn polysaccharides.These are complex sugars that up almost completely as energy sources, and act as glues in the soil to cement small soil parti- don’t leave much behind to contribute to organic cles into clusters or aggregates. Many farmers matter building. use the term “crumb” to describe soil clusters

BUILDING SOIL FERTILITY AND TILTH 17 about the size of a grain of rice. A well- down of soil aggregates and the poor soil struc- aggregated or “crumby” soil—not to be confused ture often seen in overtilled soil. with someone else’s crummy or depleted soil— When adding cover crops to a system, mini- has good aeration. It allows better infiltration and mize tillage to maximize the long-term soil bene- retention of water. fits. Many of the cover crops discussed in this Cover crops can promote good aggregation in book are ones you can seed into growing crops or the soil through increased production of these no-till plant into crop residues. Otherwise, the and other microbial glues, recent research has gain in organic matter may be counteracted by shown. See Cover Crops Can Stabilize Your Soil higher decomposition rates. (p. 19). Well-aggregated soils also are less prone to compaction, which has been shown to reduce TIGHTENING THE NUTRIENT LOOP yields of vegetables such as snap beans, cabbage and cucumber by 50 percent or more (371). In addition to reducing topsoil erosion and improv- As they decompose, leguminous cover crops ing soil structure, cover crops enhance nutrient seem to be better than grasses for production of cycling in your farming system by taking up nutri- polysaccharides (6). However, polysaccharides ents that otherwise might leach out of the soil pro- will decompose in a matter of months, so their file. These excess nutrients have the potential to aggregation effect is likely to last only the season pollute groundwater or local streams and ponds. after the use of the cover crop. Of the common plant nutrients, nitrogen in the Grass species also promote good aggregation, nitrate form is the most water-soluble and there- but by a different mechanism. Grasses have a fore the most vulnerable to leaching. Anytime ‘fibrous’ root system—made of numerous fine soil is bare and appreciable rain falls, nitrates are roots spreading out from the base of the plant. on the move. Nitrate can be present in the soil These roots may release compounds that help at the end of a cropping season if the crop did not aggregate the soil between roots. use all the N applied. Decomposing organic mat- Organic matter builds up very slowly in the ter (including plant residues, compost and animal soil. A soil with 3 percent organic matter might manures) also can release nitrate-N, as long as the only increase to 4 percent after a decade or soil temperature is above freezing. Even in a field more of soil building. The benefits of increased where the yearly application of N is well-suited to organic matter, however, are likely to be apparent crop needs, nitrates can accumulate after crops long before increased quantities are detectable. are harvested and leach when it rains. Some, such as enhanced aggregation, water infil- Cover crops reduce nitrate leaching in two tration rates and nutrient release,will be apparent ways. They soak up available nitrate for their the first season; others may take several years to own needs. They also use some soil moisture, become noticeable (354). reducing the amount of water available to leach Your tillage method is an important considera- nutrients. tion when using cover crops to build soil,because The best cover crops to use for nitrate conser- tillage will affect the rate of organic matter accu- vation are nonlegumes that form deep, extensive mulation. It is difficult to build up organic root systems quickly after cash crops are matter under conventional tillage regimes. harvested. For much of the continental U.S., cere- Tillage speeds up organic matter decomposition al rye is the best choice for catching nutrients by exposing more surface area to oxygen, warm- after a summer crop. Its cold tolerance is a big ing and drying the soil, and breaking residue into advantage that allows rye to continue to grow in smaller pieces with more surfaces that can be late fall and put down roots to a depth of three attacked by decomposers. Like fanning a fire, feet or more. Where winters are mild, rye can tillage rapidly “burns up” or “oxidizes” the fuel, grow through the winter months. which in this case is organic matter. The Research with soil high in residual N in the resulting loss of organic matter causes the break- mid-Atlantic’s coastal plain showed that cereal rye

18 MANAGING COVER CROPS PROFITABLY Cover Crops Can Stabilize Your Soil The more you use cover crops, the better phosphorus that plants obtain. In return, the your soil tilth, research continues to show. fungi receive energy in the form of sugars One reason is that cover crops, especially that plants produce in their leaves and send legumes, encourage populations of beneficial down to the roots. fungi and other microorganisms that help Growing a cover crop increases the bind soil aggregates. abundance of mycorrhizal spores. Legumes The fungi, called mycorrhizae, produce a in particular can contribute to mycorrhizal water-insoluble protein known as glomalin, diversity and abundance, because their roots which catches and glues together particles of tend to develop large populations of these organic matter, plant cells, bacteria and other beneficial fungi. fungi, recent research suggests (372). By having their own mycorrhizal fungi and Glomalin may be one of the most important by promoting mycorrhizal relationships in substances in promoting and stabilizing soil subsequent crops, cover crops therefore can aggregates. play a key role in improving soil tilth.The Most plant roots, not just those of cover overall increase in glomalin production also crops, develop beneficial mycorrhizal could help explain why cover crops can relationships.The fungi send out rootlike improve water infiltration into soil and extensions called hyphae, which take up enhance storage of water and soil nutrients, water and soil nutrients to help feed plants. even when there has been no detectable In low-phosphorus soils, for example, the increase in the amount of soil organic hyphae can increase the amount of matter.

took up more than 70 lb. N/A in fall when plant- nutrients can be brought up from deeper soil lay- ed by October 1. Other grasses, including wheat, ers by any deep-rooted cover crop.The nutrients oats, barley and ryegrass, were only able to take are then released back into the active organic mat- up about half that amount in fall. Legumes were ter when the cover crop dies and decomposes. practically useless for this purpose in the Although phosphorus (P) doesn’t generally Chesapeake Bay study (30). Legumes tend to leach, as it is only slightly water-soluble, cover establish slowly in fall and are mediocre N crops may play a role in increasing its availability scavengers, as they can fix much of their own N. in the soil. Some covers, such as buckwheat and To maximize N uptake and prevent leaching, lupins, are thought to secrete acids into the soil plant nonlegumes as early as possible. In the that put P into a more soluble, plant-usable form. above study, rye took up only 15 lb. N/A when Some cover crops enhance P availability in planting was delayed until November. It is impor- another manner. The roots of many common tant to give cover crops the same respect as any cover crops, particularly legumes, house benefi- other crop in the rotation and plant them in a cial fungi known as mycorrhizae. The mycor- timely manner. rhizal fungi have evolved efficient means of absorbing P from the soil, which they pass on to Not Just Nitrogen Cycling their plant host.The filaments (hyphae) of these Cover crops help bring other nutrients back into fungi effectively extend the root system and help the upper soil profile from deep soil layers. the plants tap more soil P. Calcium and potassium are two macronutrients Keeping phosphorus in an organic form is the with a tendency to travel with water, though not most efficient way to keep it cycling in the soil. generally on the express route with N. These So the return of any plant or animal residue to the

BUILDING SOIL FERTILITY AND TILTH 19 soil helps maintain P availability. Cover crops equal—some are genetically inferior when it help retain P in your fields by reducing erosion. comes to fixation. Beans (Phaseolus spp.) are notoriously incapable of a good symbiotic rela- Adding Nitrogen tionship and are rarely able to fix much more than One of nature’s most gracious gifts to plants and 40 lb. N/A in a whole season. Cowpeas (Vigna soil is the way that legumes, with the help of rhi- unguiculata) and vetches (Vicia spp.), on the zobial bacteria, can add N to enrich your soil. If other hand, are generally capable of high fixation you are not familiar with how this remarkable rates. Check Chart 2 Performances and Roles process works, see Nodulation: Match Inoculant (p. 48) and the sections on individual cover crops to Maximize N (p. 92). for information about their N-fixation potential. The nitrogen provided by N-fixation is used Even under the best of conditions, legumes efficiently in natural ecosystems, thanks to the rarely fix more than 80 percent of the nitrogen soil’s complex web of interacting physical, chem- they need to grow,and may only fix as much as 40 ical and biological processes. In an agricultural or 50 percent. The legume removes the rest of system, however, soil and crop management what it needs from the soil like any other plant. factors often interfere with nature’s ultra-efficient Legumes have to feed the bacteria to get them to use of organic or inorganic N. Learning a bit work, so if there is ample nitrate already available about the factors affecting N-use efficiency from in the soil,a legume will remove much of that first legume plants will help build the most sustainable before expending the energy to get N-fixation cropping system possible within your constraints. going. In soils with high N fertility, legumes may fix little or no nitrogen.See How Much N? (p.22). How Much N is Fixed? While it is tempting to think of legume nodules A number of factors determine how much of the as little fertilizer factories pumping N into the N in your legume came from “free” N, fixed from surrounding soil, that isn’t what happens. The N2 gas: fixed N is almost immediately shunted up into the • Is the symbiosis (the interdependence of stems and leaves of the growing legume to form the rhizobia and the plant roots) effective? See proteins, chlorophyll and other N-containing Nodulation: Match Inoculant to Maximize N (p. compounds.The fixed nitrogen will not become 92). Use the correct rhizobial inoculant for the available to the next crop until the legume legume you’re growing. Make sure it’s fresh, was decomposes. Consequently, if the aboveground stored properly, and that you apply it with an part of the legume is removed for hay,the majori- effective sticking agent. Otherwise, there will be ty of the fixed nitrogen also leaves the field. few nodules and N-fixation will be low. What about the legume roots? Under condi- • Is the soil fertile? N-fixation requires iron, sul- tions favoring optimal N fixation, a good rule of fur and molybdenum to function properly. Soils thumb is to think of the nitrogen left in the plant depleted of these micronutrients will not support roots (15 to 30 percent of plant N) as being efficient fixation. Tissue testing your cash crops roughly equivalent to the amount the legume can help you decide if you need to adjust removed directly from the soil, and the amount in micronutrient levels. the stems and leaves as being equivalent to what • Is the soil getting enough air? N-fixation was fixed. requires that N-rich air get to the legume roots. Annual legumes that are allowed to flower and Waterlogging or compaction hampers the move- mature will transport a large portion of their ment of air into the soil. Deep-rooted cover crops biomass nitrogen into the seeds or beans. Also, can help alleviate subsoil compaction (371). once the legume has stopped actively growing, it • Is the pH adequate? Rhizobia generally will will shut down the N-fixing symbiosis. In annual not live long in soils below pH 5. legumes this occurs at the time of flowering; no • Does the legume/rhizobial pair have high fix- additional N gain will occur after that point. ation potential? Not all legumes were created Unless you want a legume to reseed itself, it’s

20 MANAGING COVER CROPS PROFITABLY generally a good idea to kill a legume cover crop when 60 percent of the soil pores are filled in the early- to mid-blossom stage. You’ll have with water, and declines significantly when mois- obtained maximum legume N and need not delay ture levels are higher or lower (193). This 60 planting of the following cash crop any further, percent water-filled pore space roughly corre- aside from any period you may want for sponds to field capacity, or the amount of water residue decomposition as part of your seedbed left in the soil when it is allowed to drain for 24 preparation. hours after a good soaking rain. Microbes are sensitive to soil chemistry as well. How Nitrogen is Released Most soil bacteria need a pH of between 6 and 8 How much N will soil really acquire from a to perform at peak;fungi (the slow decomposers) legume cover crop? Let’s take it from the point of are still active at very low pH.Soil microorganisms a freshly killed, annual legume, cut down in its also need most of the same nutrients as plants prime at mid-bloom. The management and require, so low-fertility soils support smaller pop- climatic events following the death of that legume ulations of primary decomposers, compared with will greatly affect the amount and timing of N high-fertility soils. Don’t expect N-release rates or release from the legume to the soil. fertilizer replacement values for a given cover Most soil bacteria will feast on and rapidly crop to be identical in fields of different fertility. decompose green manures such as annual Many of these environmental factors are out of legumes, which contain many simple sugars and your direct control in the near term. Management proteins as energy sources. Soil bacteria love to factors such as fertilization, liming and tillage, party and when there is lots to eat, they do some- however, also influence production and availabili- thing that no party guest you’ve ever invited can ty of legume N. do—they reproduce themselves, rapidly and repeatedly,doubling their population in as little as Tillage, No-Tillage and N-Cycling seven days under field conditions (246). Even a Tillage affects decomposition of plant residues in relatively inactive soil can come to life quickly a number of ways. First, any tillage increases soil with addition of a delectable green manure. contact with residues and increases the microbes’ The result can be a very rapid and large release access to them. The plow layer is a hospitable of nitrate into the soil within a week of the green environment for microbes, as they’re sheltered manure’s demise. This N release is more rapid from extremes of temperature and moisture. when covers are plowed down than when left on Second, tillage breaks the residue into smaller the surface. As much as 140 lb. N/A has been pieces, providing more edges for microbes to measured 7 to 10 days after plowdown of hairy munch. Third, tillage will temporarily decrease vetch (303). Green manures that are less protein- the density of the soil, generally allowing it to rich (N-rich) will take longer to release N. drain and therefore warm up more quickly. All Those that are old and fibrous or woody are gen- told, residues incorporated into the soil tend to erally left for hard-working but somewhat slug- decompose and release nutrients much faster gish fungi to convert slowly to humus over the than those left on the surface, as in a no-till sys- years, gradually releasing small amounts of tem.That’s not necessarily good news, however. nutrients. A real challenge of farming efficiently is to keep Other factors contribute significantly to how as much of the N as possible in a stable, storable quickly a green manure releases its N. Weather form until it’s needed by the crop. The best has a huge influence. The soil organisms respon- storage form of N is the organic form: the unde- sible for decomposition work best at warm composed residue, the humus or the microorgan- temperatures and are less energetic during cool isms themselves. spring months. Let’s consider the N contained in the microbes. Soil moisture also has a dramatic effect. Nitrogen is a nutrient the microbes need for build- Research shows that soil microbial activity peaks ing proteins and other compounds. Carbon-con-

BUILDING SOIL FERTILITY AND TILTH 21 How Much N? To find out if you might need more N than If the stand has less than 100 percent your green manure supplied, you need to groundcover, multiply by (the percent ground estimate the amount of N in your cover crop. cover / 100). In this example, for 60 percent To do this, assess the total yield of the green groundcover, you would obtain: manure and the percentage of N in the plants 3,800 x (60/100) = 2,280 lb. just before they die. Keep in mind that these are rough To estimate yield, take cuttings from several estimates to give you a quick guide for the areas in the field, dry and weigh them. Use a productivity of your green manure.To know yardstick or metal frame of known dimensions the exact percent N in your plant tissue, you and clip the plants at ground level within the would have to send it to a lab for analysis. known area. Dry them out in the sun for a few Even with a delay for processing, the results consecutive days, or use an oven at about 140 could be helpful for the crop if you use split F for 24 to 48 hours until they are “crunchy applications of N.Testing is always a good idea, dry.”Use the following equation to determine as it can help you refine your N estimates for per-acre yield of dry matter: subsequent growing seasons. Yield (lb.)/Acre = Total weight of dried samples (lb.) 43,560 sq. ft. The following rules of thumb may help here: X # square feet you sampled 1 Acre • Annual legumes typically have between While actually sampling is more accurate, 3.5 and 4 percent N in their aboveground you can estimate your yield from the height of parts prior to flowering (for young material, your green manure crop and its percent use the higher end of the range), and 3 to 3.5 groundcover. Use these estimators: percent at flowering.After flowering, N in the At 100 percent groundcover and 6-inch leaves decreases quickly as it accumulates in height*, most nonwoody legumes will contain the growing seeds. roughly 2,000 lb./A of dry matter. For each * For cereal rye, the height relationship is a bit different. Cereal rye additional inch, add 150 lb. So, a legume that is weighs approximately 2,000 lb./A of dry matter at an 8-inch height 18 inches tall and 100 percent groundcover and 100 percent groundcover. For each additional inch, add 150 will weigh roughly: lb., as before, and multiply by (percent groundcover/100). For most small grains and other annual grasses, start with Inches >6: 18 in.–6 in. = 12 in. 2,000 lb./A at 6 inches and 100 percent ground cover.Add x 150 lb./in.: 12 in. x 150 lb./in. = 1,800 lb. 300 lb. for each additional inch and multiply by (percent Add 2,000 lb.: 2,000 lb. + 1,800 lb. = 3,800 lb. groundcover/100).

taining compounds such as sugars are mainly to eat. So any newly released or existing mineral energy sources, which the microorganisms use as N in soil gets scavenged by new bacteria. fuel to live. The process of burning this fuel Materials with a high carbon to nitrogen (C:N) sends most of the carbon back into the atmos- ratio, such as mature grass cover crops, straw or phere as carbon dioxide, or CO2. any fibrous, woody residue, have a low N con- Suppose a lot of new food is suddenly put into tent.They can “tie up”soil N, keeping it immo- the soil system, as when a green manure is bilized (and unavailable) to crops until the plowed down. Bacteria will expand their carbon “fuel supply” starts depleting.Tie-up may populations quickly to tap the carbon-based last for several weeks in the early part of the energy that’s available. All the new bacteria, growing season, and crop plants may show the though, will need some N, as well as other nutri- yellowing characteristic of N deficiencies. That ents,for body building before they can even begin is why it often makes sense to wait one to three

22 MANAGING COVER CROPS PROFITABLY • For perennial legumes that have a between 10 and 40 lb. N/A for each 1 percent significant number of thick, fibrous or woody organic matter. Cold, wet clays will be at the stems, reduce these estimates by 1 percent. low end of the scale and warm, well-drained • Most cover crop grasses contain 2 to 3 soils will be at the high end.You also may percent N before flowering and 1.5 to 2.5 receive benefits from last year’s manure, green percent after flowering. manure or compost application. • Other covers, such as brassicas and Other tools could help you refine your buckwheat, will generally be similar to, or nitrogen needs. On-farm test strips of cover slightly below,grasses in their N content. crops receiving different N rates would be an To put it all together: example. Refer to Appendix A, Testing Cover Total N in green manure (lb./A) = yield (lb./A) x % N Crops on Your Farm (p. 156) for some tips on 100 designing an on-farm trial. In some regions, a pre-sidedress N test in spring could help you To estimate what will be available to your estimate if supplemental N will be cost- crop this year, divide this quantity of N by: effective. Bear in mind that pre-sidedress • 2, if the green manure will be testing does not work well when fresh plant conventionally tilled; residues have been turned in—too much • 4, if it will be left on the surface in a no-till microbial interference relating to N tie-up may system in Northern climates; give misleading results. • 2, if it will be left on the surface in a no-till For more information on determining system in Southern climates. your N from green manures and other Bear in mind that in cold climates, N will amendments, see the Northeast Cover Crop mineralize more slowly than in warm climates, Handbook, or the Farmers’ Fertilizer as discussed above. So these are gross estimates Handbook, listed in Appendix C (p. 164). and a bit on the conservative side. —Marianne Sarrantonio, Ph.D. Of course, cover crops will not be the only N sources for your crops.Your soil will release

weeks after killing a low-N cover before planting and, as stated earlier, the N is mineralized more the next crop, or to supplement with a more rapidly from mixtures than from pure grass. A readily available N source when a delay is not fall-seeded mixture will adjust to residual soil N practical. levels.When the N levels are high, the grass will Annual legumes have low C:N ratios, such dominate and when N levels are low, the legume as 10:1 or 15:1. When pure stands of annual will dominate the mixtures.This can be an effec- legumes are plowed down,the N tie-up may be so tive management tool to reduce leaching while brief you will never know it occurred. making the N more available to the next crop. Mixed materials,such as legume-grass mixtures, may cause a short tie-up, depending on the C:N Potential Losses ratio of the mixture. Some N storage in the micro- A common misunderstanding about using green bial population may be advantageous in keeping manure crops is that the N is used more excess N tied up when no crop roots are there to efficiently because it’s from a plant source. This absorb it. is not necessarily true. Nitrogen can be lost from Fall-planted mixtures are more effective in a green manure system almost as easily as from immobolizing excess soil N than pure legumes chemical fertilizers, and in comparable amounts.

BUILDING SOIL FERTILITY AND TILTH 23 The reason is that the legume organic N may be release of N so it’s not as vulnerable to loss. + converted to ammonium (NH4 ), then to ammonia Consider also that some portion of the N in the - (NH3) or nitrate (NO3 ) before plants can take it up. green manure will be conserved in the soil in an Under no-till systems where killed cover crops organic form for gradual release in a number of remain on the surface, some ammonia (NH3) gas subsequent growing seasons. can be lost right back into the atmosphere. Nitrate is the form of N that most plants prefer. OTHER SOIL-IMPROVING BENEFITS Unfortunately, it is also the most water-soluble form of N. Whenever there is more nitrate than Cover crops can be very useful as living plows to plant roots can absorb, the excess may leach with penetrate and break up compacted layers in the heavy rain or irrigation water. soil. Some of the covers discussed in this book, As noted earlier, nitrates in excess of 140 lb./A such as sweetclover, have roots that reach as may be released into warm,moist soil within as lit- deep as three feet in the soil within one crop- tle as seven to 10 days after plowing down a high- ping season.The action of numerous pointy little N legume, such as a hairy vetch stand. Since the taproots with the hydraulic force of a deter- following crop is unlikely to have much of a root mined plant behind them can penetrate soil system at that point, the N has a ticket for where plowshares fear to go. Grasses, with their Leachville. Consider also that the green manure tremendously extensive root systems, may may have been plowed down to as deep as 12 relieve compacted surface soil layers. Sorghum- inches—much deeper than anyone would con- sudangrass can be managed to powerfully frac- sider applying chemical fertilizer. Moreover, ture subsoil. See Summer Covers Relieve green manures sometimes continue to decom- Compaction (p. 84). pose after the cash crop no longer needs N.This One of the less appreciated soil benefits of N also is prone to leaching. cover crops is an increase in the total numbers To summarize, conventional plowing and and diversity of soil organisms.As discussed ear- aggressive disking can cause a rapid decomposi- lier, diversity is the key to a healthy, well-function of green manures, which could provide too tioning soil. Living covers help supply much N too soon in the cropping season. No-till year-round food for organisms that feed off root systems will have a reduced and more gradual by-products or that need the habitat provided on release of N, but some of that N may be vulnera- a residue-littered soil surface. Dead covers ble to gaseous loss, either by ammonia volatiliza- supply a more varied and increased soil diet for tion or by denitrification. Thus, depending on many organisms. management, soil and weather situations, N from Of course, unwanted pests may be lured to the legume cover crops may not be more efficiently field. Effective crop rotations that include cover used than N from fertilizer. crops, however, tend to reduce rather than Some possible solutions to this cover crop increase pest concerns. Pest-management consid- nitrogen-cycling dilemma: erations due to the presence of a cover crop are • A shallow incorporation of the green manure, discussed in the next chapter, Managing Pests as with a disk,may reduce the risk of gaseous loss. with Cover Crops (p. 25). • It may be feasible to no-till plant into the Finally, cover crops may have an added advan- green manure, then mow or incorporate it tage of drying out and therefore warming soils between the rows several weeks later, when cash during a cold, wet season.The flip side of this is crop roots are more developed and able to take that they may dry the soil out too much and rob up N. This has some risk, especially when soil the following crop of needed moisture. moisture is limiting, but can provide satisfactory There are no over-the-counter elixirs for renew- results if seedling survival is assured. ing soil. A long-term farm plan that includes • Residue from a grass/legume mix will have a cover crops, however, can help ensure your soil’s higher C:N than the legume alone, slowing the health and productivity for as long as you farm.

24 MANAGING COVER CROPS PROFITABLY MANAGING PESTS WITH COVER CROPS By Sharad C. Phatak

rop crops are poised to play increasingly productive for row crops and vegetables for the important roles on North American farms. first two to three years. High yields of agronomic CIn addition to slowing erosion, improving and horticultural crops are profitable, with soil structure and providing fertility, we are learn- comparatively few pesticide and fertilizer inputs. ing how cover crops help farmers to manage After that—under conventional systems with cus- pests. With limited tillage and careful attention tomary clean tillage—annual crops require higher to cultivar choice, placement and timing, cover inputs.The first several years of excessive tillage crops can reduce infestations by insects, diseases, destroys the food sources and micro-niches on nematodes and weeds. Pest-fighting cover crop which the soil organisms that help suppress pests systems help minimize reliance on pesticides,and depend. When protective natural biological as a result cut costs, reduce your chemical expo- systems are disrupted, pests have new openings sure, protect the environment, and increase con- and crops are much more at risk. sumer confidence in the food you produce. Cover crop farming is different from clean-field Farmers and researchers are using cover crops monocropping, where perfection is rows of corn to design new strategies that preserve a farm’s or cotton with no thought given to encouraging natural resources while remaining profitable. Key other organisms.Cover crops bring more forms of to this approach is to see a farm as an “agro- life into the picture and into your management ecosystem”—a dynamic relationship of the min- plan. By working with a more diverse range of eral, biological, weather and human resources crops,some growing at the same time in the same involved in producing crops or livestock.Our goal field, you’ve got a lot more options. Here’s a quick is to learn agricultural practices that are environ- overview of how these systems work. mentally sound,economically feasible and socially acceptable. Insect Management Environmentally sustainable pest management In balanced ecosystems, insect pests are kept in starts with building healthy soils. Research in check by their natural enemies. These natural south Georgia (see sidebar Georgia Cotton, pest controls—called beneficials in agricultural Peanut Farmers, p. 26) shows that crops grown systems—include predator and parasitoid insects on biologically active soils resist pest pressures and diseases. Predators kill and eat other insects; better than those grown on soils of low fertility, parasitoids spend their larval stage inside another extreme pH, low biological activity and poor soil insect, which then dies as the invader’s larval structure. stage ends. However, in conventional systems, There are many ways to increase biological synthetic chemical treatments that kill insect activity in soil. Adding more organic material by pests also typically kill their natural enemies. growing cover crops or applying manure helps. Conserving and encouraging beneficial organisms Reducing or eliminating pesticides favors diverse, is key to achieving sustainable pest management. healthy populations of beneficial soil flora and You should aim to combine strategies that make fauna. So does reducing or eliminating tillage that each farm field more hospitable to beneficials. causes losses of soil structure, biological life or Reduce pesticide use, and, when use is essential, organic matter. These losses make crops more select materials that are least harmful to beneficials. vulnerable to pest damage. Avoid or minimize cultural practices such as tilling Farming on newly cleared land shows the and burning that kill beneficials and destroy their process well. Land that has been in a “cover crop” habitat. Build up the sustenance and habitat that of trees or pastures for at least 10 years remains 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 already in place when you plant spring or sum- form of insects, pollen, honeydew and nectar. mer crops.However,if you fully incorporate cover By including cover crops in your rotations and crops, you destroy or disperse most of the benefi- not spraying insecticides, beneficials often are cials that were present. Conservation tillage is a

26 MANAGING COVER CROPS PROFITABLY The farmers get weed control by flail mowing • Weeds. Strip-tilling into over-wintered herbicide-killed, fall-planted rye, leaving about cover crops provides acceptable weed 6 inches of stubble. One or two post-emerge control for relay-cropped cucumbers (264). herbicide applications should suffice in the Conventional management of rye in our area first few years. I don’t recommend cultivation is usually to disk or kill it with broad- for weed control because it increases risks of spectrum herbicides such as paraquat or soil erosion and damages the protective outer glyphosate. leaf layer that helps prevent plant diseases. • Diseases. I’ve been strip-tilling crimson We see changes on farms where the clover since 1985 to raise tomatoes, peppers, rotations stay in place for three or more years: eggplant, cucumbers, cantaloupes, lima beans, • Insects. Insecticide costs are $50 snap beans, Southern peas and cabbages. I’m to $100/A less than conventional crop using no fungicides. Our research staff has management in the area for all kinds of raised peanuts no-tilled into cereal rye for the crops.The farmers using the alternative past six years, also without fungicides. system often substitute with insect control • Nematodes. If we start on land where materials such as Bacillus thuringiensis (Bt), pest nematodes are not a major problem, pyrethroids and insect growth regulators this system keeps them from becoming a that have less severe environmental impact. problem. These products are less persistent in the field Even though the conventional wisdom says environment, more targeted to specific pests you can’t build organic matter in our climate and do less harm to beneficials. By planting and soils, we have top-inch readings of 4 cover crops on field edges and in other non- percent organic matter in a field that tested crop areas, these farmers are increasing the 0.5 percent four years ago. numbers of beneficials in the field We are still learning, but know that we can environments. rotate crops, use cover crops and cut tillage Pests that are no longer a problem on the to greatly improve our sustainability.In our cover-cropped farms include thrips, bollworm, experience, we’ve reduced total costs by as budworm, aphids, fall armyworm, beet much as $200 per acre for purchased inputs armyworm and white flies. On my no-till and tillage. Parts of our system will work in research plots with cover crops and long many places. Experiment on a small scale to rotations, I’ve not used insecticides for six years look more closely at what’s really going in your on peanuts, for eight years on cotton and for 12 soil and on your crops. As you compare insights years on vegetables. I’m working with growers and share information with other growers and who use cover crops and crop rotations to researchers in your area, you’ll find cover crops economically produce cucumbers, squash, that help you control pests, too. peppers, eggplant, cabbage peanuts, soybeans —Sharad C. Phatak and cotton with only one or two applications of insecticide—sometimes with none.

better option because it leaves more of the cover Cover crops left on the surface may be living, crop residue on the surface. No-till planting only temporarily suppressed, dying or dead. In any disturbs an area 2 to 4 inches wide,while strip-till- event, their presence protects beneficials and ing disturbs an area up to about 24 inches wide their habitat. The farmer-helpful organisms are between undisturbed row middles. hungry, ready to eat the pests of cash crops that

MANAGING PESTS WITH COVER CROPS 27 are planted into the cover-crop residue. The The beneficial bugs destroyed all the beetles by ultimate goal is to provide year-round food and evening. habitat for beneficials to ensure their presence • Cucumber beetles seen attacking cucumber within or near primary crops. plants were similarly destroyed by beneficials We’re just beginning to understand the effects within a day. of cropping sequences and cover crops on bene- • Lady beetles in cover crop systems help to ficial and insect pest populations. Researchers control aphids attacking many crops. have found that generalist predators, which feed Properly selected and managed, cover crops on many species, may be an important biological can enhance the soil and field environment to control. During periods when pests are scarce or favor beneficials. Success depends on properly absent, several important generalist predators managing the cover crop species matched can subsist on nectar, pollen and alternative prey with the cash crops and anticipated pest threats. afforded by cover crops. This suggests you can While we don’t yet have prescription plantings enhance the biological control of pests by using guaranteed to bring in all the needed benefi- cover crops as habitat or food for the beneficials cials—and only beneficials—for long lists of cash in your area. crops, we know some associations : This strategy is important for farmers in the • We identified 13 known beneficial insects South, where pest pressure can be especially associated with cover crops during one growing heavy. In south Georgia, research showed that season in south Georgia vegetable plantings (34, populations of beneficial insects such as insidious 36, 39). flower bugs (Orius insidiosus), bigeyed bugs • In cotton fields in south Georgia where (Geocoris spp.) and various lady beetles residues are left on the surface and insecticides (Coleoptera coccinellidae) can attain high densi- are not applied, more than 120 species of benefi- ties in various vetches, clovers and certain crucif- cial arthropods, spiders and ants have been erous crops. These predators subsisted and observed. reproduced on nectar, pollen, thrips and aphids, • Fall-sown and spring-sown insectory mixes and were established before key pests arrived. with 10 to 20 different cover crops work well Research throughout Georgia, Alabama and under orchard systems. These covers provide Mississippi showed that when summer vegetables habitat and alternative food sources for beneficial 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. BUCKWHEAT grows quickly in cool, moist weather.

28 MANAGING COVER CROPS PROFITABLY insects. This approach has been used successfully minimize disease losses (259, 260, 331, 333, 334). by California almond and walnut growers partici- Now we realize that burying cover crop residues pating in the Biologically Intensive Orchard and disrupting the entire soil profile eliminates Systems (BIOS) project of the University of beneficial insect habitat and weed control bene- California (142). fits. The increased use of conservation tillage The level of ecological sustainability depends increases the need to manage crop disease with- on the grower’s interests, management skills and out burying cover crops. situation. Some use no insecticides while others Plant infection by microorganisms is rare (254). have substantially reduced insecticide applica- A pathogen has to cross many barriers before it tions on peanut, cotton and vegetable crops. can cause a disease to roots, stem or leaves.You • In Georgia, Mississippi and South Carolina, can use cover crops to reinforce two of these minimally tilled crimson clover or cahaba vetch barriers. before cotton planting have been successful in reducing fertilizer N up to 50 percent and insecti- Plant cuticle layer. This often waxy surface layer cide inputs by 30 to 100 percent. is the first physical barrier to plant infection. • Many farmers are adopting a system of trans- Many pathogens and all bacteria enter the plant planting tomatoes, peppers and eggplant into a through breaks, such as wounds, or natural open- killed hairy vetch or vetch/ ings, such as stomata, in this rye cover crop. Benefits Cover crops can enhance the cuticle layer. This protective include weed, insect and dis- layer can be physically dam- ease suppression, improved soil and field environment aged by cultivation, spraying fruit quality and overall lower to favor beneficial insects. and sand-blasting from wind production cost. erosion, as well as by the • Leaving “remnant impact and soil splashing strips” of a cover when most of the crop is from raindrops and overhead irrigation. In well- mowed or incorporated provides a continuing developed minimum-till or no-till crop systems refuge and food source for beneficials, which with cover crops, you may not need cultivation might otherwise leave the area or die. This for weed control (see below) and you can mini- method is used in orchards when continued mize spraying.Organic mulches from living,dying growth of cover crops would cause moisture or killed covers that hold soil and stop soil splash- competition with trees. ing protect crops from injury to the cuticle. • Insect movement is orchestrated in a system developed by Oklahoma State University for Plant surface microflora. Many benign organ- pecan growers. As legume mixtures senesce, isms are present on the leaf and stem surface. beneficials migrate into trees to help suppress They compete with pathogens for a limited sup- harmful insects. Not mowing the covers from ply of nutrients.Some of these organisms produce August 1 until shuck split of the developing natural antibiotics. Pesticides, soaps, surfactants, pecans lessens the unwanted movement of stink spreaders and sticking agents can kill or disrupt bugs, a pest which can damage green pecans the activities of these beneficial microorganisms, (209). In California, lygus bugs on berseem clover weakening the plant’s defenses. Cover crops can or alfalfa are pests of cash crops. Be careful that help this natural protection process work by cover crop maturity or killing a cover doesn’t reducing the need for synthetic crop protection force pests into a neighboring cash crop. materials. Further, cover crop plant surfaces can support healthy populations of beneficial Disease Management microorganisms, including types of yeasts, that Growers traditionally have been advised to turn can migrate onto a cash crop after planting or under plant debris by moldboard plowing to transplanting.

MANAGING PESTS WITH COVER CROPS 29 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 non- incarnatum)—Used as a self-reseeding winter host plant for root-knot nematodes and soil- annual legume throughout the Southeast, fall- 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 weed- suppresses weeds effectively by forming a suppressing compounds. thick mulch. Crimson supports high densities 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 soil- crimson clover can be managed to reseed in borne diseases, root-knot nematodes and late spring so that it resumes its growth in late broadleaf weeds in all cash crops that follow, summer and fall.

Soilborne pathogenic fungi limit production of In soils with high levels of disease inoculum, vegetables and cotton in the southern U.S. (332, however, it takes time to reduce population lev- 333, 334, 335). Rhizoctonia solani, Pythium els of soil pathogens using only cover crops. myriotylum, Pythium phanidermatum and After tests in Maine with oats, broccoli, white Pythium irregulare are the most virulent patho- lupine (Lupinus albus) and field peas (Pisum genic fungi that cause damping-off on cucumbers sativum) as covers,researchers cautioned it may and snap beans. Sclerotium rolfsii causes rot in take three to five years to effectively reduce all vegetables and in peanuts and cotton. Infected stem lesion losses on potatoes caused by R. plants that do not die may be stunted because of solani (190).Yet there are single-season improve- lesions caused by fungi on primary or secondary ments, too. For example, in an Idaho study, roots,hypocotyls and stems.But after two or three Verticillium wilt of potato was reduced by 24 to years in cover cropped, no-till systems, damping- 29 percent following Sudangrass green manure. off is not a serious problem, experience on south Yield of U.S.No.1 potatoes increased by 24 to 38 Georgia farms and research plots shows. Higher percent compared with potatoes following soil organic matter may help. barley or fallow (322).

30 MANAGING COVER CROPS PROFITABLY • Subterranean Clover (Trifolium no-till system substantially reduces root-knot subterraneum)—A self-reseeding annual nematodes, soil-borne diseases and broadleaf legume, fall-planted subterranean clover carries weeds. By using clovers and vetches in your the same risks as crimson clover with soil- fields and adding beneficial habitat in non- borne diseases and nematodes. It suppresses cultivated areas, you can increase populations weeds more effectively in the deep South, of beneficial insects that help to keep insects however, because of its thick and low growth pests under control. Mixed plantings of a small habit. Subclover supports a high level of grains and legumes combine benefits of both beneficial insects. while reducing their shortcomings. • Cahaba White Vetch (V.sativa X V. As pesticides of all types (fungicides, cordata)—This cool-season annual legume is a herbicides, nematicides and insecticides) are hybrid vetch that increases soilborne diseases reduced, the field environment becomes yet suppresses root-knot nematodes. It increasingly resilient in keeping pest outbreaks supports beneficial insects, yet attracts very in check. Plantings to further increase high numbers of the tarnished plant bug, a beneficial habitat in non-cultivated areas can serious pest. help maintain pollinating insects and pest • Buckwheat (Fagopyrum esculentum)— predators, but should be monitored to avoid A summer annual non-legume, buckwheat is build-ups of potential pests. Researchers are very effective in suppressing weeds when only beginning to understand how to manage planted thickly.It also supports high densities these “insectary plantings.” of beneficial insects. It is suitable for sequential Editor’s Note: Each cover crop listed here, planting around non-crop areas to provide except for cahaba vetch, is included in the food and habitat for beneficial insects. It is charts (pp. 48 and following) and is fully very attractive to honeybees. described in its respective section. Check the A well-planned crop rotation maximizes Table of Contents (p. 6) for location. benefits and compensates for the risks of —Sharad C. Phatak cover crops and cash crops. Planting rye in a

Nematode Management This coexistence would be the case in the undis- Nematodes are minute roundworms that interact turbed field or woodland described above. directly and indirectly with plants. Some species In conventional crop systems, pest nematodes feed on roots and weaker plants, and also intro- have abundant food and little environmental resis- duce disease through feeding wounds. Most tance. This can lead to rapid expansion of plant nematodes are not plant parasites,but feed on and parasitic species, plant disease and yield loss. interact with many soil-borne microorganisms, Cropping systems that increase biological diversi- including fungi, bacteria and protozoa. Damage ty over time usually prevent the onset of from plant-parasitic nematodes results in a break- nematode problems. Reasons may include a down of plant tissue, such as lesions or yellow dynamic soil ecological balance and improved, foliage; retarded growth of cells, seen as stunted healthier soil structure with higher organic growth or shoots; or excessive growth such as matter. In Michigan, some potato growers report root galls, swollen root tips or unnatural root that two years of alfalfa to limit nematodes branching. between potato crops is sustainable for them If the community of nematodes contains because of improvements to potato production diverse species, no single species will dominate. and lower pest control costs (20).

MANAGING PESTS WITH COVER CROPS 31 Once a nematode species is established in a better than if the cover was buried more deeply field, it is usually impossible to eliminate it. Some by moldboard plowing. Associated greenhouse covers can enhance a resident parasitic nematode tests in the study showed that incorporated rye population if they are grown before or after was effective against root-knot,reniform and stub- another crop that hosts a plant-damaging nema- by root nematodes, as well (14). tode species. Malt barley, corn, radishes and mustard some- If a nematode pest species is absent from the times worked as well as the standard nematicide soil, planting a susceptible cover crop will not to control sugar beet nematode in Wyoming sugar give rise to a problem,assuming the species is not beets,a 1994 study showed.Increased production introduced on seed, transplants or machinery more than offset the cover crop cost, and lamb (296). One Iowa farmer reports that researchers grazing of the brassicas increased profit without analyzing his fields have found no evidence that diminishing nematode suppression. The success hairy vetch,a host for soybean cyst nematode,has is conditional upon a limited nematode density. caused any problem with the pest in his soy- The cover crop treatment was effective only if beans. This may be due to his use compost in there were fewer than 10 eggs or juveniles per strip-cropped fields with an oats/hairy cubic centimeter of soil. A moderate sugar beet vetch>corn>soybean rotation (346). nematode level was reduced 54 to 75 percent in You can gradually reduce a field’s nematode about 11 weeks, increasing yield by nearly 4 tons pest population or limit nematode impact on per acre (184). crops by using specific cover crops. Nematode control tactics involving covers include: Weed Management • Manipulating soil structure or soil humus Cover crops are widely used as smother crops to • Rotating with non-host crops shade and out-compete weeds. Cereal grains • Using crops with nematicidal effects, such as establish quickly as they use up the moisture, fer- brassicas tility and light that weeds need to survive. Cover crops may also improve overall plant Sorghum-sudangrass hybrids and buckwheat are vitality to lessen the nematode impact on yield. warm-season crops that suppress weeds through But if you suspect nematode trouble, send a soil these physical means and by plant-produced sample for laboratory analysis to positively identi- natural herbicides (allelopathy). fy the nematode species.Then be sure any cover Cereal rye is an overwintering crop that sup- crops you try aren’t alternate hosts for that pest presses weeds both physically and chemically. If species. Area IPM specialists can help you. rye residue is left on the soil surface, it releases Using brassicas and many grasses as cover allelochemicals that inhibit seedling growth of crops can help you manage nematodes. Cover many annual small-seeded broadleaf weeds, such crops with documented nematicidal properties as pigweed and lambsquarters. The response of against at least one nematode species include grassy weeds is more variable.Rye is a major com- sorghum-sudangrass hybrids (Sorghum bicolor X ponent in the killed organic mulches used in no- S. bicolor var. sudanese), marigold (Tagetes till vegetable transplanting systems. patula), hairy indigo (Indigofera hirsuta), showy Killed cover crop mulches last longer if the crotalaria (Crotolaria spectabilis), sunn hemp stalks are left intact, providing weed control well (Crotalaria juncea) and velvetbean (Mucuna into the season for summer vegetables. Two deeringiana). implements have been modified in recent years You must match specific cover crop species specifically to enhance weed suppression by with the particular nematode pest species, then cover crops. The undercutter uses a wide blade manage it correctly. For example, cereal rye to slice just under the surface of raised beds, sev- residue left on the surface or incorporated to a ering cover crop plants from their root mass.An depth of several inches suppressed Columbia attached rolling harrow increases effectiveness lance nematodes in North Carolina cotton fields (69, 70, 71, 72). A Buffalo rolling stalk chopper

32 MANAGING COVER CROPS PROFITABLY 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 mid- bloom 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 Cover crops often suppress weeds early, then support field traffic. prevent erosion or supply fertility later in the sea- To avoid competition with the cash crop,living son. For example, shade-tolerant legumes such as mulches can be chemically or mechanically red clover or sweetclover that are planted with suppressed. In the Southeast, some cool-season spring grains grow rapidly after grain harvest to cover crops such as crimson clover die out natu- prevent weeds from dominating fields in late sum- rally during summer crop growth and do not mer. Overseeding annual ryegrass or oats at soy- compete for water or nutrients. However, cover bean leaf yellowing provides a weed-suppressing crops that regrow during spring and summer— cover crop before frost and a light mulch to sup- such as subterranean clover, white clover and red press winter annuals, as well. clover—can compete strongly for water with Cover crops can play a pest-suppressing role spring-planted crops unless the covers are ade- on virtually any farm. As we find out more about quately suppressed. the pest management benefits of cover crop sys- In New York, growing cover crops overseeded tems, they will become even more attractive within three weeks of potato planting provided from both an economic and an environmental good weed suppression, using 70 percent less perspective. Traditional research will identify herbicide. Yield was the same as, or moderately some new pieces of these biologically based reduced from, the standard herbicide control systems. However,growers who understand how plots in the two-year study.Hairy vetch,woolypod all the elements of their farm fit together will vetch, oats, barley, red clover and an oats/hairy be the people who will really bring cover crops vetch mix were suppressed as needed with fluaz- into the prominence they deserve in sustainable ifop and metribuzin (280). farming.

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

MANAGING PESTS WITH COVER CROPS 33 CROP ROTATION WITH COVER CROPS

Readers’ note: > indicates progression to may be the ideal window for establishing a cover another crop; / indicates a mixture of crops crop. Consider using an early-maturing cash crop growing at the same time. to allow for timely planting of the cover crop.The ideas in this book will help you see cover crop ne of the biggest challenges of cover opportunities in what used to look like problems. cropping is to fit cover crops into your Ocurrent rotations, or to develop new COVER CROPS FOR CORN BELT GRAIN rotations that take full advantage of their benefits. AND OILSEED PRODUCTION This section will explore some of the systems used successfully by farmers in different regions In addition to providing winter cover and build- of the U.S. One might be easily adapted to fit your ing soil structure, nitrogen (N) management will existing crops, equipment and management. probably be a major factor in your cover crop Other examples may point out ways that you can decisions for the corn>soybean rotation. A fall- modify your rotation to make the addition of planted grass or small grain will scavenge leftover cover crops more profitable and practical. N from the previous corn or soybean crop. Whether you add covers to your existing rota- Legumes are much less efficient at scavenging N, tions or totally revamp your farming system, it is but will add N to the system for the following crucial that you devote as much planning and crop. Legume/grass mixtures are quite good at attention to your cover crops as you do to your both. cash crops. Failure to do so can lead to failure of the cover crop and cause problems in other parts Corn>Soybean Systems of your system. Also remember that there is likely Keep in mind that: corn is a heavy nitrogen feed- no single cover crop that is right for your farm. er; soybeans benefit little, if at all, from cover crop Ultimately, rotating cover crops might be your N; and that you have a shorter time for spring best strategy. (See, for example, California legume growth before corn than before soybeans. Vegetable Crop Systems, p. 37). Like any other crop, pest pressures may build up if a cover crop Cover crop features: rye provides winter cover, is grown too often in the same field. scavenges N after corn, becomes a long-lasting (6- Before you start: week) residue for your beans to suppress weeds •Review Benefits Of Cover Crops (p. 9) and and hold moisture; hairy vetch provides spring Selecting the Best Cover Crops For Your Farm ground cover,abundant N and a moderate-term (3 (p. 12) to 4 week) mulch for the next corn crop; field • Decide which benefits are most important peas are similar to vetch, but residue breaks to you down faster; red clover is also similar, but pro- • Read the examples below,then consider how duces slightly less N and has less vigorous spring these cover crop rotations might be adapted regrowth; berseem clover grows quickly to pro- to your particular conditions vide several cuttings for high-N green manure, • Talk to your neighbors and the other “experts” then winterkills. in your area, including the contact people list- Here are some options to consider adapting to ed in Regional Experts (p. 173) your system: • Start small on an easily accessible plot that you will see often Corn>Rye>Soybeans>Hairy Vetch. In Zone 7 Be an opportunist—and an optimist. If your and warmer, you can grow a cover crop every cropping plans for a field are disrupted by weath- year between your corn and full-season beans. er or other conditions outside of your control,this Also, you can use wheat or another small grain to

34 MANAGING COVER CROPS PROFITABLY replace the cover crop before beans, in a three- Worried about soil moisture? There’s no crop, two-year rotation (corn>wheat>doublecrop question that growing cover crops may consume beans). In all cases, another legume or a soil moisture needed by the next crop. In humid grass/legume mixture can be used instead of a sin- regions, this is a problem only in an unusually dry gle species cover crop. Where it is adapted, you spring.Time permitting, allow 2 to 3 weeks after can use crimson clover or a crimson/grass mix- killing the cover crop to alleviate this problem. ture instead of vetch. While spring rainfall may compensate for the In cooler areas, plant rye as soon as possible moisture demand of most cover crops by normal after corn harvest. If you need more time in the planting dates, rye can quickly dry out a field. fall, try overseeding in rowed beans at drydown Later in the season, killed cover crop residues “yellow leaf”stage in early fall, or in early summer in minimum tillage systems can conserve at the last cultivation of corn. Seeding options moisture and increase yields. include aerial application where the service is In dryland areas of the Southern Great Plains, economical, using a specialty high-body tractor lack of water limits cover crop use. (See Dryland with narrow tires,or attaching a broadcast seeder, Cereal Cropping Systems, p. 40). air seeder or seed boxes to a In any system where you cultivator. Growers are looking to add are using accumulated soil Kill the rye once it is about moisture to grow your cash knee-high, or let it go a bit a small grain to their crop, you need to be extra longer, killing it a couple of corn>soybean rotation. careful. However,as noted in weeks before planting beans. this section and elsewhere Killing the rye with herbi- in the book, farmers and cides and no-tilling beans in narrow rows allows researchers are finding that water-thrifty cover more time for cover crop growth, since you don’t crops may be able to replace even a fallow year have to work the ground. If soil moisture is low, without adversely affecting the cash crop. consider killing the rye earlier. Follow the beans with hairy vetch or a vetch/small grain mixture. Corn>Rye>Soybeans>Small Grain>Hairy Legumes must be seeded at least 6 weeks before Vetch. This rotation is similar to the hard frost to ensure winter survival. Seed by corn>rye>soybeans rotation described above, drilling after soybean harvest, or by overseeding except you add a year of small grains following before leaf drop. Allow the vetch (or mixture) to the beans. This is the standard rotation in the grow as long as possible in spring for maximum N grain-growing regions of Paraguay and Brazil, fixation. where it is critical to maintain soil organic matter. Worried about planting your corn a bit In crop rotation research from different areas, late because you’re waiting for your cover crop to many benefits accrue as the rotation becomes mature? Research in Maryland, Illinois and else- longer. This is because weed, disease and insect where suggests that planting corn towards the pest problems generally decrease with an end of the usual window when using a legume increase in years between repeat plantings of the cover crop has its rewards. The delay can result same crop. in greater yields than earlier planting, due to Residue from small grains provides good organ- greater moisture conservation and more N pro- ic matter for soil building, and in the case of win- duced by the cover crop, or due to the timing of ter grains, the plants help to prevent erosion over summer drought (62, 64, 243, 338). Check your winter after soybeans loosen up the soil. If seed- state variety trial data for a shorter season corn ing with small grains, select cover crops that will hybrid that yields nearly as well as slightly longer stand shade and some traffic. season corn.The cover crop benefit should over- The length of the growing season will deter- come many yield differences. mine how you fit in cover crops after full-season

CROP ROTATION WITH COVER CROPS 35 soybeans in the rotation. Consider using a short- or oats for grain, frost-seed red clover or sweet- season bean if needed in order to achieve timely clover in March, harvest the grain, then let the planting after soybean harvest.Calculate whether clover grow until it goes dormant in late fall. cover crop benefits will compensate for a possi- Follow with corn the next spring. Some sec- ble yield loss on the shorter season beans.If there ondary tillage can be done in the fall,if conditions is not enough time to seed a legume after har- allow.One option is to attach sweeps to your chis- vest, use a small grain rather than no cover crop el plow and run them about 2 inches deep, cut- at all. ting the clover crowns (326). The small grain scavenges leftover N following Alternatively, grow the small grain to maturity, beans. Legume cover crops reduce fertilizer N harvest, then immediately plant a legume cover needed for following corn, a heavy N feeder. If crop such as hairy vetch or red clover in August or you cannot seed the legume at least six weeks early September. Soil moisture is critical for quick before a hard frost, consider overseeding before germination and good growth before frost. For leaf drop or at last cultivation. much of the northern U.S., there is not time to An alternate rotation for the lower mid-South plant a legume after soybean harvest,unless it can is corn>crimson clover (allowed to go to seed) be seeded aerially or at the last cultivation. If > soybeans > crimson clover (reseeded) > corn. growing spring grains, seed red clover or sweet- Allow the crimson clover to go to seed before clover directly with the small grain. planting beans. The clover germinates in late sum- Adding the small grain to the rotation helps mer under the beans. Kill the cover crop before control white mold on soybeans, since two years corn the next spring. If possible, choose a differ- out of beans are needed to reduce pathogen pop- ent cover crop following the corn this time to ulations. Using a grain/legume mix will scavenge avoid potential pest and disease problems with available N from the bean crop, hold soil over the crimson clover. winter and begin fixing N for the corn. Clovers or vetch can be harvested for seed,and red or yellow Precaution. In selecting a cover crop to clover can be left for the second year as a green interseed, do not jeopardize your cash crop if soil manure crop. moisture is usually limiting during the rest of the Using a spring seeding of oats and berseem corn season! Banding cover crop seed in row clover has proved effective on Iowa farms that middles by using insecticide boxes or other also have livestock. The mix tends to favor oat devices can reduce cover crop competition with grain production in dry years and berseem pro- the cash crop. duction in wetter years. Either way the mixture provides biomass to increase organic matter and 3 Year: Corn>Soybean>Wheat/Red Clover. build soil. The berseem can be clipped several This well-tested Wisconsin sequence provides N times for green manure. for corn as well as general rotation effects in weed suppression and natural controls of disease and Precaution. Planting hairy vetch with small insect pests. It was more profitable in recent grains may make it difficult to harvest a clean years as the cost of synthetic N increased. Corn grain crop. Instead, seed vetch after small grain benefits from legume-fixed N, and from the harvest. improved cation exchange capacity in the soil that comes with increasing organic matter levels. COVER CROPS FOR VEGETABLE PRODUCTION With the changes in base acreage requirements in the 1996 Farm Bill, growers in the upper Vegetable systems often have many windows for Midwest are looking to add a small grain to their including cover crops. Periods of one to two corn>bean rotation.The small grain, seeded after months between harvest of early planted spring soybeans,can be used as a cover crop,or it can be crops and planting of fall crops can be filled grown to maturity for grain.When growing wheat using fast-growing warm-season cover crops such

36 MANAGING COVER CROPS PROFITABLY as buckwheat, cowpeas, sorghum-sudangrass Some farmers maximize the complementary hybrid, or another crop adapted to your condi- weed-suppressing effects of various cover crop tions. As with other cropping systems, plant a species by orchestrating peak growth periods, winter annual cover crop on fields that otherwise rooting depth and shape, topgrowth differences would lie fallow. and species mixes. See Full-Year Covers Tackle Where moisture is sufficient, many vegetable Tough Weeds (p. 38). crops can be overseeded with a cover crop, which will then be established and growing after vegetable 3 Year: Winter Wheat/Legume Interseed> harvest. Select cover crops that tolerate shade and Legume>Potatoes. This eastern Idaho rotation harvest traffic, especially where there will be multi- conditions soil, helps fight soil disease and ple pickings, such as in tomatoes or peppers. provides N. Sufficient N for standard potatoes depends on rainfall being average or lower to Cover crop features: Oats add lots of biomass, prevent leaching that would put the soil N below are a good nurse crop for spring-seeded legumes, the shallow-rooted cash crop. and winterkill, doing away with the need for spring killing and tilling. Sorghum-sudangrass 1 Year: Lettuce>Buckwheat>Buckwheat> hybrid produces deep roots and tall, leafy stalks Broccoli>White Clover/Annual Ryegrass.The that die with the first frost. Yellow sweetclover Northeast’s early spring vegetable crops often is a deep rooting legume that provides cuttings of leave little residue after their early summer har- green manure in its second year. White clover is vest. Sequential buckwheat plantings suppress a persistent perennial and weeds, loosen topsoil and good N source. Residue from small grains attract beneficial insects. In Zone 5 and cooler, Buckwheat is easy to kill by plant rye, oats or a summer provides organic matter for mowing in preparation for fall annual (in August) after snap soil building. . . to prevent transplants. With light tillage bean or sweet corn harvest to incorporate the relatively for organic matter produc- erosion over winter. small amount of fast-degrad- tion and erosion control, ing buckwheat residue, you especially on sandy soils. Incorporate the follow- can then sow a winter grass/legume cover mix to ing spring, or leave untilled strips for continued hold soil throughout the fall and over winter. control of wind erosion. Planted at least 40 days before frost, the white If you have the option of a full year of cover clover should overwinter and provide green crops in the East or Midwest, plant hairy vetch in manure or a living mulch the next year. the spring, allow to grow all year, and it will die back in the fall. Come back with no-till sweet or California Vegetable Crop Systems field corn or another N-demanding crop the Innovative work in California includes rotating following spring. Or, hairy vetch planted after cover crops as well as cash crops, adding diversi- about August 1 will overwinter in most zones ty to the system.This was done in response to an with adequate snow coverage. Allow it to grow increase in Alternaria blight in LANA vetch if until early flower the following spring to achieve planted year after year. full N value. Kill for use as an organic mulch for no-till transplants or incorporate and plant a 4 Year: LANA Vetch>Corn>Oats/Vetch>Dry summer crop. Beans>Common Vetch>Tomatoes>S-S Hybrid/ You can sow annual ryegrass right after har- Cowpea>Safflower. The N needs of the cash vesting an early-spring vegetable crop, allow it to crops of sweet corn,dry beans,safflower and can- grow for a month or two, then kill, incorporate ning tomatoes determine,in part,which covers to and plant a fall vegetable. grow. Corn, with the highest N demand, is pre-

CROP ROTATION WITH COVER CROPS 37 Full-Year Covers Tackle Tough Weeds TROUT RUN, Pa.—Growing cover crops for a a week or two after planting but before leaves full year between cash crops helps Eric and open up to trap sweetclover seeds, while Anne Nordell control virtually every type of onions are overseeded near harvest.The weed nature throws at their vegetable farm— Nordells walk up and down every other row even quackgrass. with a manual Cyclone seeder (canvas bag The couple experimented with many with a hand-crank spinner).They harvest the different cover crops on their north-central cash crop, then let the clover grow through Pennsylvania farm before adapting a system summer. used to successfully battle quackgrass Yellow blossom sweetclover—one of the on a commercial herb farm in the Pacific best cover crop choices for warm-season Northwest. Between cash crops, the Nordells nitrogen production—puts down a deep grow two winter cover crops to smother taproot before winter if seeded in June or weeds.A brief stint of aggressive summer July,observes Eric.“That root system loosens tillage between the two cover crops keeps the soil, fixes nitrogen, and may even bring annual weeds from setting seed. up minerals from the subsoil with its long Regular use of cover crops in their half- tap root.”He points out that the clover alone acre strips between rows of vegetables also would not suppress weeds.The sole-seeding improves soil quality and moisture retention works on their farm because of their while reducing erosion.“Vegetable crops successful management efforts over a return very little to the soil as far as a root decade to suppress overall weed pressure system,”says Eric, a frequent speaker on by crop rotation and varied cover crops. conservation practices at conferences in the In spring, the sweetclover grows until it Northeast.“You cut a head of lettuce and have is about knee-high in mid-May. Then the nothing left behind. Growing vegetables, we’re Nordells clip it just before it buds.They let always trying to rebuild the soil.” the regrowth bloom to attract pollinators The Nordells’ short growing season— and beneficial insects to the field, before which typically ends with the first frost in clipping it again in July. September—makes it challenging to squeeze In early- to mid-July,the Nordells moldboard in cover crops on their six cultivated acres. plow the sweetclover to kill it.They leave the Yellow blossom sweetclover is overseeded ground in bare fallow,working it again with a at 20 to 24 lb./A into early crops such as springtooth harrow to hit perennial weeds at onions or spring lettuce. Lettuce is overseeded the weakest point of their lifecycle. After that,

ceded by LANA vetch, which produces more N than of the N required by the subsequent tomato crop, other covers. Before tomatoes, common vetch works with about 30 to 40 lb. N/A added as starter. best. A mixture of purple vetch and oats is grown A mixture of sorghum-sudangrass and cowpeas is before dry beans, and a mix of sorghum-sudangrass planted following tomato harvest. The mixture and cowpeas precedes safflower. responds to residual N levels with N-scavenging by In order to get maximum biomass and N the grass component to prevent winter leaching. production by April 1,LANA vetch is best planted early The cowpeas fix enough N for early growth of the enough (6 to 8 weeks before frost) to have good subsequent safflower cash crop, which has relative- growth before “winter.”Disked in early April,LANA pro- ly low initial N demands. The cover crop breaks vides all but about 40 lb.N/A to the sweet corn crop. down fast enough to supply safflower’s later-season Common vetch, seeded after the corn, can fix most N demand.

38 MANAGING COVER CROPS PROFITABLY the couple harrows every two to three weeks The Nordells plow the rye/vetch mix to bring weed roots and rhizomes to the soil after it greens up in late March to early April, surface, where they bake in the summer sun. working shallowly so as not to turn up as The harrowing also kills flushes of annual many weed seeds.They forego maximum weeds before they can set seed. biomass and N for earlier planting of their After five years in this weed-killing cash crop—tomatoes, peppers, summer rotation, the Nordells were able to cut back broccoli or leeks—around the end of May. on harrowing, which they now coordinate The bare fallow during mid-summer plus with rainfall and weed pressure. In the early spring incorporation of overwintering unusually dry summer of 1997, for example, cover crops are the best preventive to slugs they did not harrow at all after plowing. and grubs, they have found. In mid-August, the Nordells plant a second, Thanks to their weed-suppressing cover overwintering cover crop. In this rotation, crops, the Nordells typically spend less than they seed a mix of rye and hairy vetch.They 10 hours a season hand-weeding their three broadcast and lightly incorporate about 80 acres of cash crops, and never need to hire pounds rye and 30 pounds vetch per acre. outside weeding help.“Don’t overlook the The rye establishes quickly,putting on good cover crops’ role in improving soil tilth and growth both above and below the surface, making cultivation easier,”adds Eric. Before while the vetch fixes nitrogen.Another cover cropping, he noticed that their silty combination is yellow,red and white clover in soils deteriorated whenever they grew two a 2:2:1 ratio by volume.“We’re looking for a cash crops in a row.“When the soil structure green field by Labor Day,”Eric says.“We want declines, it doesn’t hold moisture and we a good sod before we get our first freeze.” get a buildup of annual weeds,”he notes. Rye and vetch are a popular combination The Nordells can afford to forego a cash to manage nitrogen.The rye takes up excess crop to keep half their land in cover crops N from the soil, preventing leaching.The because their tax bills and land value are not vetch fixes additional nitrogen which it as high as market gardeners in a more urban releases after it’s killed the following spring setting.“We take some land out of production, prior to planting the next cash crop. but in our situation, we have the land,”Eric With the August seeding, the Nordells’ says.“If we had to hire people for weed rye/vetch mixture produces most of its control, it would be more costly.” biomass in fall. See Recommended Resources (p. 162) to order a video describing this system.

Precaution. If you are not using any herbi- maintain soil productivity, and provide the many cides, vetch could become a problem in the other benefits of cover crops highlighted California system.Earlier kill sacrifices N,but does throughout this book. not allow for the production of hard seed that Hairy vetch, crimson clover, or mixtures with stays viable for several seasons. rye or another small grain can reduce erosion,add N and organic matter to the system. Drill after COVER CROPS FOR COTTON PRODUCTION shredding stalks in the fall and kill by spraying or mowing prior to no-till seeding of cotton in May. In what would otherwise be continuous cotton Or, aerially seed just before application of production, any winter annual cover crop added defoliant. The dropping leaves mulch the cover to the system can add rotation benefits, help crop seed, aiding germination. Rye works better

CROP ROTATION WITH COVER CROPS 39 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 attach- ments to clear residue. Band-spray normal pre- emergent 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 Precautions clover and some crimson clover cultivars set seed • Watch for moisture depletion if spring is quickly enough in some areas to become perpet- unusually dry. ually reseeding when cotton planting dates are • Be sure to plant cotton by soil temperature late enough in spring.Germination of hard seed in (65 F is required), because cover crops may late summer provides soil erosion protection over keep soil cool in the spring. Don’t plant too winter, N for the following crop and an organic early! mulch at planting. • A delay of two to three weeks between cover Strip planting into reseeding legumes works for crop kill and cotton planting reduces these many crops in the South, including cotton, corn, problems, and reduces the chance of stand sweet potatoes, peanuts, peppers, cucumbers, losses due to insects (cutworm), diseases or cabbage and snap beans. Tillage or herbicides allelopathic chemicals. are used to create strips 12 to 30 inches wide. • Additional mid-summer weed protection is Wider killed strips reduce moisture competition needed during the hot-season “down time” for by the cover crop before it dies back naturally,but the reseeding legumes. also reduce the amount of seed set, biomass and N produced. Wider strips also decrease the DRYLAND CEREAL-LEGUME mulching effect from the cover crop residue. CROPPING SYSTEMS The remaining strips of living cover crop act as in-field insectary areas to increase overall insect Soil moisture availability and use by cover crops populations, resulting in more beneficial insects are the dominant concerns in dryland production to control pest insects. 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.

40 MANAGING COVER CROPS PROFITABLY Start Where You Are In many instances, you can begin using cover spring cover crop killing, try a non-hardy cultivar crops without substantially altering your cash of berseem clover or annual alfalfa. crop mix or planting times or buying new If you have livestock, a forage/hay market machinery.Later, you might want to change option or want more soil benefits, choose a your rotation or other practices to take better longer-lived legume cover. advantage of cover crop benefits. We’ll use a basic Corn Belt situation as a Corn>Soybean>Small Grain/Legume> model. From a corn>soybean rotation, you Legume Hay, Pasture Or Green Manure. can expand to: Yellow sweetclover or red clover are popular forage choices. An oats/berseem interseeding Corn>Cover>Soybean>Cover. Most popular provides a forage option the first year. choices are rye or rye/vetch mixture following Harvesting the cover crop or incorporating corn; vetch or rye/vetch mixture following it early in its second season opens up new beans. Broadcast or drill covers immediately options for cash crops or a second cover crop. after harvest. Hairy vetch needs at least 15 Late-season tomatoes, peppers, vine crops days before frost in 60 F soil. Rye will germi- or sweet corn all thrive in the warm, enriched nate as long as soil is just above freezing. Drill soil following a green manure. Two heat-loving for quicker germination. Consider overseeding covers that could be planted after killing a cool- at leaf-yellowing if your post-harvest planting season legume green manure are buckwheat window is too short. (used to smother weeds, attract beneficial If you want to make certain the legume is insects or for grain harvest) and sorghum- well established for maximum spring N and Sudangrass hybrid (for quick plow-down biomass production, consider adding a small biomass or to fracture compacted subsoil). grain to your rotation. These crops would work most places in the Corn Belt. To get started in your area, check Corn>Soybean>Small Grain/Cover. Small Top Regional Cover Crop Species (p. 47) grains could be oats, wheat or barley.Cover to fill various roles, or Cultural Traits and could be vetch, field peas or red clover. If you Planting (p. 50) to find which cover crops want the legume to winterkill to eliminate fit best in your system.

ing that carefully managed and selected cover Systems: Nine Farm Case Studies in the Dryland crops in their rotations result in increased soil Northern Plains, Canadian Prairies and moisture availability to their cash crops.This deli- Intermountain Northwest. See Appendix C, cate balance between water use by the cover Recommended Resources (p. 163). crop and water conservation will dictate, in part, In an area of Montana receiving 11 to 12 inch- how cover crops work in your rotation. es of rainfall per year,where summer fallow is the norm, some farmers and ranchers are using cover Cover crop features: perennial medics per- crops and longer rotations to eliminate fallow. sist due to hard seed,providing green manure and Greg Gould believes he can do without summer erosion control; field peas and lentils (grain fallow because his rotation has improved his soil’s legumes) are shallow-rooted yet produce crops water-holding capacity. While most farmers in his and additional N in years of good rainfall. area think water is the limiting factor, he thinks it An excellent resource describing these rota- is the condition of the soil. tions in detail is Cereal-Legume Cropping

CROP ROTATION WITH COVER CROPS 41 7 to 13 Years: Flax>Winter Wheat>Spring clover, which can leave topsoil fairly dry. Spring- Barley>Buckwheat>Spring Wheat>Winter seeded grains prevent weeds that show up with Wheat>Alfalfa (up to 6 years) >Fallow successive winter grain cycles and have shallower System sequences are: roots that allow soil moisture to build up deeper • Flax or other spring crops (buckwheat, wheat, in the profile. barley) are followed by fall-seeded wheat In the second spring-grain year, using a low-N (sometimes rye), harvested in July,leaving demanding crop such as kamut wheat reduces stubble over the winter; the risk of N-deficiency. Sweetclover seeded with • Spring-seeded barley or oats, harvested in the kamut provides regrowth the next spring that August, leaving stubble over the winter; helps to take up enough soil water to prevent • Buckwheat, seeded in June and harvested in saline seep. Black medic, INDIANHEAD lentils and October, helps to control the weeds that have SIRIUS field peas are water-efficient substitutes for begun cropping up; the deep-rooted—and water hungry—alfalfa and • A spring small grain, which outcompetes any sweetclover. These peas and lentils are spring- volunteer buckwheat (alternately,fall-seeded sown, providing back-up N production if the for- wheat, or fall-seeded sweetclover for seed or age legumes fail to establish. hay). While moisture levels fluctuate critically from The rotation closes with up to 6 years of alfalfa, year to year in dryland systems,N levels tend to be plowdown of sweetclover seeded with the previ- more stable than in the hot, humid South, and ous year’s wheat or an annual legume green adding crop residue builds up soil organic matter manure such as Austrian winter peas or berseem more easily. Low-water use cover crops have clover. been shown to use equal or less soil water than There are many points during this rotation where bare fallow treatment, while adding organic mat- a different cash crop or cover crop can be substitut- ter and N. Consequently, dryland rotations can ed, particularly in response to market conditions. have a significant impact on soils and the field Furthermore, with Angus cattle on the ranch, many environment when used over a number of years. of the crops can be grazed or cut for hay. When starting with dryland soil that has raised Moving into areas with more than 12 inches of the same crop for many years with conventional rain a year opens additional windows for incor- inputs, it will take three to five years of soil-build- porating cover crops into dryland systems. ing rotations until soils become biologically active. This is the length of time often cited by 9 Year: Winter Wheat>Spring Wheat>Spring farmers in many regions for soil-based changes to Grain/Legume Interseed>Legume Green take place. These improved soils have higher Manure/Fallow>Winter Wheat>Spring organic matter, a crumbly structure, and good Wheat>Grain/Legume Interseed>Legume> water retention and infiltration. They also resist Legume. In this rotation, one year of winter compaction and effectively cycle nutrients from wheat and two years of spring-seeded crops fol- residue to following crops. low a two or three-year legume break. Each Remember, the benefits of cover crops accrue legume sequence ends with an early summer over several years.You will see improvements in incorporation of the legume to save moisture fol- crop yield, pest management and soil tilth if you lowed by minimal surface tillage to control commit to cover crop use whenever and wherev- weeds. Deep-rooted winter wheat follows sweet- er possible in your rotations.

42 MANAGING COVER CROPS PROFITABLY INTRODUCTION TO CHARTS

he four comprehensive charts that follow crop is included in the “Weed Fighter” ratings for can help orient you to the major cover legumes usually planted with a grain or grass T crops most appropriate to your needs and nurse crop. region.Bear in mind that choice of cultivar,weather extremes and other factors may affect a cover Column headings crop’s performance in a given year. Legume N Source. Rates legume cover crops for CHART 1: TOP REGIONAL COVER CROP their relative ability to supply fixed N. SPECIES (Nonlegumes have not been rated for their biomass nitrogen content,so this column is left blank This chart lists up to five cover crop recommen- for nonlegumes.) dations per broad bioregion for six different major purposes: N Source, Soil Builder, Erosion Total N. A quantitative estimate of the reason- Fighter, Subsoil Loosener, Weed Fighter and Pest ably expected range of total N provided by a Fighter. If you know your main goal for a cover legume stand (from all biomass,above- and below crop, Chart 1 can suggest which cover crop ground) in lb. N/A, based mostly on published entries to examine in the charts that follow and research.This is total N, not the fertilizer replace- help you determine which major cover narra- ment value. Nonlegumes have not been rated for tive(s) to read first. their biomass nitrogen content, so this column is left blank for nonlegumes. Mature nonlegume Disclaimer. The crops recommended here will residues also tend to immobilize N. not be the most successful in all cases within a bioregion, and others my work better in some Dry Matter. A quantitative estimate of the locations and in some years. The listed cover range of dry matter in lb./A/yr., based largely on crops are, however, thought by reviewers to have published research.As some of this data is based the best chance of success in most years under on research plots, irrigated systems or multicut current management regimes. systems, your on-farm result probably would be CHART 2: PERFORMANCE AND ROLES in the low to midpoint of the dry matter range cited.This estimate is based on fully dry materi- This chart provides relative ratings (with the al. “Dry” alfalfa hay is often about 20 percent exception of two columns having quantitative moisture,so a ton of hay would only be 1,600 lb. ranges) of what the top covers do best, such as of “dry matter.” supply or scavenge nitrogen, build soil or fight erosion. N Scavenger. Rates a cover crop’s ability to take Seasonality has a bearing on some of these rat- up and store excess nitrogen. Bear in mind that ings.A cover that grows best in spring could sup- the sooner you plant a cover after main crop press weeds better than in fall. Unless otherwise harvest—or overseed a cover into the standing footnoted,however,the chart would rate a cover’s crop—the more N it will be able to absorb. performance (relative to the other covers) for the entire time period it is likely to be in the field. Soil Builder. Rates a cover crop’s ability to pro- Ratings are general for the species, based on mea- duce organic matter and improve soil structure. sured results and observations over a range of The ratings assume that you plan to use cover conditions. The individual narratives provide crops regularly in your cropping system to pro- more seasonal details.The added effect of a nurse vide ongoing additions to soil organic matter.

CHARTS 43 Erosion Fighter. Rates how extensive and how Type. Describes the general life cycle of the crop. quickly a root system develops, how well it holds soil against sheet and wind erosion and the influ- B = Biennial. Grows vegetatively during its first ence the growth habit may have on fighting wind year and, if it successfully overwinters, sets seed erosion. during its second year.

Weed Fighter. Rates how well the cover crop CSA = Cool-Season Annual. Prefers cool tem- outcompetes weeds by any means through its life peratures and depending on which Hardiness cycle, including killed residue. Note that ratings Zone it is grown in, could serve as a fall, winter for the legumes assume they are established with or spring cover crop. a small-grain nurse crop. SA = Summer Annual. Germinates and Good Grazing. Rates relative production, nutrit- matures without a cold snap and usually toler- ional quality and palatability of the cover as a forage. ates warm temperatures.

Quick Growth. Rates the speed of establishment WA = Winter Annual. Would be more cold-tol- and growth. erant and would require freezing temperature or a cold period to set seed. Lasting Residue. Rates the effectiveness of the cover crop in providing a long-lasting mulch. LP = Long-lived Perennial. Can endure for many growing seasons. Duration. Rates how well the stand can provide long-season growth. SP = Short-lived Perennial. Usually does not persist more than a few years, if that long. Harvest Value. Rates the cover crop’s economic value as a forage (F) or as a seed or grain crop (S), Hardy Through Zone. Refers to the standard bearing in mind the relative market value and USDA Hardiness Zones. See map on inside front probable yields. cover. Bear in mind that regional microclimate, weather variations, and other near-term manage- Cash Crop Interseed. Rates whether the cover ment factors such as planting date and compan- crop would hinder or help while serving as a ion species can influence plant performance companion crop. expectations. CHART 3A: CULTURAL TRAITS Tolerances. How well a crop is likely to endure This chart shows a cover crop’s characteristics despite stress from heat, drought, shade, flooding such as life cycle, drought tolerance, preferred or low fertility.The best rating would mean that soils and growth habits. The ratings are general the crop is expected to be fully tolerant. for the species, based on measured results and observations over a range of conditions.Choice of Habit. How plants develop. cultivar, weather extremes and other factors may C = Climbing affect a cover crop’s performance in a given year. U = Upright P = Prostrate Column headings SP = Semi-Prostrate Aliases. Provides a few common references for SU = Semi-Upright the cover crop.

44 MANAGING COVER CROPS PROFITABLY pH Preferred. The pH range in which a species cost will depend on actual seed cost and seeding can be expected to perform reasonably well. rate. Estimate excludes associated costs such as labor, fuel and equipment. Best Established. The season in which a cover crop is best suited for planting and early growth. Inoculant Type. The recommended inoculant Note that this can vary by region and that it’s for each legume. Your seed supplier may only important to ascertain local planting date rec- carry one or two common inoculants. You may ommendations for specific cover crops. need to order inoculant in advance. See Seed Season: F = Fall ; Sp = Spring; Su = Summer; Suppliers, p. 166. W = Winter Time: E = Early; L = Late; M = Mid Reseeds. Rates the likelihood of a cover crop re- establishing through self-reseeding if it’s allowed Minimum Germination Temperature. The to mature and set seed.Aggressive tillage will bury minimum soil temperature (F) generally required seed and reduce germination. Ratings assume the for successful germination and establishment. tillage system has minimal effect on reseeding. Dependable reseeding ability is valued in some CHART 3B: PLANTING orchard, dryland grain and cotton systems, but Depth. The recommended range of seeding can cause weed problems in other systems. See depth (in inches),to avoid either overexposure or the narratives for more detail. burying too deeply. CHARTS 4A AND 4B Rate. Recommended seeding rate for drilling and These charts provide relative ratings of other broadcasting a pure stand in lb./A, bu/A. and management considerations—benefits and possi- oz./100 sq.ft., assuming legal standards for germi- ble drawbacks—that could affect your selection nation percentage. Seeding rate will depend on of cover crop species. the cover crop’s primary purpose and other fac- The till-kill rating assumes tillage at an appro- tors. See the narratives for more detail about priate stage. The mow-kill ratings assume mowing establishing a given cover crop. Pre-inoculated at flowering,but before seedheads start maturing. (“rhizo-coated”) legume seed weighs about one- See sectional narratives for details. third more than raw seed. Increase seeding rate Ratings are based largely on a combination of by one-third to plant the same amount of seed per published research and observations of farmers area. who have grown specific covers.Your experience with a given cover could be influenced by site- Cost. Material costs (seed cost only) in dollars per specific factors, such as your soil condition, crop pound, based usually on a 50-lb. bag as of fall rotation, proximity to other farms, weather 1997. Individual species vary markedly with sup- extremes, etc. ply and demand. Always confirm seed price and CHART 4A: POTENTIAL ADVANTAGES availability before ordering, and before planning to use less common seed types. Soil Impact. Assesses a cover’s relative ability to loosen subsoil, make soil P and K more readily Cost/A. Seed cost per acre based on the midpoint available to crops, or improve topsoil. between the high and low of reported seed prices as of fall 1997 and the midpoint recommended Soil Ecology. Rates a cover’s ability to fight seeding rate for drilling and broadcasting. Your pests by suppressing or limiting damage from

CHARTS 45 nematodes, soil disease from fungal or bacterial likely pest risk. Overall, growing a cover crop infection, or weeds by natural herbicidal rarely causes pest problems. But certain cover (allelopathic) or competition/smothering action. crops occasionally may contribute to particular Researchers report difficulty in conclusively pest, disease or nematode problems in localized documenting allelopathic activity distinct from areas, for example by serving as an alternate host other cover crop effects, and nematicidal impacts to the pest. See the narratives for more detail. are variable, studies show.These are general, ten- tative ratings in these emerging aspects of cover Readers note the shift in meaning for symbols crop influence. on this chart only.

Other. Indicates likelihood of attracting benefi- Management Challenges. Relative ease or diffi- cial insects,of accommodating field traffic (foot or culty of establishing, killing or incorporating a vehicle) and of fitting growing windows or short stand.“Till-kill”refers to killing by plowing,disking duration. or other tillage. “Mature incorporation” rates the CHART 4B: POTENTIAL DISADVANTAGES difficulty of incorporating a relatively mature stand.Incorporation will be easier when a stand is Increase Pest Risks. Relative likelihood of a killed before maturity or after some time elapses cover crop becoming a weed,or contributing to a between killing and incorporating.

46 MANAGING COVER CROPS PROFITABLY Chart 1 TOP REGIONAL COVER CROP SPECIES1

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

1ryegrs=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.) Scavenger2 Builder3 Fighter4 Fighter Grazing5 Growth

Annual ryegrass p. 55 2,000–9,000

Barley p. 58 3,000–10,000

Oats p. 62 2,000–10,000

Rye p. 65 3,000–10,000

Wheat p. 72 3,000–7,000 NONLEGUMES 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

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 LEGUMES 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

1Total N—Total N from all plant. 2N Scavenger—Ability to take up/store excess nitrogen. 3Soil Builder—Organic matter yield and soil structure improvement. 4Erosion Fighter—Soil-holding ability of roots and total plant. 5Good Grazing—Production, nutritional quality and palatability. =Poor; =Fair; =Good; =Very Good; =Excellent

48 MANAGING COVER CROPS PROFITABLY Chart 2 PERFORMANCE AND ROLES continued

Lasting Harvest Cash Crop Species Residue1 Duration2 Value3 Interseed4 Comments F* S*

Annual ryegrass Heavy N and H20 user; cutting boosts dry matter significantly.

Barley Tolerates moderately alkaline conditions but does poorly in acid soil < pH 6.0.

Oats Prone to lodging in N-rich soil.

Rye Tolerates triazine herbicides.

Wheat Heavy N and H20 user in spring. NONLEGUMES Buckwheat Summer smother crop; breaks down quickly.

Sorghum–sudangrass Mid-season cutting increases root penetration.

Berseem clover Very flexible cover crop, green manure, forage.

Cowpeas Season length, habit vary by cultivar.

Crimson clover Established easily,grows quickly if planted early in fall; matures early in spring.

Field peas Biomass breaks down quickly.

Hairy vetch Bi-culture with small grain expands seasonal adaptability.

Medics Use annual medics for interseeding.

Red clover Excellent forage, easily established; widely adapted. LEGUMES Subterranean clover Strong seedlings, quick to nodulate.

Sweetclovers Tall stalks, deep roots in second year.

White clover Persistent after first year.

Woollypod vetch Reseeds poorly if mowed within 2 months of seeddrop; overgrazing can be toxic.

1Lasting Residue—Rates how long the killed residue remains on the surface. 2Duration—Length of vegetative stage. 3Harvest Value—Economic value as a forage (F) or as seed (S) or grain. 4Cash Crop Interseed—Rates how well the cover crop will perform with an appropriate companion crop. =Poor; =Fair; =Good; =Very Good; =Excellent

CHARTS 49 Chart 3A CULTURAL TRAITS

Hardy Tolerances Min. through pH Best Germin. Species Aliases Type1 Zone2 Habit3 (Pref.) Established4 Temp. heat drought shade flood low fert

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 NONLEGUMES 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

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 LEGUMES 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

1B=Biennial; CSA=Cool season annual; LP=Long-lived perennial; SA=Summer annual; SP=Short-lived perennial;WA=Winter annual 2See USDA Hardiness Zone Map, inside front cover. NFT=Not frost tolerant. 3C=Climbing; U=Upright; P=Prostrate; SP=Semi-prostrate; SU=Semi-upright. 4E=Early; M=Mid; L=Late; F=Fall; Sp=Spring; Su=Summer;W=Winter =Poor; =Fair; =Good; =Very Good; =Excellent 50 MANAGING COVER CROPS PROFITABLY Chart 3B PLANTING

Cost Cost/A Inoc. Species Depth Seeding Rate ($/lb.)1 (median)2 Type Reseeds3 Drilled Broadcast drilled broadcast lb./A bu/A lb./A bu/A oz./100 ft2

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

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

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

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

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

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

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

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

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

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

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

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

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

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

1 1 Subterranean clover /4– /2 10–20 20–30 3 2.50 37.50 62.50 clovers, R sub, rose

1 Sweetclovers /4–1.0 6–10 10–20 1.5 .70 5.60 10.50 alfalfa, R swt cl

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

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

1Per 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). 2Mid-point price at mid-point rate, seed cost only. 3R=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 NONLEGUMES Buckwheat p. 77

Sorghum–sudangrass p. 80

Berseem clover p. 87

Cowpeas p. 95

Crimson clover p. 100

Field peas p. 105

Hairy vetch p. 112

Medics p. 119

Red clover p. 127 LEGUMES Subterranean clover p. 132

Sweetclovers p. 139

White clover p. 147

Woollypod vetch p. 151

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

52 MANAGING COVER CROPS PROFITABLY Chart 4B POTENTIAL DISADVANTAGES

Increase Pest Risks Management Challenges

Species weed insects/ crop hinder mature Comments Pro/Con potential nematodes disease crops establish till-kill mow-kill incorp.

Annual ryegrass1 If mowing, leave 3-4" to ensure regrowth.

Barley Can be harder than rye to incorporate when mature.

Oats Cleaned, bin-run seed will suffice.

Rye Can become a weed if tilled at wrong stage.

Wheat Absorbs N and H20 heavily during

NONLEGUMES stem growth, so kill before then.

Buckwheat Buckwheat sets seed quickly.

Sorghum–sudangrass Mature, frost-killed plants become quite woody.

Berseem clover Multiple cuttings needed to achieve maximum N.

Cowpeas Some cultivars, nematode resistant.

Crimson clover Good for underseeding, easy to kill by tillage or mowing.

Field peas Susceptible to sclerotinia in East.

Hairy vetch Tolerates low fertility,wide pH range, cold or fluctuating winters.

Medics Perennials easily become weedy.

Red clover Grows best where corn grows well. LEGUMES

Subterranean clover Cultivars vary greatly.

Sweetclovers Mature plants become woody.

White clover Can be invasive; survives tillage.

Woollypod vetch Hard seed can be problematic; resident vegetation eventually displaces.

1Symbols, 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 results: The higher carbon residue is harder for crops are grasses. These include: soil microbes to break down,so the process takes • Annual cereals (rye, wheat, barley,oats) longer, and the nutrients contained in the cover • Annual or perennial forage grasses such as crop residue usually are less available to the next ryegrass crop. • Warm-season grasses like sorghum-sudangrass So although grass cover crops take up leftover N from the previous crop,as they mature the N is less Grass cover crops are most useful for: likely to be released for use by a crop grown imme- • Scavenging nutrients—especially N—left over diately after the grass cover crop. As an example of from a previous crop this, think of how long it takes for straw to decom- • Reducing or preventing erosion pose in the field.Over time,the residue does break • Producing large amounts of residue, and down and nutrients are released. In general, this adding organic matter to the soil slower decomposition and the higher carbon con- • Suppressing weeds tent of grasses can lead to increased soil organic Annual cereal grain crops have been used suc- matter, compared to legumes. cessfully in many different climates and cropping Grass cover crops can produce a lot of residue, systems.Winter annuals usually are seeded in late which contributes to their ability to prevent ero- summer or fall, establish and produce good root sion and suppress weeds while they are growing and topgrowth biomass before going dormant or when left on the soil surface as a mulch. during the winter,then green up and produce sig- Although grasses contain some nitrogen in nificant biomass before maturing. Rye, wheat, and their plant tissues, grass cover crops generally are hardy triticale all follow this pattern, with some not significant sources of N for your cropping sys- relatively small differences that will be addressed tem. They do, however, keep excess soil N from in the section for each cover crop. leaching, and prevent the loss of soil organic mat- Perennial and warm-season forage grasses also ter through erosion. can serve well as cover crops. Forage grasses, like Management of grasses in your cropping sys- sod crops, are excellent for nutrient scavenging, tem may involve balancing the amount of residue erosion control, biomass production and weed produced with the possibility of tying up N for control. Perennials used as cover crops are usual- more than one season. Mixtures of grass and ly grown for about one year. Summer-annual legume cover crops can alleviate the N-immobi- (warm-season) grasses may fill a niche for biomass lization effect, can produce as much or more dry production and weed or erosion control if the matter as a pure grass stand and may provide bet- ground would otherwise be left fallow (between ter erosion control due to the differences in vegetable crops, for example). Buckwheat, while growth habit.Suggestions for cover crop mixtures not a grass,is also a warm-season plant used in the are found in the individual cover crop sections. same ways as summer-annual grasses. In addition to grasses, another summer non- Grass cover crops are higher in carbon than legume is buckwheat, which is described in legume cover crops.The high carbon content of detail in its own section (p. 77). Buckwheat is grasses means that they will break down more usually classed as a non-grass coarse grain.While slowly than legumes, resulting in longer-lasting it is managed like a quick-growing grain, its has residue. As grasses mature, the carbon-to-nitrogen a succulent stem, large leaves and white ratio (C:N) increases. This has two tangible blossoms.

54 MANAGING COVER CROPS PROFITABLY 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.

f you want mellower soil without investing soil tilth.Rapid aboveground growth helps supply much in a cover crop, consider annual rye- organic matter. Expect about 4,000 to 6,000 lb. Igrass. A quick-growing, nonspreading bunch dry matter/A on average with a multicut regimen, grass, annual ryegrass is a reliable, versatile per- climbing as high as 9,000 lb.DM/A over a full field former almost anywhere, assuming adequate season with high moisture and fertility. moisture and fertility.It does a fine job of holding soil,taking up excess N and outcompeting weeds. Weed suppressor. Mixed with legumes or Ryegrass is an excellent choice for building soil grasses, annual ryegrass usually establishes first structure in orchards, vineyards and other crop- and improves early-season weed control. With land to enhance water infiltration, water-holding adequate moisture, it serves well in Hardiness capacity or irrigation efficiency.It can reduce soil Zone 6 and warmer as a living mulch in high- splash on solanaceous crops and small fruit crops, value systems where you can mow it regularly. It decreasing disease and increasing crop quality. may winterkill elsewhere, especially without pro- You also can overseed ryegrass readily into corn, tective snow cover during prolonged cold snaps. soybeans and many high-value crops. Even so, its quick establishment in fall still would provide an excellent,winterkilled mulch for early- BENEFITS spring weed suppression.

Erosion fighter. Ryegrass has an extensive, Nutrient catch crop. A high N user, ryegrass can soil-holding root system. The cover crop estab- capture leftover N and reduce nitrate leaching over lishes quickly even in poor,rocky or wet soils and winter. Its extensive, fibrous root system can take tolerates some flooding once established.It’s well- up as much as 43 lb. N/A, a University of California suited for field strips, grass waterways or exposed study showed (367). It took up about 60 lb. N/A areas. “An added bonus: It keeps you out of the by mid-May following corn in a Maryland study. mud at harvest,” says Pennsylvania grower Bob Cereal rye scavenged the same amount of N by Hofstetter. mid-April on this silt loam soil (307).

Soil builder. Ryegrass’s dense yet shallow root Nurse/companion crop. Ryegrass helps slow- system improves water infiltration and enhances growing, fall-seeded legumes establish and over-

ANNUAL RYEGRASS 55 however, especially with late-fall plantings. Drill 5 1 1 to 10 lb./A, /4 to /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.

Winter annual use. Seed in fall in Zone 6 or warmer. In Zone 5 and colder, seed from mid- summer 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

Marianne Sarrantonio pounds of red or white clover with it) or plant right after corn silage harvest.Overseed at leaf-yel- ANNUAL RYEGRASS (Lolium multiflorum) lowing or later for dense-canopy crops such as soybeans (147, 150). When overseeding into solanaceous crops such as peppers, tomatoes and winter in the northern U.S., even if the ryegrass eggplant, wait until early to full bloom. winterkills.It tends to outcompete legumes in the South. Ryegrass also is a very palatable forage.You Spring seeding. Sow ryegrass right after an can extend the grazing period in late fall and early early-spring vegetable crop, for a four- to eight- spring by letting livestock graze cover crops of week summer period before a fall vegetable ryegrass or a ryegrass-based mix. crop (302).

MANAGEMENT Mixed seeding. Plant ryegrass at 8 to 15 lb./A with a legume or small grain, either in fall or early Ryegrass prefers fertile, well-drained loam or sandy in spring. Ryegrass will dominate the mixture loam soils, but establishes well on many soil types, unless you plant at low rates or mow regularly. including poor or rocky soils. It tolerates clay or Seed the legume at about two-thirds its normal poorly-drained soils in a range of climates and will rate. Adequate P and K levels are important when outperform small grains on wet soils (350). growing annual ryegrass with a legume. Annual ryegrass has a biennial tendency in cool In vineyards,a fall-seeded,50:50 mix of ryegrass regions. If it overwinters, it will regrow quickly and crimson clover works well, some California and produce seed in late spring. Although few growers have found (167). plants survive more than a year, this reseeding Although not a frequent pairing, drilling rye- characteristic can create a serious weed problem grass in early spring at 20 lb./A with an oats nurse in some areas, such as the mid-Atlantic (82). crop or frost seeding 10 lb./A into overwintered small grains can provide some fine fall grazing. Establishment & Fieldwork Frost seeding with red clover or other large-seed- Annual ryegrass germinates and establishes well ed, cool-season legumes also can work well. even in cool soil (350). Broadcast seed at 15 to 30 lb./A.You needn’t incorporate seed when broad- Maintenance. Avoid overgrazing or mowing rye- casting onto freshly cultivated soil—the first grass closer than 3 to 4 inches. A stand can persist shower ensures seed coverage and good germina- many years in orchards,vineyards,and other areas tion. Cultipacking can reduce soil heaving, if allowed to reseed naturally and not subject to

56 MANAGING COVER CROPS PROFITABLY prolonged heat, cold or drought.That’s rarely the Rust occasionally can be a problem with annu- case in Zone 5 and colder, however, where al ryegrasses, especially crown and brown rust. climate extremes take their toll.Perennial ryegrass Look for resistant, regionally adapted varieties. may be a smarter choice if persistence is impor- Annual ryegrass also can host high densities of pin tant. Otherwise, plan on incorporating the cover nematodes (Paratylenchus projectus) and within a year of planting. Annual ryegrass is a bromegrass mosaic virus, which plant-parasitic relatively late maturing plant, so in vineyards nematodes (Xiphinema spp.) transmit (351). it may use excessive water and N if left too long (168). Other Options Ryegrass provides a good grazing option that can Killing & Controlling extend the grazing season for almost any kind of You can kill annual ryegrass mechanically by disk- livestock. Although very small-seeded, ryegrass ing or plowing, preferably during early bloom does not tiller heavily, so seed at high rates if you (usually in spring), before it sets seed (302, 351). expect a ryegrass cover crop also to serve as a pas- Mowing may not kill ryegrass completely (77). ture. Some varieties tolerate heat fairly well and You also can kill annual ryegrass readily with non- can persist for several years under sound grazing persistent contact herbicides such as glyphosate practices that allow the grass to reseed. or paraquat.When soil moisture conservation is a As a hay option, annual ryegrass can provide primary objective of the killed surface residue, 2,000 to 6,000 pounds of dry forage per acre, paraquat would be better because it kills fast and depending on moisture and fertility levels (351). conserves more moisture (82). For highest quality hay,cut no later than the early To minimize N tie-up as the biomass decom- bloom stage and consider growing it with a poses, wait a few weeks after incorporation legume. before you seed a subsequent crop. Growing rye- When using ryegrass for grass waterways and grass with a legume such as red clover would min- conservation strips on highly erodible slopes, imize the N concern. By letting the cover residue applying 3,000 to 4,000 pounds per acre of straw decompose a bit,you’ll also have a seedbed that is after seeding at medium to high rates can help easier to manage. keep soil and seed in place until the stand establishes (351). Pest Management Weed potential. Ryegrass can become a weed if Management Cautions allowed to set seed (302). It often volunteers in Ryegrass is a heavy user of moisture and N. It vineyards or orchards if there is high fertility and performs poorly during drought or long periods may require regular mowing to reduce competi- of high or low temperature, and in low-fertility tion with vines (351).A local weed management soils. It can compete heavily for soil moisture specialist may be able to recommend a herbicide when used as living mulch. It also can become a that can reduce ryegrass germination if the cover weed problem (302). is becoming a weed in perennial grass stands. Chlorsulfuron is sometimes used for this purpose COMPARATIVE NOTES in California (351). • Establishes faster than perennial ryegrass but Insect and other pests. Ryegrass attracts few is less cold-hardy insect pests and generally can help reduce insect • Less persistent but easier to incorporate than pest levels in legume stands and many vegetable perennial ryegrass crops, such as root crops and brassicas. Rodents • About half as expensive as perennial ryegrass are occasionally a problem when ryegrass is used as a living mulch. 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

See charts, pp. 47 to 53, for ranking and management summary.

nexpensive and easy to grow, barley provides Nutrient recycler. Considered a light N feeder, exceptional erosion control and weed sup- barley captured 32 lb. N/A as a winter cover crop Ipression in semi-arid regions and in light soils. following a stand of fava beans (Vicia faba) in a It also can fill short rotation niches or serve as a California study,compared with 20 lb./A for annu- topsoil-protecting crop during droughty condi- al ryegrass. A barley cover crop reduced soil N tions in any region. an average of 64 percent at eight sites throughout It’s a fine choice for reclaiming overworked, North America that had received an average of weedy or eroded fields, or as part of a cover crop 107 lb. N/A (213). Intercropping barley with field mix for improving soil tilth and nutrient cycling in peas (Pisum sativum) can increase the amount perennial cropping systems in Hardiness Zone 8 of N absorbed by barley and returned to the soil or warmer. in barley residue, other studies show (172, 175). Barley prefers cool,dry growing areas. A spring Barley improves P and K cycling if the residue cover crop,it can be grown farther north than any isn’t removed. other cereal grain, largely because of its short growing period.It also can produce more biomass Weed suppressor. Quick to establish,barley out- in a shorter time than any other cereal crop (219). competes weeds largely by absorbing soil moisture during its early growing stages. It also shades BENEFITS out weeds and releases allelopathic chemicals that help suppress them. Erosion control. Use barley as an overwintering cover crop for erosion control in Zone 8 and Tilth-improving organic matter. Barley is a warmer, including much of California, western quick source of abundant biomass that, along Oregon and western Washington. It’s well-suited with its thick root system, can improve soil for vineyards and orchards, or as part of a mixed structure and water infiltration (219, 367). In seeding. California cropping systems, cultivars such as As a winter annual, barley develops a deep, UC476 or COSINA can produce as much as 12,900 fibrous root system. The roots can reach as deep lb. biomass/A. as 6.5 feet. As a spring crop, barley has a comparatively shallow root system but holds soil strongly to Nurse crop. Barley has an upright posture and minimize erosion during droughty conditions (51). relatively open canopy that makes it a fine nurse

58 MANAGING COVER CROPS PROFITABLY crop for establishing a forage or legume stand. Winter annual use. For an overwintering cover Less competitive than winter grains, barley also crop in Zone 8 or warmer, plant barley from uses less water than other covers.In weedy fields, September through February. Plantings before wait to broadcast the forage or legume until after November 1 generally fare best, largely due to you’ve mechanically weeded barley at the four- or warmer soil conditions. Elsewhere, winter vari- five-leaf stage to reduce weed competition. eties might overwinter only in mild areas with As an inexpensive,easy-to-kill companion crop, adequate snow cover. barley can protect sugarbeet seedlings during Expect mixed results if trying to use barley as a their first two months while also serving as a soil self-reseeding cover crop.Weather variations,mow- protectant during droughty periods (details ing regimes and the return of native or resident below). vegetation tend to reduce barley’s reseeding capabili- Pest suppression. Barley A fast-growing barley can ty. Expect to resow periodi- can reduce incidence of be grown farther north and cally,perhaps annually. leafhoppers, aphids, armyworms, root-knot nematodes produce more biomass in a Mixed seedings. Barley and other pests, a number of shorter time than any other works well in mixtures with studies suggest. other grasses or legumes. In cereal grain. low-fertility soils or where MANAGEMENT you’re trying to minimize tie-up of soil nitrogen, growing barley with one or Establishment & Fieldwork more legumes can be helpful. Your seeding cost Barley establishes readily in prepared seedbeds. It per pound will increase, but the reduced seeding prefers adequate but not excessive moisture and rate can offset some of this. A short-season does poorly in waterlogged soils. It grows best in Canadian field pea such as TRAPPER would be a well-drained, fertile loams or light, clay soils in good companion, or try an oat/barley/pea mix, areas having cool, dry, mild winters. It also does suggests organic farmer Jack Lazor,Westfield,Vt. well on light, droughty soils and tolerates some- In northern California, Phil LaRocca (LaRocca what alkaline soils better than other cereal crops. Vineyards, Forest Ranch, Calif.) lightly disks his With many varieties of barley to choose from, upper vineyard’s soil before broadcasting a mix be sure to select a regionally adapted one. Many of barley, fescue, brome, LANA vetch, and crim- are well-adapted to high altitudes and cold, short son, red and subterranean clovers, usually during growing seasons. October. He seeds at 30 to 35 lb./A, with 10 to 20 percent being barley. “I’ve always added Spring annual use. Drill at 50 to 100 lb./A (1 to more barley to the seeding rate than recom- 3 2 bushels) from /4 to 2 inches deep into a pre- mended. More is better, especially with barley, pared seedbed. Hoe or furrow-type drills with if you want biomass and weed suppression,” disk- or double-disk openers work well in arid he says. regions without irrigation. After broadcasting, LaRocca covers erosion- If broadcasting, prepare the seedbed with at prone areas with 2 tons of rice straw per acre, least a light field cultivation. Sow 80 to 125 lb./A which is “$1 cheaper per bale than oat straw here (1.5 to 2.5 bushels) and harrow, cultipack or disk and has fewer weed seeds,”he notes.“The straw lightly to cover. Use a lower rate (25 to 50 decomposes quickly and holds seed and soil pounds) if overseeding as a companion crop or a well.”Besides contributing to soil humus (as the higher rate (140 pounds) for very weedy fields. cover crop also does), the straw helps keep the When broadcasting, consider seeding half in one seedbed warm and moist. That can be very direction, then the rest in a perpendicular direc- helpful in LaRocca’s upper vineyard, where it tion for better coverage (51). sometimes snows in winter.

BARLEY 59 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

Elayne SearsElayne control in his sugarbeets.Another control option is a single application of a herbicide labeled for BARLEY (Hordeum vulgare) grass control (37).

Killing In his other, less-erodible vineyard, LaRocca Kill barley with a grass herbicide in late spring, or disks up the cover vegetation, then runs a harrow by disking or mowing at the mid- to late-bloom quickly on top of the disked alleyways to set a stage but before it starts setting seed. seedbed before broadcasting and cultipacking a If plant-parasitic nematodes have been a prob- similar mix of cover crops. lem, incorporate overwintered barley early in spring, before warm temperatures encourage Field Management nematode populations. Although barley absorbs a lot of water in its early stages,it uses moisture more efficiently than other Pest Management cereals and can be grown without irrigation. Annual weeds and lodging can occur when grow- About half the commercial barley acreage in drying barley in high-fertility soils, although these land areas is irrigated, however. California crop- wouldn’t pose problems in a barley cover crop. ping systems that include barley tend to be Despite their less dense canopy, six-rowed vari- irrigated as well. Low seeding rates won’t neces- eties tend to be taller and more competitive sarily conserve moisture, as vegetative growth against weeds than two-rowed varieties. If you’re often increases. considering a grain option, harrowing or hoeing LaRocca hasn’t had any moisture problems or just before barley emergence could reduce weeds grape-yield concerns from growing barley or that already have sprouted. other cover crops, even in the 40 percent of his Barley produces alkaloids that have been upper vineyard that isn’t furrow-irrigated.“Once shown to inhibit germination and growth of your vines are established, their root system is white mustard (196).These exudates also protect

60 MANAGING COVER CROPS PROFITABLY barley plants from fungus, armyworm larvae, Other Options bacteria and aphids (197, 374). Barley can be grazed lightly in winter or spring or Barley seems to reduce the incidence of grape cut for hay/haylage (147). It has greater forage leafhoppers in vineyards and increase levels nutritive value than oats, wheat or triticale. It also of beneficial spiders, one California grower can be grown as a specialty grain for malting, observed (167). Growing high-biomass cover soups, bread and other uses. As a feed grain (in a crops such as barley or rye increased populations hog ration, for example), it can replace some of centipedes,predator mites and other important costlier corn. predators, independent of tillage system used, a study in the Pacific Northwest found (366). COMPARATIVE NOTES Cutworms and other small grain pests can be occasional problems. Some perennial crop grow- • Barley tillers more than oats and also is more ers in California report increased incidence of drought-tolerant, but oats generally perform gophers when growing cover crop mixes and try better as a companion crop or winterkilled to minimize this by encouraging owl populations. nurse crop because they are less competitive Avoid seeding in cold, damp soils, which makes than barley (325). barley more prone to fungus and disease. Assum- • Barley tolerates alkaline soils better than any ing adequate soil moisture, shallow seeding can other cereal. hasten emergence and lessen incidence of root rot • Winter cultivars are less winterhardy than win- disease, if this has been a problem in your area ter wheat, triticale or cereal rye. (325). Varieties resistant to leaf diseases are available. Two-rowed varieties are more resistant to SEED leaf rust and mildew. Also avoid planting barley after wheat. Cultivars. Many commercial varieties are avail- If nematodes are likely to be a problem, plant able. Look for low-cost, regionally adapted culti- late in fall or during winter to avoid warm-season vars with at least 95-percent germination. growth and incorporate early in spring in Zone 8 Six-rowed cultivars are better for overseeding, and warmer. Barley can be a host for a nematode and are more heat- and drought-tolerant. Two- species (Meloidogyne javanica) that adversely rowed types have more symmetrical kernels and affects Thompson seedless grapes. are more disease-resistant (e.g. leaf rust and Barley drastically reduced root-knot nematode mildew) than six-rowed types, in which two- (Meloidogyne hapla M. Chitwood) populations thirds of the lateral rows of the spike are smaller and increased marketable carrot yields by at least and twisted. seventeen-fold in a Quebec study comparing three-year rotations (191.1). Seed sources. Widely available.

BARLEY 61 OATS Avena sativa

Also called: spring oats

Type: cool season annual cereal

Roles: suppress weeds, prevent erosion, scavenge excess nutrients, add biomass, nurse crop

Mix with: clover, pea, vetch or other legumes

See charts, pp. 47 to 53, for ranking nonsummer use CSA and management summary.

f you need a low-cost, reliable fall cover that crops look even better in the southeastern U.S., winterkills in Hardiness Zone 6 and colder and generally about $25 per acre (287). Imuch of Zone 7, look no further. Oats provide quick, weed-suppressing biomass, take up excess Nutrient catch crop. Oats take up excess N and soil nutrients and can improve the productivity of small amounts of P and K when planted early legumes when planted in mixtures. The cover’s enough. Late-summer plantings can absorb as fibrous root system also holds soil during cool- much as 77 lb. N/A in an eight- to ten-week peri- weather gaps in rotations,and the ground cover pro- od, studies in the Northeast and Midwest have vides a mellow mulch before low-till or no-till crops. shown (252, 268). An upright,annual grass,oats thrive under cool, Where the plant winterkills, some farmers use moist conditions on well-drained soil. Plants can oats as a nitrogen catch crop after summer reach heights in excess of 4 feet. Stands generally legume plowdowns, to hold some legume N over fare poorly in hot, dry weather. winter without needing to kill the cover in spring. Some of that N disappears by spring, either BENEFITS through denitrification into the atmosphere or by leaching from the soil profile. Consider mixing You can depend on oats as a versatile,quick-grow- oats with an overwintering legume if spring nitro- ing cover for many benefits: gen is your main concern.

Affordable biomass. With good growing condi- Smother crop. Quick to germinate, oats are a tions and sound management (including timely great smother crop that outcompetes weeds and planting), expect 2,000 to 4,000 pounds of dry also provides allelopathic residue that can hinder matter per acre from late-summer/early fall-seed- germination of many weeds—and some crops ed oats and up to 8,000 pounds per acre from (see below)—for a few weeks. Reduce crop sup- spring stands. Seeding (whether broadcasting or pression concerns by waiting three weeks after drilling), labor, equipment and management costs killing oats before planting a subsequent crop. for a fall oat stand averaged less than $40/A for a group of northwestern Washington growers in a Fall legume nurse crop. Oats have few equals recent study. Budgets for seeding cereal cover as a legume nurse crop or companion crop.They

62 MANAGING COVER CROPS PROFITABLY can increase the fertilizer replacement value of One low-cost seeding method is to set the com- legumes, studies have shown. Adding about 35 bine so it blows the lightweight oats out the back to 75 lb. oats/A to the seeding mix helps slow- at about 2 to 4 bushels per acre. Disk lightly to establishing legumes such as hairy vetch, clovers incorporate. In many regions, you’ll have the or winter peas, while increasing biomass. It also option of letting it winterkill or sending in cattle helps reduce fall weeds. The oats will winterkill for some fall grazing. in many areas while improving the legume’s If seeding oats as a fall nurse crop for a legume, winter survival. a low rate (1 to 2 bushels per acre) works well. If drilling oats, seed at 2 to 3 bushels per acre 1 Spring green manure or companion crop. /2 to 1 inch deep, or 2 inches when growing Spring-seeded with a legume, oats can provide grain you plan to harrow for weed control.When hay or grain and excellent straw in the Northern seeding into residue, a good no-till drill can save U.S., while the legume remains as a summer—or time and also provide a firm seedbed that even later—cover. There’s also a haylage option legumes like (102). with a fast-growing legume if you harvest when Shallow seeding in moist soil provides rapid oats are in the dough stage. The oats will increase emergence and reduces incidence of root rot dis- the dry matter yield and boost the total protein, ease. Drilling spring oats in fall can provide but could pose a nitrate-poison- seedlings with slightly more frost ing threat, especially if you delay Oats are a reliable, resistance than broadcasting and harvesting until oats are nearing could extend the growing season the flowering stage. low-cost cover that a bit if you can’t fit in a late- The climbing growth habit of winterkill in Zone 6 summer seeding. some viny legumes such as vetch Timing is critical when you can contribute to lodging and and much of Zone 7. want plenty of biomass or a make oat grain harvest difficult. thick ground cover. Overseeding If you’re growing the legume for seed, the oats the large-seeded oats into a standing crop or can serve as a natural trellis that eases combining. heavy residue could be difficult. As a winter cover following soybeans in the Northeast or MANAGEMENT Midwest, however, overseeding spring oats at the leaf-yellowing or early leaf-drop stage (and Establishment & Fieldwork with little residue present) can give a combined Time seeding to allow at least six to 10 weeks of ground cover as high as 80 percent through cool-season growth. Moderately fertile soil gives early winter (156). If you wait until closer to or the best stands. after soybean harvest, however, you’ll obtain much less oat biomass to help retain bean Late-summer/early-fall planting. For a win- residue, Iowa and Pennsylvania studies have terkilled cover, spring oats usually are seeded in shown. late summer or early fall in Zone 7 or colder. Delaying planting by as little as two weeks Broadcasting or overseeding will give the best in late summer also can reduce the cover’s results for the least cost, unless planting into effectiveness as a spring weed fighter, a study in heavy residue. Cleaned, bin-run seed will suffice. upstate New York showed. By spring, oat plots If broadcasting and you want a thick win- that had been planted on August 25 had 39 terkilled mulch, seed at the highest locally recom- percent fewer weed plants and one-seventh mended rate (probably 3 to 4 bushels per acre) the weed biomass of control plots with no at least 40 to 60 days before your area’s first oat cover, while oats planted two weeks later killing frost. Assuming adequate moisture for had just 10 percent fewer weed plants in spring quick germination,the stand should provide some and 81 percent of the weed biomass of control soil-protecting, weed-suppressing mulch. plots (268, 269).

OATS 63 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.

Pest Management Allelopathic (naturally occurring herbicidal)

Marianne Sarrantonio compounds in oat roots and residue can hinder weed growth for a few weeks.These compounds OATS (Avena sativa) also can slow germination or root growth of some subsequent crops, such as lettuce, cress, timothy, rice, wheat and peas. Minimize this effect by wait- No-hassle fieldwork. As a winterkilled cover, ing three weeks after oat incorporation before just light disking in spring will break up the brit- seeding a susceptible crop, or by following with tle oat residue. That exposes enough soil for an alternate crop. Rotary hoeing or other pre- warming and timely planting. Or, no-till directly emerge mechanical weeding of solo-seeded oats into the mulch, as the residue will decompose can improve annual broadleaf control. readily early in the season. Oats are less prone to insect problems than wheat or barley. If you’re growing oats for Winter planting. As a fall or winter cover crop grain or forage, armyworms, various grain aphids in Zone 8 or warmer, seed oats at low to medium and mites, wireworms, cutworms, thrips, leaf- rates.You can kill winter-planted oats with spring hoppers, grubs and billbugs could present plowing, or with herbicides in reduced-tillage occasional problems. systems. Resistant oat varieties can minimize rusts, smuts and blights if they are a concern in your area Spring planting. Seeding rate depends on your or for your cropping system. Cover crops such as intended use: medium to high rates for a spring oats help reduce root-knot nematodes and green manure and weed suppressor, low rates for vegetable crop diseases caused by Rhizoctonia, mixtures or as a legume companion crop. Higher preliminary results of a producer study in South rates may be needed for wet soils or thicker Carolina show (369). To reduce harmful nema- ground cover. Excessive fertility can encourage todes that oats could encourage, avoid planting lodging, but if you’re growing oats just for its oats two years in a row or after nematode- cover value,that can be an added benefit for weed susceptible small grains such as wheat, rye or suppression and moisture conservation. triticale (51).

Easy to kill. When oats are grown as a green Other Options manure and weed suppressor before an annual There are many low-cost, regionally adapted and cash crop, kill the oat stand by mowing or spray- widely available oat varieties, so you have hay, ing soon after the vegetative stage, such as the straw, forage or grain options. Select for

64 MANAGING COVER CROPS PROFITABLY cultural and local considerations that best fit your if it’s the primary forage (176). Underseeding a intended uses. Day-length, stalk height, resistance legume enhances the forage option for oats by to disease, dry matter yield, grain test weight and increasing the biomass (compared with solo- other traits may be important considerations. In cropped oats) and providing nitrogen for a subse- the Deep South, fast-growing black oats (Avena quent crop. strigosa) look promising as a weed-suppressive cover for soybeans (287). See Up-and-Coming COMPARATIVE NOTES Cover Crops (p. 158). Aside from their value as a cover crop, oats are • Fall brassicas grow faster, accumulate more N a great feed supplement, says grain and hog and may suppress weeds better than oats. farmer Carmen Fernholz, Madison, Minn. A niche • Rye grows more in fall and early spring, market for organic oats also could exist in your absorbs more N and matures faster, but is area, he observes. harder to establish, to kill and to till than oats. Oats are more palatable than rye and easily • As a legume companion/nurse crop, oats out- overgrazed. If using controlled grazing in oat perform most varieties of other cereal grains. stands, watch for high protein levels, which can • Oats are more tolerant of wet soil than is vary from 12 to 25 percent (356).The potassium barley,but require more moisture. level of oat hay also is sometimes very high and could cause metabolic problems in milking cows Seed sources. Widely available.

RYE Secale cereale

Also called: cereal rye, winter rye, grain rye

Type: cool season annual cereal grain

Roles: take up excess N, prevent erosion, add organic matter, suppress weeds, companion crop

Mix with: legumes, grasses or other cereal grains

See charts, pp. 47 to 53, for ranking and management summary.

he hardiest of cereals, rye can be seeded pression. Inexpensive and easy to establish, rye later in fall than other cover crops and still outperforms all other cover crops on infertile, Tprovide considerable dry matter, an exten- sandy or acidic soil or on poorly prepared land. It sive soil-holding root system,significant reduction is widely adapted, but grows best in cool, temper- of nitrate leaching and exceptional weed sup- ate zones or high altitudes.

RYE 65 Taller and quicker-growing than wheat, rye can or before or after soybeans, fruits or vegetables. serve as a windbreak and trap snow or hold rain- It’s not the best choice before a small grain crop fall over winter. It overseeds readily into many such as wheat or barley unless you can kill rye high-value and agronomic crops and resumes reliably and completely, as volunteer rye seed growth quickly in spring, allowing timely killing would lower the value of other grains. by mowing or herbicides. Pair rye with a winter Rye also works well as a strip cover crop and annual legume such as hairy vetch to offset rye’s windbreak within vegetables or fruit crops and tendency to tie up soil nitrogen in spring. as a quick cover for rotation gaps or if another crop fails. BENEFITS You can overseed rye into tasseling or silking corn with consistently good results.You also can Nutrient catch crop. Rye is the best cool-season overseed rye into brassicas (304, 351), into soy- cereal cover for absorbing unused soil N.It has no beans just before leaf drop or between pecan tree taproot, but rye’s quick-growing, fibrous root sys- rows (43). tem can take up and hold as much as 100 lb. N/A until spring, with 25 to 50 lb. N/A more typical Plentiful organic matter. An excellent source (351). Early seeding is better than late seeding for of residue in no-till and minimum-tillage systems scavenging N (30). and as a straw source, rye provides up to 10,000 • A Maryland study credited rye with holding pounds of dry matter per acre, with 3,000 to 60 percent of the residual N that could have 4,000 pounds typical in the Northeast (302). A leached from a silt loam soil following rye cover crop might yield too much residue, intentionally over-fertilized depending on your tillage system, corn (307). Rye can be planted so be sure your planting regime for • A Georgia study estimated rye subsequent crops can handle this. captured from 69 to 100 per- later in fall than Rye overseeded into cabbage cent of the residual N after a other cover crops. August 26 covered nearly 80 per- corn crop (177). cent of the between-row plots by • In an Iowa study,overseeding mid-October and, despite some rye or a rye/oats mix into soybeans in August summer heat,already had accumulated nearly half limited leaching loss from September to May a ton of biomass per acre in a New York study.By to less than 5 lb. N/A (252). the May 19 plowdown, rye provided 2.5 tons of Rye increases the concentration of exchange- dry matter per acre and had accumulated 80 lb. able potassium (K) near the soil surface, by bring- N/A. Cabbage yields weren’t affected, so competi- ing it up from lower in the soil profile (94). tion wasn’t a problem (268). Rye’s rapid growth (even in cool fall weather) helps trap snow in winter, further boosting win- Weed suppressor. Rye is one of the best cool terhardiness. The root system promotes better season cover crops for outcompeting weeds, drainage, while rye’s quick maturity in spring— especially small-seeded, light-sensitive annuals compared with other cover crops—can help con- such as lambsquarters, redroot pigweed, vel- serve late-spring soil moisture. vetleaf, chickweed and foxtail. Rye also suppresses many weeds allelopathically (as a natural Reduces erosion. Along with conservation tillage herbicide), including dandelions and Canada this- practices, rye provides soil protection on sloping tle (300) and has been shown to inhibit germina- fields and holds soil loss to a tolerable level (95). tion of some triazine-resistant weeds (275). Rye reduced total weed density an average of Fits many rotations. In most regions, rye can 78 percent when rye residue covered more than serve as an overwintering cover crop after corn 90 percent of soil in a Maryland no-till study

66 MANAGING COVER CROPS PROFITABLY (339), and by 99 percent in a California study Companion crop/legume mixtures. Sow (351). You can increase rye’s weed-suppressing rye with legumes or other grasses in fall or effect before no-till corn by planting rye with overseed a legume in spring. A legume helps off- an annual legume such as hairy vetch (82). set rye’s tendency to tie up N. A legume/rye mixture adjusts to residual soil N levels. If there’s Pest suppressor. While rye is susceptible to the plenty of N, rye tends to do better; if there is same insects that attack other cereals, serious insufficient N, the legume component grows infestations are rare.Rye reduces insect pest prob- better, Maryland research shows (59). Hairy lems in rotations (369) and attracts significant vetch and rye are a popular mix, allowing an numbers of beneficials such as lady beetles (38). N credit before corn of 50 to 100 lb. N/A. Fewer diseases affect rye than other cereals. Rye also helps protect the less hardy vetch Rye can help reduce root-knot nematodes and seedlings through winter. other harmful nematodes, research in the South suggests (14, 369).

Rye Smothers Weeds Before Soybeans An easy-to-establish rye cover crop helps recommended rate—and sometimes add Napoleon, Ohio, farmer Rich Bennett enrich 1 quart of Lasso to control nightshade. Adding his sandy soil while trimming input costs in 1.7 pounds of ammonium sulfate and 13 no-till soybeans. Bennett broadcasts rye at 2 ounces of surfactant per acre makes it easier bushels per acre on corn stubble in late for Roundup to penetrate rye leaves,”he October. He chops the cornstalks after rye explains. seeding to ensure easy bean planting and The cover dies in about two weeks.The cultivation in spring. slow kill helps rye suppress weeds while Bennett doesn’t incorporate rye seed, soybeans establish. In this system, Bennett having found that it germinates well on the doesn’t have to worry about rye regrowing. soil surface under the chopped cornstalks. It He usually cultivates beans twice, using usually breaks through the ground but shows a Buffalo no-till cultivator that handles rye little growth before winter dormancy.Seeded residue easily.Bennett figures the rye saves earlier in fall, rye would provide more residue him $15 to $30 per acre in material costs than Bennett prefers by bean planting—and and fieldwork, compared with conventional more effort to kill the cover. “Even if I don’t no-till systems for soybeans. see any rye in fall, I know it’ll be there in Rye doesn’t hurt his bean yields, either. spring, even if it’s a cold or wet one,”he says. Usually at or above county average, his yields By mid-May,the rye is usually at least 2.5 range from 45 to 63 bushels per acre, feet tall and hasn’t started heading.“If it’s depending on rainfall, says Bennett. shorter than 15 to 18 inches, rye won’t do “I really like rye’s soil-saving benefits,”he a good enough job of shading out broadleaf says.“Rye reduces our winter wind erosion, weeds,”notes Bennett, who likes how rye improves soil structure, conserves soil suppresses foxtail, pigweed and lambsquarters. moisture and reduces runoff.”Although he He sprays the rye with herbicide and no-tills figures the rye’s restrained growth (from beans at 70 pounds per acre on 30-inch rows the late fall seeding) provides only limited in a single pass to minimize rye knockdown scavenging of leftover N, any that it does from field equipment.“I kill the rye with 1.5 absorb and hold overwinter is a bonus. pints of Roundup per acre—about half the

RYE 67 (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

Marianne Sarrantonio http://www2.epix.net/~cmfarm). CEREAL RYE (Secale cereale) Mixed seeding. Plant rye at the lowest locally recommended rate when seeding with a legume MANAGEMENT (302), and at low to medium rates with other grasses.In a Maryland study,a mix of 42 pounds of Establishment & Fieldwork rye and 19 pounds of hairy vetch per acre was the Rye prefers light loams or sandy soils and will ger- optimum fall seeding rate before no-till corn on a minate even in fairly dry soil. It also will grow in silt loam soil (61). If planting with clovers, seed heavy clays and poorly drained soils, and many rye at a slightly higher rate, about 56 lb. per acre. cultivars tolerate waterlogging. (44.1) For transplanting tomatoes into hilly, erosion- Rye can establish in very cool weather. It will prone soil, Steve Groff fall-seeds a per-acre mix of germinate at temperatures as low as 34 F. 30 pounds rye, 25 pounds hairy vetch and 10 Vegetative growth requires 38 F or higher (302). pounds crimson clover. He likes how the three- way mix guarantees biomass, builds soil and pro- Winter annual use. Seed from late summer to vides N. midfall in Hardiness Zones 3 to 7 and from fall to midwinter in Zones 8 and warmer. In the Upper Spring seeding. Although it’s not a common Midwest and cool New England states, seed two practice, you can spring seed cereals such as rye to eight weeks earlier than a wheat or rye grain as a weed-suppressing companion, relay crop or crop to ensure maximum fall, winter and spring early forage. Because it won’t have a chance to growth. Elsewhere, your tillage system and the vernalize (be exposed to extended cold after ger- amount of fall growth you prefer will help deter- mination), the rye can’t set seed and dies on its mine planting date. Early planting increases the own within a few months in many areas. This amount of N taken up before winter, but can provides good weed control in asparagus, says make field management (especially killing the Rich de Wilde,Viroqua,Wis. (86). cover crop and tillage) more difficult in spring. After drilling a large-seeded summer crop See Rye Smothers Weeds Before Soybeans (p. 67). such as soybeans, try broadcasting rye. The cover Rye is more sensitive to seeding depth than grows well if it’s a cool spring, and the summer other cereals, so plant no deeper than 2 inches crop takes off as the temperature warms up. (51). Drill 60 to 120 lb./A (1 to 2 bushels) into a Secondary tillage or herbicides would be neces- prepared seedbed or broadcast 90 to 160 lb./A sary to keep the rye in check and to limit the (1.5 to 3 bushels) and disk lightly or cultipack cover crop’s use of soil moisture.

68 MANAGING COVER CROPS PROFITABLY Killing & Controlling the covers before planting a crop. This ensures Nutrient availability concern. Rye grows and adequate soil warming,dry enough conditions for matures rapidly in spring, but its maturity date planter coulters to cut cleanly and minimizes varies depending on soil moisture and tempera- allelopathic effects from rye residue (64, 84). If ture. Tall and stemmy, rye immobilizes N as it using a herbicide, you might need a higher spray decomposes. The N tie-up varies directly with volume or added pressure for adequate coverage. the maturity of the rye.Mineralization of N is very slow, so don’t count on rye’s overwintered N Kill before it matures. Tilling under rye usually becoming available quickly. eliminates regrowth, unless the rye is less than 12 Killing rye early, while it’s still succulent, is inches tall (302, 351). Rye often is plowed or one way to minimize N tie-up and conserve soil disked in the Midwest when it’s about 20 inches moisture. But spring rains can be problematic tall (247). Incorporating the rye before it’s 18 in. with rye, especially before an N- high could decrease tie-up of demanding crop, such as corn. Rye is the best cool- soil N (302, 351). Even if plentiful moisture has- For best results when mow- tens the optimal kill period, you season cover crop for killing rye, wait until it has still might get too much rain in scavenging N, typically begun flowering. A long-day the following weeks and have plant, rye is encouraged to significant nitrate leaching, a carrying 25 to 50 lb. flower by 14 hours of daylight Maryland study showed (84).Soil N/A over to spring. and a temperature of at least 40 compaction also could be a F. A sickle bar mower can give problem if you’re mowing rye better results than a flail with heavy equipment. mower, which causes matting that can hinder Late killing of rye can deplete soil moisture and emergence of subsequent crops (89). could produce more residue than your tillage sys- Mow-kill works well in the South after rye tem can handle. For influencing corn yields in sheds pollen in late April (75). If soil moisture is humid climates, however, summer soil-water con- adequate, you can plant cotton three to five days servation by cover crop residues often is more after mowing rye when row cleaners are used in important than spring moisture depletion by grow- reduced-tillage systems. ing cover crops, Maryland studies showed (62, 64). Some farmers prefer to chop or mow rye by late boot stage, before it heads or flowers.“If rye Legume combo maintains yield. One way to gets away from you,you’d be better off baling it or offset yield reductions from rye’s immobilization harvesting it for seed,” cautions southern Illinois of N would be to increase your N application. organic grain farmer Jack Erisman (24). He often Here’s another option: Growing rye with a overwinters cattle in rye fields that precede soy- legume allows you to delay killing the covers by a beans. But he prefers that soil temperature be at few weeks and sustain yields, especially if the least 60 F before planting beans, which is too late legume is at least half the mix. This gives the for him to no-till beans into standing rye. legume more time to fix N (in some cases dou- “If rye is at least 24 inches tall, I control it with bling the N contribution) and rye more time to a rolling stalk chopper that thoroughly flattens scavenge a little more leachable N. Base the kill and crimps the rye stems,”says Pennsylvania veg- date on your area’s normal kill date for a pure etable grower Steve Groff. “That can sometimes stand of the legume (84). eliminate a burndown herbicide, depending on A legume/rye mix generally increases total dry the rye growth stage and next crop.” matter, compared with a pure rye stand. The A heavy duty rotavator set to only 2 inches higher residue level can conserve soil moisture. deep does a good job of tilling rye, says Rich de For best results, wait about 10 days after killing Wilde,Viroqua,Wis. (86).

RYE 69 Can’t delay a summer planting by a few weeks If weed suppression is an important objective while waiting for rye to flower? If early rye culti- when planting a rye/legume mixture, plant early vars aren’t available in your area and you’re in enough for the legume to establish well. Other- Zone 5 or colder, you could plow the rye and use wise,you’re probably better off with a pure stand. secondary tillage. Alternately, try a knockdown Overseeding may not be cost-effective before a herbicide and post-emergent herbicide or spot- crop such as field corn,however. A mix of rye and spraying for residual weed control. bigflower vetch (a quick-establishing, self-seed- Glyphosate provides a slow, yet effective, kill. ing, winter-annual legume that flowers and Paraquat kills more rapidly and would be better matures weeks ahead of hairy vetch) can sup- when spring moisture is limited (82). For quicker press weeds significantly more than rye alone, growth of a subsequent crop such as corn or soy- while also allowing higher N accumulations (85). beans, leave the residue upright after killing “Rye can provide the best and cleanest mulch (rather than flat). That hastens crop develop- you could want if it’s cut or baled in spring before ment—unless it’s a dry year—via warmer soil producing viable seed,” says Rich de Wilde (86). temperatures and a warmer seed zone, according Rye can become a volunteer weed if tilled to a three-year Ontario study (80,111). This rarely before it’s 8 inches high, however,or if seedheads influences overall crop yield, however, unless you start maturing before you kill it. Minimize plant too early and rye residue or low soil tem- regrowth by waiting until rye is at least 12 inches perature inhibits crop germination. high before incorporating or by mow-killing after flowering but before grain fill begins. Pest Management Thick stands ensure excellent weed sup- Insect pests rarely a problem. Rye can reduce pression. To extend rye’s weed-management insect pest problems in crop rotations, southern benefits, you can allow its allelopathic effects to research suggests (369). In a number of mid- persist longer by leaving killed Atlantic locations, Colorado pota- residue on the surface rather than Rye can effectively to beetles have been virtually incorporating it. Allelopathic absent in tomatoes no-till trans- effects usually taper off after suppress weeds by planted into a mix of rye/vetch/ about 30 days. After killing rye,it’s shading, competition crimson clover, perhaps because best to wait three to four weeks the beetles can’t navigate before planting small-seeded and allelopathy. through the residue (132). crops such as carrots or onions. If While insect infestations are strip tilling vegetables into rye, be aware that rye rarely serious with rye, as with any cereal grain seedlings have more allelopathic compounds crop occasional problems occur. If armyworms than more mature rye residue.Transplanted veg- have been a problem, for example, burning down etables, such as tomatoes, and larger-seeded rye before a corn crop could move the pests into species,especially legumes,are less susceptible to the corn. Purdue Extension entomologists note rye’s allelopathic effects (90). many northeastern Indiana corn farmers reported In an Ohio study, use of a mechanical under- this in 1997. Crop rotations and Integrated Pest cutter to sever roots when rye was at mid- to late Management can resolve most pest problems you bloom—and leaving residue intact on the soil sur- might encounter with rye. face (as whole plants)—increased weed suppression, compared with incorporation or mowing. Few diseases. Expect very few diseases when The broadleaf weed reduction was comparable to growing rye as a cover crop. A rye-based mulch that seen when sickle-bar mowing, and better can reduce diseases in some cropping systems. than flail-mowing or conventional tillage (70). No-till transplanting tomatoes into a mix of

70 MANAGING COVER CROPS PROFITABLY rye/vetch/crimson clover,for example,consistent- don’t expect dramatic soil improvement from a ly has been shown to delay the onset of early single stand’s growth. Left in a poorly draining blight in several locations in the Northeast (132). field too long,a rye cover could slow soil drainage The mulch presumably reduces soil splashing and warming even further,delaying crop planting. onto the leaves of the tomato plants. It’s also not a silver bullet for eliminating herbi- If you want the option of harvesting rye as a cides.Expect to deal with some late-season weeds grain crop, use of resistant varieties, crop rotation in subsequent crops (339). and plowing under crop residues can minimize rust, stem smut and anthracnose. COMPARATIVE NOTES

Other Options • Rye is more cold- and drought-tolerant than Quick to establish and easy to incorporate when wheat. succulent, rye can fill rotation gaps in reduced- • Oats and barley do better than rye in hot tillage, semi-permanent bed systems without weather. increasing pest concerns or delaying crop planti- • Rye is taller than wheat and tillers less. It can ngs, a California study showed (173). produce more dry matter than wheat and a Erol Maddox, a Hebron, Md. grower, takes few other cereals on poor, droughty soils but advantage of rye’s relatively slow decomposition is harder to burn down than wheat or triticale when double cropping. He likes transplanting (191, 302). spring cole crops into rye/vetch sod, chopping • Rye is a better soil renovator than oats (351), the cover mix at bloom stage and letting it lay but brassicas and sudangrass provide deeper until August, when he plants fall cole crops (199). soil penetration (371). Mature rye isn’t very palatable and provides • Brassicas generally contain more N than rye, poor-quality forage.It makes high quality hay or bal- scavenge N nearly as well and are less likely age at boot stage, however, or grain can be ground to tie up N because they decompose more and fed with other grains. Avoid feeding ergot- rapidly. infected grain because it may cause abortions. Rye can extend the grazing season in late fall SEED and early spring. It tolerates fall grazing or mowing with little effect on spring regrowth in many Cultivars. MERCED is a popular variety. AROO- areas (166). Growing a mixture of more palatable STOOK is very cold-tolerant. ALBION is nematicidal. cover crops (clovers, vetch or ryegrass) can ABRUZZI is the earliest Southern variety. ELBON is encourage regrowth even further by discouraging slightly later than ABRUZZI but both are earlier overgrazing (268). than RYMOR.

Management Cautions Seed sources. Widely available. Although rye’s extensive root system provides quick weed suppression and helps soil structure,

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

See charts, pp. 47 to 53, for ranking and management summary.

lthough typically grown as a cash grain, A wheat stand can take up 0.5 to 0.7 lb. of P2O5 winter wheat can provide most of the for each bushel of grain produced,but nearly two- A cover crop benefits of other cereal crops, thirds of it (20 to 25 pounds per acre for a 50- as well as a grazing option prior to spring tiller bushel wheat crop) is absorbed before boot stage. elongation. It’s less likely than barley or rye to Wheat also can take up 1.5 to 2 lb. K2O for each become a weed and is easier to kill. Wheat also bushel produced. About 90 percent of that is is slower to mature than some cereals, so there is taken up before wheat heads, and more than 80 no rush to incorporate it early in spring and risk percent of the K is recycled if the stems and compacting soil in wet conditions. leaves aren’t removed from the field at harvest. Whether grown as a cover crop or for grain, All the nutrients are recycled when wheat is winter wheat opens a rotation niche for under- managed as a cover crop, giving it a role in scav- seeding a legume (such as red clover or sweet- enging excess nitrogen. clover) for forage or nitrogen.It works well as part of a no-till or reduced-tillage crop rotation,and for “Cash and Cover” crop. Winter wheat provides weed control in potatoes grown with irrigation in a cash-grain option while also creating a niche in semiarid regions. a corn>soybean or similar rotation for a second cover crop, such as a winter annual legume. For BENEFITS example: • In the Cotton Belt, wheat and crimson clover Erosion control. Winter wheat can serve as an would be a good mix. overwintering cover crop for erosion control in • In Hardiness Zone 6 and parts of Zone 7, most of the continental U.S. plant hairy vetch after wheat harvest, giving the legume plenty of time to establish in fall. Vetch Nutrient catch crop. Wheat enhances cycling of growth in spring may provide most of the N nec- N, P and K. A heavy N feeder in spring, wheat essary for heavy feeders such as corn, or all of the takes up N relatively slowly in autumn.It adds up, N for sorghum, in areas northward to southern however. A September-seeded stand can absorb Illinois, where early spring warm-up allows time 40 lb. N/A by December, a Maryland study for development. showed (30). As an overwintering cover rather • In much of Zone 7,cowpeas would be a good than a grain crop, wheat wouldn’t need fall or choice after wheat harvest in early July or before spring fertilizer. planting winter wheat in fall (88).

72 MANAGING COVER CROPS PROFITABLY • 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. SearsElayne Wheat is a plentiful source of straw and stubble. WINTER WHEAT (Triticum aestivum) Although it generally produces less than rye or barley, the residue can be easier to manage and incorporate. Wheat’s fine root system also Biomass production and N uptake are fairly improves topsoil tilth. slow in autumn. Tillering resumes in late win- When selecting a locally adapted variety for use ter/early spring and N uptake increases quickly as a cover crop, you might not need premium during stem extension. seed. While a few cultivars, such as POCAHONTAS, Adequate but not excessive N is important dur- provide slightly more biomass in early growth ing wheat’s early growth stages (prior to stem stages, first-year data from a Maryland study of 25 growth) to ensure adequate tillering and root wheat cultivars showed no major differences in growth prior to winter dormancy. In low-fertility overall biomass production at maturity (66). If or light-textured soils, consider a mixed seeding weed control is important in your system,look for with a legume (60). Another alternative could be a regional cultivar that can produce early spring adding up to 50 pounds of starter N per acre,espe- growth.To scavenge N, select a variety with good cially on low-N soils if you’ll be killing the wheat in fall growth before winter dormancy. spring before a heavy-feeding crop such as potatoes and are relying on a thick,overwintering stand MANAGEMENT for weed control. See Wheat Offers High Value Weed Control, Too (p. 75). Too much N, however, Establishment & Fieldwork can produce rank, succulent plants that are Wheat prefers well-drained soils of medium tex- susceptible to winterkill, disease or lodging. ture and moderate fertility. It tolerates poorly A firm seedbed helps reduce winterkill of drained, heavier soils better than barley or oats, wheat. Minimize tillage in semiarid regions to but flooding can easily drown a wheat stand. Rye avoid pulverizing topsoil (297) and depleting soil may be a better choice for some poor soils. moisture (82).

WINTER WHEAT 73 Wheat Boosts Income and Soil Protection Wheat is an ideal fall cover crop that can use uncleaned or premium, cleaned seed. double as a cash crop, cotton farmer Max Disease or pests rarely have been a problem, Carter has found.“It’s easier to manage than he notes. rye, still leaves plenty of residue to keep “It’s a very easy system, with wheat always topsoil from washing away—and is an serving as a fall cover crop for us. It builds soil excellent double crop,”says Carter. and encourages helpful soil microorganisms. The southeastern Georgia farmer no-till drills It can be grazed, or we can burn some down winter wheat at 2 bushels per acre right after in March for planting early corn or peanuts cotton harvest, without any seedbed anytime from March to June,”he says. preparation.“It gives a good, thick stand,”he says. For a double crop before 2-bale-an-acre “We usually get wheat in by Thanksgiving, cotton, Carter irrigates the stand once in but as long as it’s planted by Christmas, I spring with a center pivot and harvests 45- know it’ll do fine,”he adds.After drilling to 60-bushel wheat by the end of May.“The wheat, Carter goes back and mows the cotton chopper on the rear of the combine puts the stalks to leave some field residue until the straw right back on the soil as an even blanket wheat establishes. and we’re back planting cotton on June 1.” He pays about 7 to 14 cents per pound for “It sure beats idling land and losing seed, depending on whether he chooses to topsoil.”

Winter annual use. Seed from late summer to Another possibility for Zone 7 and cooler: Plant early fall in Zone 3 to 7—a few weeks earlier than full-season soybeans into wheat cover crop a rye or wheat grain crop—and from fall residue, and plant a wheat cover crop after bean to early winter in Zone 8 and warmer. If your harvest (60). cover crop planting is delayed, consider sowing rye instead. Mixed seeding or nurse crop. At low to medi- Drill 60 to 120 lb./A (1 to 2 bushels) into a firm um rates (300), winter wheat is an excellent nurse 1 1 seedbed at a /2- to 1 /2-inch depth or broadcast 60 crop for frostseeding red clover (at 8 to 12 lb./A), to 160 lb./A (1 to 2.5 bushels) and disk lightly or or sweetclover (at 4 to 12 lb./A). In the Corn Belt, cultipack to cover. Plant at a high rate if seeding the legume usually would be sown in winter or late, when overseeding into soybeans at the leaf- before wheat’s vegetative growth resumes in yellowing stage,when planting into a dry seedbed spring. If you sow sweetclover in fall with winter or when you require a thick, weed-suppressing wheat, it could outgrow the wheat. If you want a stand. Seed at a low to medium rate when soil grain option, that could make harvest difficult. moisture is plentiful (51). After cotton harvest in Zone 8 and warmer, Spring annual use. Spotty overwintering of win- no-till drill 2 bushels of wheat per acre without ter wheat in your area? Or no time to fall-seed it? any seedbed preparation. With irrigation or in Although it’s not a common practice, you can humid regions, you could harvest 45- to 60- spring-seed winter wheat as a weed-suppressing bushel wheat, then double crop with soybeans, companion crop or early forage. It won’t have a cotton or another summer crop. See Wheat chance to vernalize (be exposed to extended cold Boosts Income and Soil Protection (above).You after germination), so it usually dies on its own also could overseed winter wheat prior to cot- within a few months,without setting seed.By sow- ton defoliation and harvesting (287). ing when field conditions permit in early spring,

74 MANAGING COVER CROPS PROFITABLY Wheat Offers High-Value Weed Control, Too Pairing a winter wheat cover crop with a September in Idaho.“In our area, growers can reduced herbicide program could provide deep rip in fall, disk and build the beds (hills), excellent weed control in potatoes grown then drill wheat directly into the beds,”she on light soils in irrigated, semiarid regions, says. Some starter N (50 to 60 lb./A) can help research in the inland Pacific Northwest the wheat establish. If indicated by soil testing, suggests.A SARE-funded study in the early P or K also would be fall-applied for the 1990s showed that winter wheat provided following potato crop. effective competition against annual The wheat usually does well and shows weeds that infest irrigated potato fields in good winter survival. Amount of spring rainfall Washington, Oregon and Idaho. However, and soil moisture and the wheat growth rate potato yield and quality reductions determine the optimal dates for killing wheat outweighed cost savings, that study’s and planting potatoes. economic analysis showed. Some years, you might plant into the wheat Banding herbicide over the row when and broadcast Roundup about a week later. planting potatoes improves the system’s Other years, if a wet spring delays potato effectiveness, subsequent research shows, says planting, you could kill wheat before it gets project coordinator Dr. Charlotte Eberlein at the out of hand (before the boot stage), then University of Idaho’s Aberdeen Research and wait for better potato-planting conditions. Extension Center. “In our initial study,we were Moisture management is important, effectively no-tilling potatoes into the Roundup- especially during dry springs, she says.“We killed wheat,”says Eberlein.“Now we kill the usually kill the wheat from early to mid May— cover crop and plant potatoes with a regular a week or two after planting potatoes.That’s potato planter, which rips the wheat out of the soon enough to maintain adequate moisture potato row.”A grower then can band a herbicide in the hills for potatoes to sprout.” mixture over the row and depend on the wheat An irrigation option ensures adequate soil mulch to control between-row weeds. moisture—for the wheat stand in fall or the “If you have sandy soil to start with and potato crop in spring, she adds.“You want a can kill winter wheat early enough to reduce good, competitive wheat stand and a vigorous water-management concerns for the potatoes, potato crop if you’re depending on a banded the system works well,”says Eberlein. herbicide mix and wheat mulch for weed “Winter rye would be a slightly better cover control,”says Eberlein.That combination crop for suppressing weeds in a system like gives competitive yields, she observes, based this,”she notes.“Volunteer rye, however, is a on research station trials. serious problem in wheat grown in the West, Full-scale on-farm studies and economic and wheat is a common rotation crop for analyses are next on the project agenda and potato growers in the Pacific Northwest.” could lead to greater use of winter wheat as She recommends drilling winter wheat at a cover crop for weed control, nutrient cycling 90 lb./A into a good seedbed, generally in mid- and other benefits.

within a couple months you could have a 6- to Early planting of spring wheat, with or 10-inch tall cover crop into which you can no-till without a legume companion, is an option, plant soybeans. You might not need a burndown especially if you have a longer rotation niche herbicide, either. available.

WINTER WHEAT 75 Field Management more of a problem the earlier wheat is planted in You needn’t spring fertilize a winter wheat stand fall, especially if you farm in a humid area. being grown as a cover crop rather than a grain Growing winter wheat could influence the crop. As with any overwintering small grain crop, buildup of pathogens and affect future small- however,you will want to ensure the wheat stand grain cash crops, however. Use of resistant vari- doesn’t adversely affect soil moisture or nutrient eties and other Integrated Pest Management availability for the following crop. practices can avoid many pest problems in wheat grown for grain.If wheat diseases or pests Killing are a major concern in your area, rye or barley Kill wheat with a grass herbicide in spring, or by might be a better choice as an overwintering plowing, disking or mowing before seedheads cover crop that provides a grain option, despite mature. their lower yield. There is no need to rush to kill wheat in spring as is sometimes Wheat is less likely Other Options required for rye. That’s one reason Choosing wheat as a small-grain vegetable grower Will Stevens, than barley or rye to cover crop offers the flexibility Shoreham, Vt., prefers wheat to become a weed, and in late spring or early summer to rye as a winter cover on his heavy, harvest a grain crop. Spring man- clay-loam soils.The wheat goes to is easier to kill. agement is essential for the grain seed slower and can provide more crop option.A good resource for leaf matter than an earlier killing grain production techniques, of rye would, he’s found.With rye, he has to disk used extensively in writing this chapter, is Best two to three weeks earlier in spring to incorpo- Management Practices for Wheat, listed under rate the biomass, which can be a problem in wet Recommended Resources (p. 163). conditions.“I only chisel plow wheat if it’s really rank,”he notes. Management Cautions Avoid grazing livestock in wheat stands suffering Pest Management from fungal diseases such as scab, which can Wheat is less likely than rye or barley to become produce substances toxic to livestock, especially a weed problem in a rotation, but is a little more nonruminants. susceptible than rye or oats to insects and disease. Managed as a cover crop, wheat rarely Seed sources. Widely available. poses an insect or disease risk. Diseases can be

76 MANAGING COVER CROPS PROFITABLY 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 low- fertility soils

Mix with: sorghum-Sudangrass hybrids, sunn hemp summer or too dry, cool See charts, pp. 47 to 53, for ranking cool-season annual and management summary.

uckwheat is the speedy short-season cover Hardiness Zone 5-6 (206).Buckwheat residue also crop. It establishes, blooms and reaches decomposes quickly, releasing nutrients to the Bmaturity in just 70 to 90 days. Then its next crop. residue breaks down quickly. Buckwheat suppresses weeds and attracts beneficial insects and Weed suppressor. Buckwheat’s strong weed- pollinators with its abundant blossoms. It is easy suppressing ability makes it ideal for smothering to kill, and reportedly extracts soil phosphorus warm-season annual weeds. It’s also planted after from soil better than most grain-type cover crops. intensive, weed-weakening tillage to crowd out Buckwheat thrives in cool, moist conditions perennials.A mix of tillage and successive dense but it is not frost tolerant. Even in the South, it is seedings of buckwheat can effectively suppress not grown as a winter annual. Buckwheat is not Canada thistle, sowthistle, creeping jenny, leafy particularly drought tolerant, and readily wilts spurge, Russian knapweed and perennial pepper- under hot, dry conditions. Its short growing sea- grass (206).While living buckwheat may have an son may allow it to avoid droughts, however. allelopathic weed-suppressing effect (291),its primary impact on weeds is through shading and BENEFITS competition.

Quick cover. Few cover crops establish as rapid- Phosphorus scavenger. Buckwheat is believed ly and as easily as buckwheat. Its rounded pyra- to be effective in taking up phosphorus and some mid-shaped seeds germinate in just three to five minor nutrients (possibly including calcium) that days. Leaves up to 3 inches wide can develop are otherwise unavailable to crops, then releasing within two weeks to create a relatively dense,soil- these nutrients to later crops as the residue shading canopy, though not as dense as corn or breaks down. The roots of the plants produce soybeans.Buckwheat typically produces only 2 to mild acids that free these nutrients from other 3 tons of dry matter per acre,but it does so quick- compounds. This effect aids in activating slowly—in just six to eight weeks in the mild, temper- releasing organic fertilizers, such as rock phos- ate fields of central Pennsylvania in USDA phate. Buckwheat’s dense, fibrous roots cluster in

BUCKWHEAT 77 sitize 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.

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, winter- hardy legumes wherever freezing temperatures are sure to kill the buckwheat.

MANAGEMENT

Marianne Sarrantonio Buckwheat prefers light to medium, well-drained BUCKWHEAT (Fagopyrum esculentum) 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 the top 10 inches of soil, providing an extensive cool, moist conditions, but is not frost-tolerant. It root surface area for nutrient uptake. is also not drought tolerant. Extreme afternoon heat will cause wilting, but plants bounce back Thrives in poor soils. Buckwheat performs bet- overnight. ter than cereal grains on low-fertility soils and soils with high levels of decaying organic matter. Establishment That’s why it was often the first crop planted on Plant buckwheat after all danger of frost. In cleared land during the settlement of woodland untilled, minimally tilled or clean-tilled soils, drill 1 1 areas and is still a good first crop for rejuvenating 50 to 60 lb./A at /2 to 1 /2 inches deep in 6 to 8- over-farmed soils. However, buckwheat does not inch rows. Use heavier rates for a quicker do well in compacted, droughty or excessively canopy. For a fast smother crop, broadcast up to wet soils. 96 lb./A (2 bu./A) onto a firm seedbed and incorporate with a harrow, tine weeder, disk or field Quick regrowth. Buckwheat will regrow after cultivator. Overall vigor is usually better in mowing if cut before it reaches 25 percent drilled seedings. As a nurse-crop for slow-grow- bloom. It also can be lightly tilled after the mid- ing, winter annual legumes planted in late sum- point of its long flowering period to reseed a sec- mer or fall, seed at one-quarter to one-third of ond crop. Some growers bring new land into the normal rate. production by raising three successive buck- Buckwheat compensates for lower seeding wheat crops this way. rates by developing more branches per plant and more seeds per blossom. However,skimping Soil conditioner. Buckwheat’s abundant, fine too much on seed makes stands more vulnerable roots leave topsoil loose and friable after only min- to early weed competition until the canopy fills imal tillage, making it a great mid-summer soil con- in. Using cleaned, bin-run or even birdseed-grade ditioner preceding fall crops in temperate areas. seed can lower establishment costs, but increases the risk of weeds. As denser stands mature, Nectar source. Buckwheat’s shallow white blos- stalks become spindly and are more likely to soms attract beneficial insects that attack or para- lodge from wind or heavy rain.

78 MANAGING COVER CROPS PROFITABLY Rotations Buckwheat can be double cropped for grain Buckwheat is used most commonly as a mid-sum- after harvesting early crops if planted by mid-July mer cover crop to suppress weeds and replace in northern states or by early August in the South. bare fallow. In the Northeast and Midwest, it is It requires a two-month period of relatively cool, often planted after harvest of early vegetable moist conditions to prevent blasting of the blos- crops, then followed by a fall vegetable, winter soms. There is modest demand for organic and grain,or cool-season cover crop. specially raised food-grade In many areas, it can be planted Buckwheat germinates buckwheat in domestic and following harvest of winter overseas markets.About 70,000 wheat or canola. and grows quickly, acres are grown in the U.S., In parts of California, buck- producing 2 to 3 tons with prices typically around wheat grows and flowers 10 cents/lb. Exporters usually between the killing of winter of dry matter in just specify variety, so investigate annual legume cover crops in 6 to 8 weeks. before planting buckwheat for spring and their re-establish- grain. ment in fall. Some California vineyard managers seed 3-foot strips of buck- Management Cautions wheat in row middles, alternating it and another To get optimal biomass while preventing buck- summer cover crop, such as sorghum-Sudangrass. wheat from becoming a weed in following crops, Buckwheat is sensitive to herbicide residues kill within 7 to 10 days after flowering begins, from previous crops, especially in no-till before the first seeds begin to harden and turn seedbeds. Residue from trifluralin and from tri- brown. Earliest maturing seed can shatter before azine and sulfonylurea herbicides have damaged plants finish blooming. Some seed may overwin- or killed buckwheat seedlings (57). When in ter in milder regions. doubt, sow and water a small test plot of the fast- Buckwheat can harbor insect pests including germinating seed to detect stunting or mortality. Lygus bugs, tarnished plant bugs and Pratylynchus penetrans root lesion nematodes (204). Pest Management Few pests or diseases bother buckwheat. Its most COMPARATIVE NOTES serious weed competitors are often small grains from preceding crops, which only add to the • Buckwheat has only about half the root mass cover crop biomass. Other grass weeds can be a as a percent of total biomass as small grains problem, especially in thin stands.Weeds also can (294). Its succulent stems break down increase after seed set and leaf drop. Diseases quickly, leaving soils loose and vulnerable include a leaf spot caused by the fungus to erosion, particularly after tillage. Plant a Ramularia and Rhizoctonia root rot. soil-holding crop as soon as possible. • Buckwheat is nearly three times as effective Other Options as barley in extracting phosphorus, and Plant buckwheat as an emergency cover crop to more than 10 times more effective than protect soil and suppress weeds when your main rye—the poorest P scavenger of the cereal crop fails or cannot be planted in time due to grains (294). unfavorable conditions. • As a cash crop, buckwheat uses only half as To assure its role as habitat for beneficial much soil moisture as soybeans (242). insects, allow buckwheat to flower for at least 20 days—the time needed for minute pirate bugs to Seed sources. Widely available. produce another generation.

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 summer annual irrigated See charts, pp. 47 to 53, for rank- year-round crop limited by cool temps. ing and management summary.

orghum-sudangrass hybrids are unrivaled for plants and nematodes. They are not frost adding organic matter to worn-out soils. tolerant, and should be planted after the soil SThese tall, fast-growing, heat-loving summer warms in spring or in summer at least six weeks annual grasses can smother weeds,suppress some before first frost. nematode species and penetrate compacted subsoil if mowed once.Seed cost is modest.Followed BENEFITS by a legume cover crop, sorghum-sudangrass hybrids are a top choice for renovating over- Biomass producer. Sorghum-sudangrass grows farmed or compacted fields. 5 to 12 feet tall with long,slender leaves,stalks up The hybrids are crosses between forage-type to one-half inch in diameter and aggressive root sorghums and sundangrass. Compared with corn, systems. These features combine to produce they have less leaf area,more secondary roots and ample biomass, usually about 4,000 to 5,000 lb. a waxier leaf surface, traits that help them with- DM/A. Up to 18,000 lb. DM/A has been measured stand drought (302). Like corn, they require good with multiple cuttings on fertile, well-watered fertility—and usually added nitrogen—for best soil. growth.Compared with sudangrass,these hybrids are taller, coarser and more productive. Subsoil aerator. Mowing whenever stalks reach Forage-type sorghum plants are larger, leafier 3 to 4 feet tall increases root mass five to eight and mature later than grain sorghum plants. times compared with unmowed stalks, and forces Compared with sorghum-sudangrass hybrids,they the roots to penetrate deeper. are shorter, less drought tolerant, and don’t In addition, tops grow back green and vegeta- regrow as well (292). Still, forage sorghums as tive until frost and tillering creates up to six new, well as most forms of sudangrass can be used in thicker stalks per plant. A single mowing on the same cover-cropping roles as sorghum-sudan- New York muck soils caused roots to burrow 10 grass hybrids. All sorghum- and sudangrass-related to 16 inches deep compared to 6 to 8 inches deep species produce compounds that inhibit certain for unmowed plants (224). The roots of mowed

80 MANAGING COVER CROPS PROFITABLY plants fractured subsoil compaction with worm- hole-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, sorghum- sudangrass 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 con-

centrations, comparable to those of some Marianne Sarrantonio synthetic herbicides (305). As early as five days SORGHUM-SUDANGRASS (Sorghum bicolor X after germination, roots begin secreting this alle- S. bicolor var. sudanese lochemical, which persists for weeks and has visible effects on lettuce seedlings even at 10 parts per million (362). systems, and weed and nematode suppression Sorghum-sudangrass hybrids suppress such can produce dramatic results. annual weeds as velvetleaf, large crabgrass, barn- On a low-producing muck field in New York yardgrass (97,245),green foxtail,smooth pigweed where onion yields had fallen to less than a third (146), common ragweed, redroot pigweed and of the local average, a single year of a dense plant- purslane (257).They also suppressed pine (171) ing of sorghum-sudangrass hybrid restored the and redbud tree seedlings in nursery tests (117). soil to a condition close to that of newly cleared The residual weed-killing effects of these allelo- land (174). chemicals increases when sorghum-sudangrass hybrids are treated with the herbicides sethoxy- Widely adapted. Sorghum-sudangrass hybrids dim, glyphosate or paraquat, in descending order can be grown throughout the U.S. wherever rain- of magnitude (109). fall is adequate and soil temperature reaches 65 F to 70 F at least two months before frost. Once Nematode and disease fighter. Planting established, they can withstand drought by going sorghum-sudangrass hybrids instead of a host nearly dormant. Sorghum-sudangrass hybrids crop is a great way to disrupt the life cycles of tolerate pH as high as 9.0, and are often used in many diseases, nematodes and other pests. For rotation with barley to reclaim alkaline soil (350). example, when sorghum-sudangrass or sorghum They tolerate pH as low as 5.0 (306). alone were no-tilled into endophyte-infected fescue pastures in Missouri that had received two Quick forage. Sorghum-sudangrass is prized as herbicide applications, the disease was controlled summer forage. It can provide quick cover to pre- nearly 100 percent. No-till reseeding with endo- vent weeds or erosion where legume forages have phyte-free fescue completed this cost-effective been winterkilled or flooded out. Use care renovation that significantly improved the rate of because these hybrids and other sorghums can gain of yearling steers (11). produce prussic acid poisoning in livestock. Grazing is riskiest when plants are young (up to Renews farmed-out soils. The combination of 24 inches tall), drought stressed or killed by frost. abundant biomass production, subsoiling root Toxicity danger varies between cultivars.

SORGHUM-SUNDANGRASS HYBRIDS 81 MANAGEMENT and keeps regrowth vegetative and less fibrous until frost. For mid-summer cuttings, leave at least Establishment 6 inches of stubble to ensure good regrowth and Plant sorghum-sudangrass when soils are warm continued weed suppression. Delayed planting— and moist, usually at least two weeks after the within seven weeks of frost—makes mowing prime corn-planting date for your area. It will tol- unnecessary and still allows for good growth erate low-fertility, moderate acidity and high alka- before winterkilling (223, 224, 302). linity, but prefers good fertility and near-neutral Disking while plants are still vegetative will pH (302). Standard biomass production usually speed decomposition. Make several passes with a requires 75 to 100 lb. N/A . heavy disk or combination tillage tool to handle With sufficient surface moisture, broadcast 40 the dense root masses (223).Sicklebar mowing or to 50 lb./A, or drill 35 to 40 lb./A as deep as 2 flail chopping before tillage will reduce the num- inches to reach moist soil.These rates provide a ber of field operations required to incorporate the quicker canopy to smother weeds than lower crop and speed decomposition. Sicklebars cut rates used for forage produc- more cleanly but leave the tion, but they require mowing These heat-loving plants stalks whole. Using a front- or grazing to prevent lodging. mounted flail chopper avoids Herbicide treatment or a pass are unrivaled for adding the problem of skips where with a mechanical weeder may organic matter to soils. tractor tires flatten the plants, be necessary if germination is putting them out of reach of a spotty or perennial weeds are rear-mounted chopper. a problem. New York on-farm tests show that a Any operations that decrease the residue size stale seedbed method—tilling,then retilling to kill shortens the period during which the decompos- the first flush of weeds just before planting— ing residue will tie up soil nitrogen and hinder provides effective weed control (224). early planted crops. Even when mowed, residue will become tough and slower to break down if Warm season mixtures. Plant sorghum-sudan- left on the surface. grass in cover crop mixtures with buckwheat or Flail chopping after frost or killing the cover with the legumes sesbania (Sesbania exaltata), crop with herbicide will create a suitable mulch sunnhemp (Crotolaria juncea), forage soybeans for no-till planting, preserving soil life and soil (Glycine max) or cowpeas (Vigna unguiculata). structure in non-compacted fields. Broadcast these large-seeded cover crops with the sorghum-sudangrass, then incorporate about 1 Pest Management inch deep.Fast-germinating buckwheat helps sup- Weeds. Use sorghum-sudangrass to help control press early weeds. Sorghum-sudangrass supports nutsedge infestations, suggests Cornell Extension the sprawling sesbania, forage soybeans and cow- IPM vegetable specialist John Mishanec. Allow peas. Sunnhemp has an upright habit, but could the nutsedge to grow until it’s about 4 to 5 inches compete well for light if matched with a tall, about mid-June in New York. Kill the nutsedge sorghum-sudangrass cultivar of a similar height. with herbicide, then plant the weed-smothering hybrid. Field Management Plants grow very tall (up to 12 feet),produce tons Beneficial habitat. Some related sorghum culti- of dry matter and become woody as they mature. vars harbor beneficial insects such as seven-spot- This can result in an unmanageable amount of ted lady beetles (Coccinella septempunctata) and tough residue that interferes with early planting lacewings (Chrysopa carnea) (350). the following spring (223). Mowing or grazing when stalks are 3 to 4 feet Nematodes. Sorghum-sudangrass hybrids and tall encourages tillering and deeper root growth, other sorghum-related crops and cultivars sup-

82 MANAGING COVER CROPS PROFITABLY press some species of nematodes. Specific culti- cover crop with a seed cost of $32.50/A was vars vary in their effectiveness on different races more effective than fumigation costing $300 to of nematodes. These high-biomass-producing $600/A. Further, the nematicidal effect continued crops have a general suppressive effect due to into the next season, while the conditions a year their organic matter contributions. But they also after fumigation seemed worse than before the produce natural nematicidal compounds that application. He reports that the sorghum-sudan- chemically suppress some nematodes, many grass cover crop also controls onion maggot, studies show. thrips and Botrytis leaf blight (174). Timing of cutting and tillage is very important to the effectiveness of nematode suppression. The Insect pests. Chinch bug (Blissus leucopterus), cover crop needs to be tilled before frost while it is sorghum midge (Contarinia sorghicola), corn leaf still green. Otherwise, the aphid (Rhopalosiphum maidis), nematicidal effect is lost. For These plants produce corn earworm (Heliothis zea), maximum suppression of soil- greenbugs (Schizaphis gram- borne diseases, cut or chopped chemicals that inhibit inum) and sorghum webworm Sudangrass must be well incor- certain weeds and (Celama sorghiella) sometimes porated immediately (248). attack sorghum-sudangrass hybrids. In an Oregon potato trial, nematodes. Early planting helps control the TRUDAN 8 sudangrass controlled first two pests, and may reduce Columbia root-knot nematodes (Meloidogoyne damage from webworms. Some cultivars and Chitwoodi), a serious pest of many vegetable hybrids are resistant to chinch bugs and some crops. Control extended throughout the zone of biotypes of greenbugs (302). In Georgia, some residue incorporation. The cover crop’s effect hybrids hosted corn leaf aphid,greenbug,southern prevented upward migration of the nematodes green stinkbugs (Nezara viridula) and leaffootted into the zone for six weeks,working as well as the bug (Leptoglossus phyllopus). nematicide ethoprop. Both treatments allowed infection later in the season (227). Crop Systems In the study, TRUDAN 8 sudangrass and the There are several strategies for reducing nitrogen sorghum-sudangrass hybrid cultivars SORDAN 79 tie-up from residue: and SS-222 all reduced populations of root-knot • Interplant a legume with the sorghum-sudan- nematodes. These cultivars are poor nematode grass hybrid. hosts and their leaves—not roots—have a nemati- • Plant a legume cover crop after the sorghum- cidal effect. TRUDAN 8 should be used if the crop sudangrass hybrid, in either late summer or will be grazed due to its lower potential for prus- the following spring. sic acid poisoning. The sorghum-sudangrass • Apply nitrogen fertilizer or some other N cultivars are useful if the cover crop is intended source at incorporation and leave the land for anti-nematicidal effects only (227). In other fallow for a few months when soil is not Oregon and Washington trials,the cover crop sup- frozen to allow decomposition of the residue. pression required supplemental chemical nemati- If you kill the cover crop early enough in fall, cide to produce profitable levels of U.S. No. 1 the residue will partially break down before cold potatoes (227). These same sudangrass and temperatures slow biological action (302). Where sorghum-sudangrass hybrid cultivars failed to possible, use sorghum-sudangrass ahead of later- show any significant nematicidal effects in a later planted crops to allow more time in spring for experiment in Wisconsin potato fields (198). residue to decompose. When faced with infestations of the nematodes Planting sorghum-sudangrass every third year Meloidogoyne incognita and M. arenaria, on New York potato and onion farms will rejuve- Oswego,N.Y.,onion grower Dan Dunsmoor found nate soil, suppress weeds and may suppress soil that a well-incorporated sorghum-sudangrass pathogens and nematodes. Working a legume into

SORGHUM-SUNDANGRASS HYBRIDS 83 Summer Covers Relieve Compaction A summer planting of sudangrass was the Heavy equipment, frequent tillage and lack best single-season cover crop for relieving of organic matter contribute to compaction soil compaction in vegetable fields, a problems for vegetable growers in the team of Cornell researchers found.Yellow Northeast, where frequent rains often force mustard, HUBAM annual white sweetclover growers into the fields when soils are wet. and perennial ryegrass also were effective Compacted soils slow root development, to some extent in the multi-year study.“But hinder nutrient uptake, stunt plants, delay sudangrass has proven the most promising maturity and can worsen pest and disease so far,”says project coordinator David Wolfe. problems. For example, the Cornell “It has shown the fastest root growth.” researchers found that slow-growing cabbages Sudangrass is particularly effective when direct-seeded into compacted soils were it is mowed once during the season,Wolfe vulnerable to flea beetle infestations. adds. Mowing strengthens its deep, Yellow mustard’s deep tap root may penetrating root system while the above- make it a solid challenger to sudangrass as ground biomass adds to soil organic matter. a compaction reliever. But it was sometimes Farmers and researchers have long difficult to establish in the test.“We still have known that alfalfa’s deep root system is a a lot to learn about how best to grow these great compaction-buster. But most vegetable crops and how best to fit them into rotations growers can’t afford to remove land from with vegetables,”Wolfe says. production for two to three years to Wolfe and his team assessed the cover crops’ grow it, notes Wolfe. Many also lack the effectiveness by measuring yields of subsequent equipment to subsoil their fields, which crops and conducting a host of soil quality is often only a temporary solution, at best. measurements, including infiltration rates, That’s why Wolfe geared his study to water-holding capacity,aggregate stability identify covers that can produce results and organic matter levels.They will follow in a single season. In the case of heat- up this research by examining the effects of loving sudangrass, it also may be possible compaction on pathogenic and beneficial to squeeze a spring or fall cash crop into microorganisms in the soil. the rotation while still growing the cover For more information, contact David Wolfe, during summer. (607) 255-5439, [email protected].

the rotation will further build soil health and add germination when alfalfa was no-till planted into nitrogen. Sorghum-sudangrass hybrids can pro- killed or living sorghum-sudangrass (110). vide needed soil structure benefits wherever In California, some table grape growers use intensive systems cause compaction and loss of sorghum-sudangrass to add organic matter and to soil organic matter reserves. See Summer Covers reduce the reflection of light and heat from the Relieve Compaction, above. soil, reducing sunburn to the grapes. Grown as a summer cover crop that is cut once and then suppressed or killed, sorghum-sudan- COMPARATIVE NOTES grass can reduce weeds in fall-planted alfalfa. Sorghum-sudangrass suppressed alfalfa root Sorghum-sudangrass hybrids can produce more growth significantly in a Virginia greenhouse organic matter per acre, and at a lower seed cost, study (109), but no effect was observed on alfalfa than any major cover crop grown in the U.S.

84 MANAGING COVER CROPS PROFITABLY Incorporated sorghum-sudangrass residue If you plan to graze the cover crop, select reduces N availability to young crops more than sorghum-sudangrass hybrids and related crops oat residue but less than wheat residue (319). with lower levels of dhurrin, the compound For suppressing root-knot nematodes in Idaho responsible for prussic acid poisoning. For potato fields, rapeseed has proven slightly more maximum weed control, choose types high in effective and more dependable than sorghum- sorgoleone, the root exudate that suppresses sudangrass hybrids (322). weeds. Sterile cultivars are best where escapes could be a problem, especially where crossing SEED with johnsongrass (Sorghum halpense) is possible. Cultivars. When comparing sorghum-sudangrass To extend weed suppressive effects into the cultivars, consider traits such as biomass yield second season, select a cultivar known for weed potential, tillering and regrowth ability, disease suppression and leave roots undisturbed when resistance, insect resistance (especially if green- the stalks are mowed or grazed (361). bugs are a problem) and tolerance to iron deficiency chlorosis. Seed sources. Widely available.

OVERVIEW OF LEGUME COVER CROPS

Commonly used legume cover crops include: N in spring.Winter-annual legumes must be plant- • Winter annuals, such as crimson clover, hairy ed earlier than cereal crops in order to survive the vetch, field peas, subterranean clover and winter in many regions. Depending on your cli- many others mate, spring management of legumes will often • Perennials like red clover, white clover and involve balancing early planting of the cash crop some medics with waiting to allow more biomass and N pro- • Biennials such as sweetclover duction. • Summer annuals (in colder climates, the win- Perennial or biennial legumes can fit many dif- ter annuals are often grown in the summer) ferent niches, as described in greater detail in the individual sections for those cover crops. Legume cover crops often are used to: Sometimes grown for a short period between • Fix atmospheric nitrogen (N) for use by subse- cash crops,these forage crops also can be used for quent crops more than one year and often are harvested for • Reduce or prevent erosion feed during this time. They can be established • Produce biomass and add organic matter to along with—or overseeded into—other crops the soil such as wheat or oats, then be left to grow after • Attract beneficial insects cash crop harvest and used as a forage. Here Legumes vary widely in their ability to prevent they are functioning more as a rotation crop than erosion, suppress weeds and add organic matter a cover crop, but as such provide many benefits to the soil. In general, legume cover crops do not including erosion and weed control, organic mat- scavenge N as well as grasses. Therefore, if you ter and N production. They also can break need a cover crop to take up excess nutrients weed, disease and insect cycles. after manure or fertilizer applications, a grass or a Summer-annual use of legume crops includes, mixture is usually a better choice. in colder climates, the use of the winter-annual Winter-annual legumes, while established in crops listed above, as well as warm-season the fall,usually produce most of their biomass and legumes such as cowpeas. Grown as summer

SORGHUM-SUNDANGRASS HYBRIDS 85 annuals, these crops produce N and provide contained in legume residues are usually released ground cover for weed and erosion control, as faster than from grasses.Weed control by legume well as other benefits of growing cover crops. residues may not last as long as for an equivalent Establishment and management varies widely amount of grass residue. Legumes do not increase depending on climate, cropping system and the soil organic matter as much as grasses. legume itself. These topics will be covered in the Mixtures of legume and grass cover crops com- individual sections for each legume. bine the benefits of both, including biomass pro- Legumes are generally lower in carbon and duction, N scavenging and additions to the higher in nitrogen than grasses. This lower C:N system,as well as weed and erosion control.Some ratio results in faster breakdown of legume cover crop mixtures are described in the individ- residues. Therefore, the N and other nutrients ual cover crop sections.

GRASS/LEGUME MIXTURES EXPAND POSSIBILITIES

ixtures of two or more cover crops are Using drought-tolerant plants in a perennial often more effective than planting a mix builds in persistence for dry years. Using a Msingle species.Cover crop mixtures offer number of cover crops with “hard seed”that takes the best of both worlds,combining the benefits of many months to germinate also improves cover- grasses and legumes,or using the different growth age over a broader range of conditions. characteristics of several species to fit your needs. Mixing cultivars of a single species with varied You can use cover crop mixtures to improve: maturity dates and growth habits maintains opti- • Winter survival mum benefits for a longer time. Orchardists in • Ground cover California mix subclovers to keep weeds at bay • Use of solar energy all season. One cultivar comes on early, then dies • Biomass and N production back as two later cultivars—one tall and one • Weed control short—come on strong. Because they reseed • Duration of active growing period themselves,the cooperative trio persists year after • Range of beneficial insects attracted year. • Tolerance of adverse conditions Sometimes you don’t know how much N may • Forage options be left after cash crop harvest. Do you need a • Response to variable soil traits grass to scavenge leftover N, or a legume to pro- Possible disadvantages of cover crop mixtures vide fixed N? A grass/legume cover crop mixture may include: adjusts to the amount of available soil N: If there • Higher seed cost is a lot of N, the grass dominates; if there is not • Too much residue much available soil N, the legume will tend to • More complicated management dominate a mixture. In either case, you get the • Difficult to seed combined benefit of N scavenging by the grass Crop mixtures can reduce risk in cropping sys- cover crop and N additions from the legume tems because each crop in the mix may respond cover crop. differently to soil, pest and weather conditions. In Mixing low-growing and taller crops, or fast- forage or grazing systems, for example, a mix of starting grasses and slow-developing legumes, rye, wheat and barley is more nutritious, can be usually provides better erosion control because grazed over a longer period of time and is less more of the ground is covered. The vegetation likely to be devastated by a single disease. intercepts more raindrops before they can dis-

86 MANAGING COVER CROPS PROFITABLY lodge soil particles. Sunlight is used more effi- • The best time to kill one crop may not be the ciently because light that passes through the tall best for another crop, so a compromise date crop is captured by the low-growing crop. may be used. Adding grasses to a fall-seeded legume • If you use herbicides, your choices may be lim- improves soil coverage over winter and increases ited when you plant a mixture of legumes and the root mass to stabilize topsoil. A viny crop like nonlegumes. vetch will climb a grass, so it can get more light • Sometimes you can end up with more residue and fix more N, or so it can be harvested more than your equipment can handle. easily for seed. A faster-growing crop serves as a The benefits of a mixture will usually outweigh nurse crop for a slow-growing crop, while cover- these disadvantages,but you need to be prepared to ing the ground quickly for erosion control. The manage the mixture carefully to prevent problems. possibilities are endless! Each cover crop chapter gives examples of spe- Mixtures can complicate management, how- cific mixtures that have been tested and work well. ever. For example: Try some of the proven cover crop mixtures, and • They may cost more to seed. Seeding rates for create your own tailor-made mixtures. Remember each component of the mix are usually lower that adding another crop increases the diversity on than for sole-crop plantings, but the total seed your farm, and is likely to increase the many proven cost may still be more. 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 summer annual winter annual See charts, p. 47 to 53, for ranking and management summary.

fast-growing summer annual, berseem Corn Belt rotations. Berseem clover draws down clover can produce up to 8 tons of forage soil N early in its cycle. Once soil reserves are Aunder irrigation. It’s a heavy N producer used up, it can fix 100 to 200 lb. N/A or more. It and the least winter hardy of all true annual establishes well with an oat nurse crop, making it clovers.This makes it an ideal winterkilled cover an excellent cover for small grain>corn>soybean before corn or other nitrogen-demanding crops in rotations in the Midwest.

BERSEEM CLOVER 87 In Iowa, the cultivar BIGBEE compares favorably respectively. With irrigation, berseem clover with alfalfa in its regrowth following small grain topped 19 other legumes at the same site with a harvest,its feed value and its tolerance to drought mean yield of 5,500 lb. DM/A. and excess moisture (119). As a winter annual in California, irrigation usually is needed to allow Smother crop. Planted with oats or annual berseem to achieve its full potential. Its peak ryegrass, berseem clover suppresses weeds well growth period during the West Coast’s rainy sea- during establishment and regrowth after oat son and its highly efficient water use compare harvest. favorably to alfalfa as a high-producing forage and green manure. Alfalfa has its peak growth during Companion crop. Planted with oat, the two dry summer periods (127). crops can be harvested together as silage, haylage or hay, depending on the crop’s development BENEFITS stage. Berseem/oat haylage has very high feed quality if cut at oats’boot stage (120).Dry seasons Green manure. Berseem clover is the fertility favor development of an oat grain crop, after foundation of agriculture in the Nile Delta, and which berseem clover can be cut one, two or has nourished soils in the Mediterranean region three times in the Midwest. for millennia. MULTICUT berseem clover averaged 280 lb. N/A in a six-year trial in California with Quick growing. At 60 F, berseem clover will six cuttings per year (127), and grew faster than be ready to cut about 60 days after planting. BIGBEE in one Iowa report (118). Berseem is less prone to possible N leaching if grown to maturi- Legume nurse crop. Because of its quick ty without cutting, when it produces 100 to 125 germination (seven days), quick growth and lb. N/A. Top N fixation occurs when soils have winterkilling tendency, berseem clover can be less than 150 lb. N/A (127). A single cutting can used as a nurse crop for alfalfa. yield 50 to 100 lb. topgrowth N/A. Berseem’s dry matter N concentration is about 2.5 percent Seed crop. Berseem produces up to 1,000 lb. (127). seed/A if it is left to mature. Only BIGBEE berseem clover has hard seed that allows natural self- Biomass. Berseem clover produced the most reseeding, and it reseeds too late for timely plant- biomass (6,550 lb./A) of five winter annual ing of most summer crops (77). legumes in a two-year Louisiana test,and came in second to arrowleaf clover (Trifolium vesiculo- Grazing and forage crop. At 18 to 28 percent sum) in N, accumulating 190 lb. N/A to protein, young berseem clover is comparable to arrowleaf’s 203 lb. N/A. Also tested were TIBBEE or better than crimson clover or alfalfa as feed. crimson clover WOOGENELLUP subterraneum No cases of bloat from grazing berseem clover clover and WOODFORD bigflower have been reported (121, 225). vetch. All but arrowleaf clover MULTICUT berseem Forage quality remains accept- were able to set seed by May 13 able until the onset of seed pro- and regrow in the fall,despite the clover averaged 280 duction. BIGBEE berseem clover herbicides used to suppress lb. N/A in a six-year and TIBBEE crimson produce them in spring and to control more fall and winter growth than weeds during summer (23). California trial. do other winter annual clovers in In recent Alberta legume trials, the South. BIGBEE continues pro- berseem clover averaged 3,750 lb. dry matter/A ducing longer into the spring than other over three years at a site where hairy vetch and legumes, extending cuttings into late May or field peas produced 5,300 lb. and 4,160 lb., early June in Mississippi (179).

88 MANAGING COVER CROPS PROFITABLY 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 full- revolution of the metering device. That season sunshine of the family’s market garden allows him to open the feed gates of the between tomatoes or beet rows (134).

MANAGEMENT Montana trials set the optimum seeding rate at about 8 lb./A drilled in 12-inch rows, with a high- Establishment er rate in narrower rows where herbicides are not Berseem prefers slightly alkaline loam and silty used to control weeds (364). soils but grows in all soil types except sands. Soil phosphorus can limit berseem clover growth. Midwest. Seed after April 15 to avoid crop loss Fertilize with 60 to 100 lb. P2O5/A if soil tests due to a late frost.Berseem frostseeded at 15 lb./A below 20 ppm (127). Boron also may limit yields well in the upper Midwest. In southern growth, so test soil to maintain levels (225). Michigan, frostseeded berseem clover produced Berseem tolerates saline conditions better than 1.5 T dry matter/A and 85 lb. N/A (308), but frost alfalfa and red clover (91). Use R-type inoculant risk is significant (124). suitable for berseem clover and crimson clovers. Iowa tests over four years showed that inter- Broadcast or drill berseem seed alone or with seeded berseem and oats averaged 76 percent spring grains onto a firm, well-prepared seedbed more dry matter (ranging from 19 to 150 percent) 1 or closely cropped sod so that it is /4-inch deep than oats alone.Underseeding berseem clover did with a light soil covering. To improve seed-soil not significantly reduce oat yields in another Iowa contact and to maintain seed-zone moisture, study.Seed early- to mid-April in Iowa (122). cultipack or roll soil before and after broadcast When seeding a mixture, harvest goals affect seeding (127). Dry, loose soil will suppress variety selection and seeding rates,Iowa research- germination. ers have found. If establishment of an optimum Recommended seeding rates are 8 to 12 lb./A berseem clover stand for green manure is most drilled or 15 to 20 lb./A broadcast.Excessive rates important, oat or other small grain crop seeded at will create an overly thick stand that prevents about 1 bushel per acre will protect the young tillering and spreading of the root crowns. clover and help to break the soil crust. If early

BERSEEM CLOVER 89 season 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).

Field Management 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

Marianne Sarrantonio encourage growth of up to 4 T/A. Keep stubble BERSEEM CLOVER (Trifolium alexandrinum) height at least 3 to 4 inches tall, because plants regrow from lower stem branches. To maximize dry matter production, cut as forage before green manuring is the goal, seed a soon as basal bud regrowth reaches 2 inches mixture of 4 bu.oats and 15 lb.berseem/A.If bio- (127). At the latest, clip before early flowering mass quantity is foremost, use a short-stalked, stage or plants will not regrow. Berseem long-season oat. If oat grain production is clover responds best when field traffic is primary, keep oat seeding rate the same, but minimized (119). select a short-season, tall variety to reduce the Mowed berseem clover left in the field as green likelihood of berseem clover interfering with manure can hinder regrowth of the legume from grain harvest (119). its lower stems. To lessen this problem, flail or Berseem clover also can be a late-summer crop. sickle-bar mow then rake or fluff with a tedder at Planted in mid-August in the Corn Belt, it should intervals until regrowth commences (124). grow about 15 inches before frost,provide winter Remember that berseem clover has a tap root erosion protection and break down quickly in and shallow 6- to 8-inch feeder root system (119). spring to deliver N from its topgrowth and roots. In thin plantings or well-drained soils, it can be You can overseed berseem clover into standing susceptible to drought, a trait that could trigger small-grain crops, a method that has worked well mowing, grazing or killing earlier than originally in a series of on-farm tests in Iowa (118).Plant the planned (143). berseem as late as three weeks after the grain Abundant soil N will restrict N fixation by crop germinates or after the tillering stage of win- berseem clover, but moderate amounts up to 150 ter-seeded small grains. Use a heavy seeding rate lb. N/A did not limit annual fixation in north cen- to compensate for reduced seed-soil contact. tral California. Researchers explain that berseem Frostseeding in late winter into winter wheat has clover draws heavily on soil N during early not worked in several attempts in Pennsylvania growth. When soil N was depleted in this test, (302) and Iowa (124). berseem began fixing N rapidly until it produced seed and died (368). Southeast. Fall planting in mild regions provides Berseem made its N contribution to soil in the effective weed control as well as N and organic final third of its cutting cycle—regardless of initial matter for a spring crop. Seed Aug. 25 to Oct. 15 soil N availability—in all six years of the study. in Mississippi or up to Dec.1 in Florida.For a cool- Nitrogen fixation was closely correlated to a drop

90 MANAGING COVER CROPS PROFITABLY in water-use efficiency in the trial. After producing In a northern Mississippi mechanical control from 400 to 640 lb. of dry matter per acre-inch of study, BIGBEE berseem clover added the most dry water in the first four cuttings,production dropped matter after mid-April compared to hairy vetch, to 300 lb. DM/A-in. for the final two cuttings (368). MT.BARKER subterranean clover and TIBBEE crimson clover. Berseem and hairy vetch remained Small grain companion. Underseeded berseem vegetative until mid-May, but by early May, ber- clover provided about 1.2 T forage dry matter/A seem clover and crimson had a considerable after oat harvest in Iowa, worth about $75/A as amount of stems laying down (79). commercial livestock feed. Removing the forage Rolling with 4-inch rollers killed less berseem decreases the soil-saving ground cover and N con- clover than hairy vetch or crimson when the tribution (122), trading soil and legumes had more than 10 N benefits for attractive near- The least winter hardy of inches of stem laying on the term income. ground. Kill rate was more In the Midwest, greenchop the true annual clovers, than 80 percent for the latter an oat/berseem clover mixture berseem can be planted two crops, but only 53 per- when oat is at the pre-boot cent for berseem clover. stage to avoid berseem clover with oats in the Corn Belt Without an application of going to seed early and, there- and produce abundant N atrazine two weeks prior to fore, not producing maximum either flail mowing or rolling nitrogen. Oats have high forage before winterkilling. with coulters,the mechanical N values at this stage. Monitor controls failed to kill more carefully during warm periods to avoid nitrogen tox- than 64 percent of the berseem clover until early icity (299). May, when flailing achieved 93-percent control. A Montana study found that spring plantings of Atrazine alone reduced the stand by 68 percent in berseem clover will produce the most legume dry early April,72 percent in mid-April and 88 percent matter and N if clear seeded. If, however,you wish to in early May (79). maximize total dry matter and protein, seeding with oats is recommended. The oat nurse crop suppressed Pest Management weeds well and increased total dry matter production Avoid direct seeding small-seeded vegetables into by 50 to 100 percent regardless of whether plots fields where you have incorporated berseem were cut two,three or four times (356). clover within the past month. Berseem clover, crimson clover and hairy vetch residue incorporat- Killing ed directly into the seed zone may suppress germi- Berseem dies when exposed to temperatures be- nation and seedling development of onion, carrot low 20 F for several days, making winterkill a virtu- and tomato, based on interaction of extracts from al certainty in Zone 7 and colder. This eliminates these legumes and the seeds in lab tests (26). the need for herbicides or mechanical killing after Lygus bugs have been a serious problem in a cold winter, and hastens delivery of nutrients to California seed production, and virus outbreaks the soil. can cause serious damage during wet springs To kill berseem clover ahead of fall-planted where berseem grows as a winter annual.Where crops,wait for it to die after blooming,use multiple virus is a concern, use JOE BURTON, a resistant diskings or apply herbicides.In mild areas,berseem cultivar. BIGBEE is susceptible to crown rot and clover grows vigorously through late spring. BIGBEE other root diseases common to forage legume berseem clover remained vegetative until early May species (127). or later in an experiment at a northern Mississippi Berseem, like other clovers, shows little resis- (Zone 7) site. Until it reaches full bloom, it will tance to root-knot nematode (Meloidogyne require either tillage or a combination of herbi- spp.). It seems to be particularly favored by cides and mechanical controls to kill it. rabbits (302).

BERSEEM CLOVER 91 Nodulation: Match Inoculant to Maximize N With the help of nitrogen-fixing bacteria, soil. Other environmental factors such as heat legume cover crops can supply some or all and moisture play a big role, as well. Fueling N of the N needed by succeeding crops. This fixation is an expensive proposition for the nitrogen-producing team can’t do the job right legume host, which may contribute up to 20 unless you carefully match the correct percent of its carbohydrate production to the bacterial inoculant with your legume cover root-dwelling bacteria. If the legume can take crop species. up free N from the soil, it won’t put as much Like other plants, legumes need nitrogen to energy into producing nodules and feeding grow. They can take it from the soil if enough bacteria to fix nitrogen from the air. is present in forms they can use. Legume roots Perennial legumes fix N during any time of also seek out specific strains of soil-dwelling active growth. In annual legumes, N fixation bacteria that can “fix”nitrogen gas from the air peaks at flowering.With seed formation, it for use by the plant.While many kinds of ceases and the nodules slough from the roots. bacteria compete for space on legume roots, Rhizobia return to the soil environment to the root tissues will only begin this symbiotic await their next encounter with legume roots. N-fixing process when they encounter a These bacteria remain viable in the soil for specific species of rhizobium bacteria. Only three to five years, but often at too low a level particular strains of rhizobia provide optimum to provide optimum N-fixation when legumes N production for each group of legumes. return to the field. When the root hairs find an acceptable If legume roots don’t encounter their ideal bacterial match, they encircle the bacteria to bacterial match, they work with the best strains create a nodule. These variously shaped lumps they can find. They just don’t work as on the root surfaces range in size from a BB efficiently together and they produce less N. pellet to a kernel of corn. Their pinkish Inoculating seeds with the correct strain before interiors are the visible sign that nitrogen planting is inexpensive insurance to make sure fixation is at work. legumes perform up to their genetic potential. Nitrogen gas (N2) from air in the spaces Clover inoculum, for example, costs just 6 cents between soil particles enters the nodule.The per pound of seed treated, plus about 12 cents bacteria contribute an enzyme that helps per pound for an enhanced sticker that buffers convert the gas to ammonia (NH3).The plant and feeds the seedling (194). uses this form of N to make amino acids, the While they are alive, legumes release little building blocks for proteins. In return, the host or no nitrogen to the soil. The N in their roots, legume supplies the bacteria with stalks, leaves and seeds becomes available carbohydrates to fuel the N-fixation process. when the plants die naturally or are killed The rate of N fixation is determined largely by tillage, mowing or herbicide. This plant by the genetic potential of the legume species material becomes food for microbes, worms, and by the amount of plant-available N in the insects and other decomposers.

Crop Systems An added benefit is that it requires no tillage or Flexible oats booster. In the Corn Belt,berseem herbicide to kill it in spring (122). Plant 4 bu. oats clover seeded with can helps diversify corn>soy- with 12 lb. berseem/A. bean rotations,breaking pest cycles and providing In a four-year Iowa study, planting berseem some combination of grain and/or forage harvest, clover with oats increased net profit by $39/A erosion control and N to the following corn crop. compared with oats alone.The clover was baled

92 MANAGING COVER CROPS PROFITABLY Microorganisms mineralize, or convert, the Re-inoculate if you don’t plant the seed within complex “organic”forms of nitrogen in the 48 hours. Mix small quantities in a five-gallon plant material into inorganic ammonium bucket or tub, either by hand or using a drill and nitrate forms, once again making the equipped with a paint-mixer attachment. For N available to plants. How quickly the larger quantities, use special inoculant mixing mineralization of N occurs is determined by hoppers or a cement mixer without baffles. a host of environmental and chemical factors. On-farm use of commercial sticker/inoculant These will affect how much of that legume products has produced more consistent results N is available to the next crop or has the than pelleting methods applied by seed potential to leach from the soil. companies (357). Gum arabic stickers with For more information about mineralization sugars and liming agents boost the chances and how much you can reduce your N for optimum nodulation over water-applied fertilizer rate for crops following legumes, inoculant alone. Pre-inoculated (“rhizo-coated”) see How Much N? (p. 22). seed weighs about one-third more than raw To get the most from your legume/bacteria seed, so increase seeding rates accordingly. combination: Commercial sticker/inoculant products add • Choose appropriate legume species for about 5 percent to seed weight. your climate, soils and cropping system. Check nodulation as the plants approach Also, consider the amount of N it can bloom stage. Push a spade in the soil about 6 deliver when you will need it. inches below the plant. Carefully lift the plant • Match inoculant to the species of legume and soil, gently exposing roots and nodules. you are growing. See Chart 3B, Planting (Yanking roots from the soil usually strips off (p. 51) to determine the best inoculant to nodules).Wash gently in a bucket of water to use. see the extent of nodulation. Slice open nodules. • Coat seed with the inoculant just before A pink or reddish interior indicates active N- planting. Use milk, weak sugar water or a fixation. Remember, an overabundance of soil commercial sticking agent to help the nitrogen from fertilizer, manure or compost material stick to the seeds. Use only fresh can reduce nodulation. inoculant (check the package’s expiration For more information about nodulation, date), and do not expose packages or see two books by Marianne Sarrantonio: inoculated seed to excessive heat or direct Northeast Cover Crop Handbook (1994, sunlight. Rodale Institute, Kutztown, Pa. 19530) Mix the sticker with non-chlorinated water pp. 35-49, and Methodologies for Screening and add the inoculant to create a slurry,then Soil-Improving Legumes (1991, Rodale thoroughly coat seeds. Seed should be dry Institute Research Center) pp. 63-67. enough to plant within half an hour.

for forage and the underseeded oats were har- cent and reduced weed competition compared vested for grain. Not calculated in the benefit with a year of oats alone (122). were the 40 to 60 lb. N/A provided to the follow- Pure berseem clover regrowth averaged 1.2 T ing corn or other soil-improvement benefits.The dry matter/A,which can be used as forage or green oats/berseem mix produced 70 percent more bio- manure. These options could help oats become an mass,increased subsequent corn yields by 10 per- economically viable crop for Midwest crop/live-

BERSEEM CLOVER 93 stock farms in an era of decreasing government • Bee-friendy because its white or ivory blos- payments for corn and soybeans (122, 123). soms have no tripping mechanism. • Because of its short roots, berseem clover does Wheat companion. Berseem was one of six not utilize phosphorus to the depth that legume intercrops that improved productivity mature, perennial alfalfa does. and profit of wheat and barley crops in low-N • Winterkilled berseem allows for earlier spring soils under irrigated conditions in northwestern planting than winter-hardy annuals. As a dead Mexico. All of the legumes (including common organic mulch, it poses no moisture depletion and hairy vetch, crimson clover,New Zealand and risk, but may slow soil warming and drying Ladino white clover, and fava beans) provided compared to erosion-prone bare fallow. multiple benefits without decreasing grain yield of 15 to 60 bu./A on the heavy clay soil. SEED Wheat and legumes were planted at normal monoculture rates with wheat in double rows Cultivars. BIGBEE berseem clover was selected about 8 inches apart atop 30-inch beds, and from other traditional cultivars for its cold-toler- legumes in the furrows. In a second, related ance, which is similar to crimson clover. Some of experiment, researchers found they could more the strong winter production tendency found in than double total wheat productivity (grain and non-winter hardy berseem clover was sacrificed total dry matter) by interplanting 24-inch strips of to obtain BIGBEE’S winter hardiness (127). Mature berseem clover or hairy vetch with double rows BIGBEE plants hold their seeds well and produce of wheat 8 inches apart. Control plots showed adequate hard seed for reseeding. Other berseem wheat planted at a greater density did not clover cultivars have less hard seed and will not increase yield (290). dependably reseed (225). California tests show MULTICUT berseem clover Vegetable overseeding. Berseem can be over- produces 20 to 25 percent more dry matter than seeded into spring vegetables in northern BIGBEE. It has greater N-fixing ability, blooms later, climates where it thrives at moderate tempera- and has a longer growing period than other tures and moisture. Berseem is varieties, but is not as cold well suited to a “mow and Mow strips of berseem tolerant as BIGBEE (127). blow” system where strips of In California, BIGBEE begins green manure are chopped and between vegetable rows to flower in mid-May, about transferred to adjacent crop and blow the clippings two weeks ahead of MULTICUT. strips as a green manure and MULTICUT grows faster and pro- mulch (302). around the plants for duces more dry matter in Cali- Boost the N plow-down mulch. fornia conditions, averaging potential of old pastures or about 1.6 T/A more in a six-year winter-killed alfalfa by no-tilling study. When the five or six or interseeding berseem clover. Or, broadcast cuttings per year were clipped and removed, seed then incorporate with light harrowing. MULTICUT was about 6 inches taller at each clipping than other varieties (368). In Montana tests, BIGBEE COMPARATIVE NOTES out-yielded MULTICUT in eight of 13 locations (314).

Berseem clover is: Seed sources. Albert Lea, Cal/West, Harmony, • Similar to alfalfa in drought tolerance, but L.L. Olds, Peaceful Valley, Pennington, Rupp, some cultivars can tolerate more soil moisture Sexauer, Welter and Wolf River. (Cal/West and than alfalfa or sweet clover Welter have MULTICUT). See Seed Suppliers • Similar in seed size to crimson clover (p. 166).

94 MANAGING COVER CROPS PROFITABLY 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 See charts, pp. 47 to 53, for ranking and management summary.

owpeas are the most productive heat- block out weeds.Thick stands that grow well can adapted legume used agronomically in the out-compete bermudagrass where it does not pro- CU.S. (221). They thrive in hot, moist zones duce seed and has been plowed down before where corn flourishes, but require more heat for cowpea planting (211). TROY cowpeas produced optimum growth (211). Cowpea varieties have di- an average of about 5,100 lb. dry matter/A in a verse growth habits. Some are short, upright bush two-year Nebraska screening of cover crops. types.Taller, viny types are more vigorous and bet- Soybeans averaged about 7,800 lb. DM/A in ter suited for use as cover crops. Cowpeas protect comparison plots (271).Typical biomass produc- soil from erosion,smother weeds and produce 100 tion is 3,000 to 4,000 lb./A (302). to 150 lb. N/A. Dense residue helps to improve soil texture but breaks down fairly quickly. Excellent Quick green manure. Cowpeas nodulate drought resistance combined with good tolerance profusely, producing an average of about 130 lb. of heat, low fertility and a range of soils make cow- N/A in the East, and 200 lb. N/A in California. peas viable throughout the temperate U.S. where Properly inoculated in nitrogen deficient soils, summers are warm or hot but frequently dry. cowpeas can produce more than 300 lb.N/A (91). Cowpeas make an excellent N source ahead of Plowdown often comes 60 to 90 days after plant- fall-planted crops and attract many beneficial ing in California (221). Higher moisture and more insects that prey on pests. Used in California in soil N favor vegetative growth rather than seed vegetable systems and sometimes in tree crops, production. Unlike many other grain legumes, cowpeas also can be used on poor land as part of cowpeas can leave a net gain of nitrogen in the a soil-building cover crop sequence. field even if seed is harvested (302).

BENEFITS IPM insectary crop. Cowpeas have “extrafloral nectaries”—nectar-release sites on petioles and Weed-smothering biomass. Drilled or broad- leaflets—that attract beneficial insects, including cast cowpea plantings quickly shade the soil to many types of wasps,honeybees,lady beetles,ants

COWPEAS 95 and soft-winged flower beetles (351). Plants have all viny cultivars noted for superior resistance to long, slender round pods often borne on bare rodent damage (258). IRON AND CLAY, a mixture of petioles above the leaf canopy. two formerly separate cultivars widely used in the Intercropping cotton with cowpeas in India Southeast, combines semi-bushy and viny plants increased levels of predatory ladybugs and para- and resistance to rootknot nematodes and wilt. sitism of bollworms by beneficial wasps. Inter- Most of the 50-plus commercial cowpea culti- cropping with soybeans also increased parasitism vars are horticultural. These include “crowder of the bollworms compared with plots inter- peas” (seeds are crowded into pods), grown cropped with onions or cotton without an inter- throughout the temperate Southeast for fresh pro- crop. No effects on overall aphid, leafhopper or cessing,and “blackeye peas,”grown for dry seed in bollworm populations were observed (351). California. Use leafy,prostrate cultivars for the best erosion Companion crop. Thanks to its moderate shade prevention in a solid planting. Cultivars vary sig- tolerance and attractiveness to beneficial insects, nificantly in response to environmental condi- cowpeas find a place in summer cover crop mix- tions. Enormous genetic diversity in more than tures in orchards and vineyards in the more temper- 7,000 cultivars (91) throughout West Africa,South ate areas of California. Avoid use under a heavy America and Asia suggests that breeding for forage tree canopy,however,as cowpeas are susceptible to production would result in improved cultivars mildew if heavily shaded (211). As in much of the (15, 351) and cover crop performance. tropical world where cowpeas are a popular food crop,they can be underseeded into corn for late-sea- Easy to establish. Cowpeas germinate quickly son weed suppression and post-harvest soil cover- and young plants are robust, but they have more age (302). difficulty emerging from crusted soils than soybeans. Seed and feed options. Cowpea seed (yield range 350 to 2,700 lb./A) is valued as a nutrition- MANAGEMENT al supplement to cereals because of complementary protein types.Seed matures in 90 to 240 days. Establishment Cowpeas make hay or forage of highest feed value Don’t plant cowpeas until soil temperature is a when pods are fully formed and the first have consistent 65 F and soil moisture is adequate for ripened (91). A regular sickle-bar mower works germination—the same conditions soybeans for the more upright-growing cultivars (91, 351). need. Seed will rot in cool, wet soils (81). Crimping speeds drying of the rather fleshy stems Cowpeas for green manure can be sown later in to avoid over-drying of leaves summer (302), until about nine before baling. Cowpeas thrive under weeks before frost. Cowpeas grow in a range of well-drained Low moisture need. Once hot, moist conditions, soils from highly acid to neu- they have enough soil moisture but also tolerate drought tral,but are less well adapted to to become established, cow- alkaline soils. They will not peas are a rugged survivor of and low soil fertility. survive in waterlogged soils drought. Cowpeas’ delayed leaf or flooded conditions (91). senescence allows them to survive and recover In a moist seedbed, drill cowpeas 1 to 2 inches from midseason dry spells (15). Plants can send deep at about 30 to 90 lb./A,using the higher rate taproots down nearly 8 feet in eight weeks to in drier or cooler areas or for larger-seeded culti- reach moisture deep in the soil profile (81). vars (302, 351). While 6- to 7-inch row spacings are best for rapid groundcover or a short growing Cultivars for diverse niches. Cover crop culti- season,viny types can be planted in 15- to 30-inch vars include CHINESE RED,CALHOUN and RED RIPPER, rows. Pay particular attention to pre-plant weed

96 MANAGING COVER CROPS PROFITABLY 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). Marianne Sarrantonio Field Management COWPEAS (Vigna unguiculata) Cowpea plants are sometimes mowed or rolled to suppress regrowth before being incorporated for green manure. It’s best to incorporate cowpeas screening in North Carolina. If stinkbugs are a while the entire crop is still green (302) for quickest concern, remember these points: release of plant nutrients.Pods turn cream or brown • Flail mowing or incorporating cowpeas at upon maturity and become quite brittle. Stems pod set will prevent a stinkbug invasion. By that become more woody and leaves eventually drop. time, cowpeas can provide good weed suppres- Crop duration and yield are markedly affected sion and about 90 percent of their nitrogen con- by night and day temperatures as well as day tribution (256). However, waiting too long before length. Dry matter production peaks at tempera- mowing or incorporation will flush stinkbugs tures of 81 F day and 72 F night (91). into adjacent crops. Leaving remnant strips of cowpeas to attract stinkbugs may reduce move- Killing ment into other crops, as long as the cowpeas Mowing at any point stops vegetative develop- keep producing enough new pods until the cash ment, but may not kill plants without shallow crop is no longer threatened. tillage. Recent tests show mowing and rolling • Plan crop rotations so the preceding,adjacent alone do not consistently kill cowpeas (69). Herb- and succeeding crops are not vulnerable or are icides that control cowpeas include glyphosate, resistant to stinkbugs. paraquat, 2,4-D and dicamba (25). • If you plan to use an insecticide to control another pest, the application may also help man- Pest Management age stinkbugs (263). Farmers using cowpeas as cover crops do not No cowpea cultivar is resistant to root rot, but report problems with insects that are pests in there is some resistance to stem rot. Persistent commercial cowpea production, such as Lygus wet weather before development of the first true bugs and 11-spotted cucumber beetle (69, 256, leaf and crowding of seedlings due to poor seed 63). Insect damage to cowpea cover crops is spacing may increase damping off. To reduce most likely to occur at the seedling stage. disease and nematode risks, rotate with four or Once cowpea plants form pods, they may five years of crops that aren’t hosts. Also plant attract stinkbugs,a serious economic pest in parts seed into warm soils and use certified seed of of the lower Southeast. However, no significant tolerant varieties (81). IRON and other nematode- stinkbug presence was reported in three years of tolerant 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 culti- rough spot between milo (grain sorghum) and vator 1 to 2 inches deep just before planting 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 and mineralizable nitrogen. Cowpeas set pods experiments (351). Despite some research (351) over a period of several weeks. Viny varieties showing an increased nematode risk after continue to increase dry matter yields during that cowpeas, California farmers report no such time. problem (256). A mix of 15 lb. cowpeas and 30 lb. buckwheat/A makes it possible to incorporate the Crop Systems cover crop in just six weeks while still providing Cowpeas’ heat-loving nature makes them an ideal some nitrogen. Replacing 10 percent of the mid-summer replenisher of soil organic matter normal cowpea seeding rate with a fast-growing,

98 MANAGING COVER CROPS PROFITABLY drought-tolerant sorghum-sudangrass hybrid frost (211). Sown in July, the cowpea canopy increases dry matter production and helps sup- closed more rapidly and suppressed weeds better port the cowpea plants for mowing (256). than lespedeza (Lespedeza cuneata), American Cowpeas also can be seeded with other tall annu- jointvetch (Aeschynomene americana), sesbania al crops such as pearl millet (see Up-and-Coming and alyceclover (Alysicarpus spp.), the other Cover Crops, p. 158). Overseeding cowpeas into warm-season legumes tested (351). Cowpeas per- nearly mature spring broccoli in June in Zones 5 form better than clovers and alfalfa on poor or and 6 of the Northeast acid soils. Cowpea residue suppresses weeds while Unlike many grain legumes, breaks down faster than improving soil (302). Planting white sweetclover (302) cowpeas in late June or early cowpeas can leave a net N but not as fast as Austrian July in the upper Midwest gain even if seeds are winter peas. after spring canning peas pro- Warm-season alterna- vides green manure or an harvested. tives to cowpeas include emergency forage crop (351). two crops that retain some Cowpeas can fill a mid- cowpea benefits. Buck- summer fallow niche in inland North Carolina wheat provides good beneficial habitat and between spring and summer vegetable crops. A weed control without attracting stinkbugs. mix of IRON AND CLAY cowpeas (50 lb./A) and Velvetbeans (Mucuna deeringiana) provide nitro- German millet (15 lb./A) planted in late June can gen, soil protection and late-season forage in hot, be killed mechanically before no-till transplanted long-season areas. They do not attract stinkbugs fall broccoli.In several years of screening trials at and are resistant to nematodes (81, 263). the same sites, cowpea dry matter (3,780 lb./A) out yielded soybeans (3,540 lb. DM/A), but plots SEED of sesbania (Sesbania exaltata) had top yields at about 5,000 lb. DM/A (69). Cultivars. See Cultivars for diverse niches (p. 96). COMPARATIVE NOTES Seed sources. Adams-Briscoe, Frazier, Lohse Mill, Cowpeas are more drought tolerant than soy- Mangelsdorf, Peaceful Valley and Pennington. See beans, but less tolerant of waterlogging (302) and 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 inter- row ground cover, forage

Mix with: rye and other cereals, vetches, annual ryegrass, subclover, red clover, black medic not recomended summer annual winter annual See charts, p. 47 to 53, for ranking and management summary. marginal (limited by heat, rainfall, short season)

ith its rapid, robust growth, crimson well before grain sorghum, which is planted later clover provides early spring nitrogen than corn. It is being tested extensively in no-till W for full-season crops. Rapid fall growth, and zone-till systems. One goal is to manage to let or summer growth in cool areas, also makes it a the legume reseed yearly for no-cost, season-long top choice for short-rotation niches as a weed- erosion control, weed suppression and nitrogen suppressing green manure.Popular as a staple for- banking for the next year. age and roadside cover crop throughout the Along the northern edge of the “crimson clover Southeast, crimson clover is gaining increased zone,”winterkill and fungal diseases will be more recognition as a versatile summer-annual cover in of a problem. Hairy vetch is the less risky over- colder regions. Its spectacular beauty when flow- wintering winter annual legume, here and in ering keeps it visible even in a mix with other northern areas. Crimson clover often can survive flowering legumes, a common use in California winters throughout the lower reaches of Zone 6, nut groves and orchards. especially from southeastern Pennsylvania northeast to coastal New England (151). BENEFITS Crimson clover is gaining popularity as a winter-killed annual,like oats,in Zones 5 and cold- Nitrogen source. Whether you use it as a spring er. Planted in late summer, it provides good or fall N source or capitalize on its vigorous groundcover and weed control as it fixes nitrogen reseeding ability depends on your location. from the atmosphere and scavenges nitrogen Growers in the “crimson clover zone”—east of from the soil. Its winterkilled residue is easy to the Mississippi, from southern Pennsylvania and manage in spring. southern Illinois south—choose winter annual crimson clover to provide a strong, early N boost. Biomass. As a winter annual, crimson clover can In Hardiness Zone 8—the warmer half of the produce 3,500 to 5,500 lb. dry matter/A and fix Southeast—crimson clover will overwinter 70 to 150 lb. N/A by mid-May in Zone 8 (the dependably with only infrequent winterkill. Its N inland Deep South). In a Mississippi study, crim- contribution is 70 to 150 lb./A. son clover had produced mature seed by April 21, Reseeding cultivars provide natural fertility to as well as 5,500 lb. DM and 135 lb. N/A. The corn and cotton. Crimson clover works especially study concluded that crimson clover is one of

100 MANAGING COVER CROPS PROFITABLY 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 mid- summer 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, Marianne Sarrantonio either as a nurse crop to establish a clear stand of crimson clover,or as a high-biomass,nutrient-scav- CRIMSON CLOVER (Trifolium incarnatum) enging partner. In California, crimson clover is planted with rose clover and medics in orchards and nut groves to minimize erosion and provide es, helps reduce the potential for N leaching into some N to tree crops (351). groundwater during winter and spring (139,213). In field trials of six annual legumes in Mixed with annual ryegrass in a simulated rainfall Mississippi, crimson clover was found to produce study, crimson clover reduced runoff from the the most dry matter (5,600 to 6,000 lb./A) com- herbicide lactofen by 94 percent and norflurazon pared to hairy vetch, bigflower vetch, berseem and fluometuron by 100 percent (286). The clover, arrowleaf clover (Trifolium vesiculosum) grass/legume mixture combines fibrous surface and winter peas. It produced 99 to 130 lb. N/A roots with short tap roots. and is recommended for soil erosion control because of its high early-autumn dry matter pro- MANAGEMENT duction (352). Establishment & Fieldwork Beneficial habitat and nectar source. Crimson Crimson clover will grow well in about any type 1 clover has showy,deep red blossoms /2 to 1 inch of well drained soil, especially sandy loam. It may long. They produce abundant nectar, and are fare poorly on heavy clay, waterlogged, extremely visited frequently by various types of bees. The acid or alkaline soils. Crimson clover establish- blooms may contain many minute pirate bugs, an ment requires moderate temperature and mois- important beneficial insect that preys on many ture, but seedlings are rather robust thanks to small pests, especially thrips (351). Georgia crimson clover’s relatively large seed size. Once research shows that crimson clover sustains pop- established, it thrives in cool, moist conditions. ulations of pea aphids and blue alfalfa aphids. Dry soil often hinders fall plantings in the South. These species are not pests of pecans,but provide Inoculate crimson clover with an R-type (crim- alternative food for beneficial predators such as son clover-berseem) inoculant. Research in lady beetles, which later attack pecan aphids. Alabama showed that deficiencies of phosphorus or potassium—or strongly acidic soil with a pH of Nutrient cycler. Crimson clover adds to the soil less than 5.0—can virtually shut down N fixation. organic N pool by scavenging mineralized N and Nodules were not even formed at pH 5.0 in the by normal legume N fixation. The scavenging test. Phosphorus deficiency causes many small process, accomplished most effectively by grass- but inactive nodules to form (144).

CRIMSON CLOVER 101 Winter annual use. Seed six to eight weeks N/A for fall vegetables. Mid-July seedings have before the average date of first frost at 15 to 18 yielded 5,500 lb./A of weed-suppressing biomass lb./A drilled, 22 to 30 lb./A broadcast. As with by late October. Summer-annual use is planned other winter legumes, the ideal date varies with with the expectation of winter-kill. It sometimes elevation. In North Carolina, for example, the rec- survives the winter even in southern Michigan ommended seeding dates are three weeks later (205), however, so northern experimenters along the coast than in the mountains. should maintain a spring-kill option if icy winds Don’t plant too early or crimson clover will go and heaving don’t do the job. to seed in the fall and not regrow in spring until In California, spring sowing often results in the soil warms up enough to germinate seeds. stunting, poor flowering and reduced seed yield, Early to mid-August seeding is common in the and usually requires irrigation (351). northern part of crimson clover’s winter-annual range.While October plantings are possible in the Rotations. In the South, crops harvested in early lower Mississippi Delta,an August 15 planting in a fall or sown in late spring are ideal in sequence Mississippi test led to higher yields than later with crimson clover. Timely planting of crimson dates (182). In the lower Coastal Plain of the Gulf clover and its rapid spring growth can enable it to South, crimson clover can be planted until mid- achieve its maximum N contribution,and perhaps November (277). reseed. While corn’s early planting date and cot- Nutrient release from crimson clover residue— ton’s late harvest limit a traditional winter-annual and that of other winter annual legumes—is role for crimson clover, strip planting and zone quicker if the cover crop is tilled lightly into the tillage create new niches. By leaving unkilled soil. Apart from erosion concerns, this fertility strips of crimson clover to mature between zone- enhancing step adds cost and decreases the tilled crop rows, the legume sets seed in May. weed-suppression effect early in the subsequent The majority of its hard seed will germinate in fall. crop’s cycle. Kill crimson clover before seed set and use longer season cultivars where regrowth from Summer annual use. In general,plant as soon as hard seed would cause a weed problem. all danger of frost is past. Spring sowing establish- Researchers have successfully strip-tilled into es crimson clover for a rotation with potatoes in standing crimson clover when 25 to 80 percent of Maine. In Michigan, researchers the row width is desiccated with have successfully established In Hardiness Zone 5 a herbicide or mechanically tilled crimson clover after short-season for the planting area. Narrower crops such as snap beans (140). and colder, crimson strips of crimson clover increased In Northern corn fields, clover can provide a weed pressure but reduced mois- Michigan studies showed that ture competition, while wider crimson clover can be overseed- winterkilled mulch. strips favored reseeding of the ed at final cultivation (layby) cover (187, 353). when corn is 16 to 24 inches tall.Crimson clover In a crimson clover-before-corn system, grow- was overseeded at 15 lb./A in 20-inch bands ers can optimize grain yields by no-tilling into between 30-inch rows using insecticide boxes the crimson clover and leaving the residue on and an air seeder.The clover established well and the surface, or optimize total forage yield by har- caused no corn yield loss (238). Crimson clover vesting the crimson clover immediately before has proved to be more promising in this niche planting corn for grain or silage (160). In than black medic, red clover or annual ryegrass, Mississippi, sweet potatoes and peanuts suffered averaging 1,500 lb. DM/A and more than 50 lb. no yield or quality penalty when they were N/A (140). no-tilled into killed crimson clover. The system In Maine, spring-seeded crimson clover can reduced soil erosion and decreased weed com- yield 4,000 to 5,000 lb.DM/A by July,adding 80 lb. petition (21).

102 MANAGING COVER CROPS PROFITABLY In Ohio, crimson clover mixed with hairy A rolling stalk chopper flattens a mix of crim- vetch, rye and barley provided a fertility enhanc- son clover, hairy vetch and rye ahead of no-till ing mulch for no-till processing tomato trans- vegetable transplanting at Steve Groff’s farm in plants. Use of a prototype undercutter implement southeastern Pennsylvania.The crimson is killed with a rolling harrow provided a good kill. completely if it is in full bloom; and even early Because the wide blades cut just under the soil bloom is killed better than vegetative crimson. surface on raised beds, they do not break stalks, Small amounts of metribuzin applied two to thus lengthening residue durability. The long- three weeks after transplanting handle any lasting residue gave excellent results, even under regrowth and provide season-long weed control, organic management without the herbicides, as well (132). Glufosinate-ammonium, paraquat, insecticides or fungicides used on parallel plots cyanazine and glyphosate are other herbicides under different management regimes. Nancy used to kill crimson clover (205). Creamer at the University of North Carolina is continuing work on the undercutter and on cover Pest Management crops in organic vegetable systems (72). Crimson clover is a secondary host to plant pests of the Heliothus species, which include corn ear- Mixed seeding. For cover crop mixtures, sow worm and cotton bollworm. Despite its known crimson clover at about two-thirds of its normal benefits,crimson clover has been eradicated from rate and the other crop at one third to one-half of many miles of roadsides in Mississippi at the its monoculture rate. Crimson request of some Delta farmers clover development is similar to In Mississippi, crimson who suspect it worsens prob- tall fescue. It even can be estab- lems from those pests (77). lished with light incorporation clover produced mature Crimson clover doesn’t sig- in existing stands of aggressive seed and 135 lb. N/A nificantly increase risk of grasses after they have been Southern corn rootworm in no- closely mowed or grazed. by April 21. till corn, while hairy vetch does (47). It is more resistant to dis- Reseeding. Overwintered crimson clover needs eases (351) and to some nematodes than other sufficient moisture at least throughout April to clovers (276). Crimson clover is said to tolerate produce seed. Cultivar selection is critical when viral diseases, but it succumbed to virus in July early spring maturity is needed. plantings in Mississippi (182) and to Sclerotinia DIXIE and CHIEF are full-season standards. AU in fall plantings in Maryland (83). ROBIN and FLAME beat them by about two weeks, In lab tests, crimson clover,berseem clover and while the popular TIBBEE is about a week ahead of hairy vetch have been shown to inhibit germina- the standards. A new cultivar—AU CRIMSON, that tion and seedling development of onion, carrot reportedly would be three weeks earlier—is still and tomato (26). However, this interference has- under development. Price varies more by season- n’t been observed in North Carolina field crops al supply than by cultivar. where strips are mechanically tilled (353), or in other studies with crimson clover as part of a Killing. Its simple taproot makes crimson clover killed organic mulch. No-till vegetable transplant- easy to kill mechanically. Mowing after early bud ing has been done successfully on the same day stage will kill crimson clover. Maximum N is as mechanically killing the cover crop mix on available at late bloom or early seed set, even Steve Groff’s Lancaster County, Pa., farm with no before the plant dies naturally. Killing earlier negative effects (132). yields less N—up to 50 lb. N/A less at its late veg- Wait two to three weeks after incorporating etative stage, which is about 30 days before early covers before planting seeds,to allow the biomass seed set (283). to begin to decompose and the soil biological life

CRIMSON CLOVER 103 to stabilize. During this time, a flush of bacteria reseeding via cattle manure.Timely mowing four such as Pythium and Rhizoctonia attack rapidly to six weeks before bloom improves growth, decaying plants. These bacteria also can attack reduces lodging and will cause more uniform seedling crops. To plant more quickly, mow the flowering and seed ripening on highly fertile soils clover and use row cleaners to clear the tops from (91, 351). the seed zone. The mow/wait/plant cycle also Crimson clover can be grazed lightly in the fall, may be influenced by the need to wait for rain to more intensively in the spring and still be left to increase seedbed moisture. accumulate N and/or set seed with little reduc- Mixed with hairy vetch, crimson clover attracts tion in its soil N contribution (60). beneficial insects, provides nitrogen and suppresses weeds in Oklahoma’s native and planta- COMPARATIVE NOTES tion pecan groves. Both legumes go to seed and then are harvested for forage. Arrowleaf clover Crimson clover is: provided more biomass and N, but didn’t work as • less tolerant of mowing than are subclovers or well for insect pest management (320) and is very medics (351) susceptible to root knot nematode. • similar to hairy vetch and Austrian winter pea Crimson clover harbors flower thrips and is a in the Southeast for total N production more likely host for tarnished plant bug than • quicker-growing than hairy vetch in fall and hairy vetch or subterranean clover (38). Intensive spring screenings show less abundant arthropod herbi- • a better weed suppressor in fall than hairy vores and predators on crimson clover than on vetch hairy vetch (162). • earlier to mature in spring than hairy vetch Tillage practices and residue management vari- Crimson clover produces more dry matter than ations (no-till, incorporate, removal) of cover sweetclover or hairy vetch on a given amount of cropped lupin, rye, hairy vetch or crimson clover rainfall. had little consistent effect on nematodes in north Florida corn fields (212). SEED

Other Options Cultivars. See Reseeding (p. 103) for cultivar Pasture and hay crop. Crimson clover is excel- comparisons. lent for grazing and haying.It will regrow if grazed or mowed no lower than 3 or 4 inches before the Seed Sources. Forage suppliers, including early bud stage. Mixing with grass reduces its rel- Ampac, Kaufman, Missouri Southern, Peaceful atively low bloat risk even further. Seedheads are Valley, Pennington and Sexauer. See Seed easily accessible by grazing livestock, leading to Suppliers (p. 166).

104 MANAGING COVER CROPS PROFITABLY 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 See charts, pp. 47 to 53, for ranking and management summary.

igh N-fixers, field peas produce abundant which can destroy whole fields during winter in vining forage and contribute to short- the mid-Atlantic area. Risk of infection increases if H term soil conditioning. Succulent stems pea crops are grown on the same land in close break down easily and are a quick source of avail- rotation (82). able N (302). Field peas grow rapidly in the cool, Canadian field peas are a related strain of moist weather they encounter as winter annuals vining pea. These annual “spring peas” can out- in the South and in parts of Idaho, and as early- grow spring-planted winter peas. They often sown summer annuals in the Northeast, North are seeded with triticale or another small grain. Central and Northern Plains areas. Harvest Spring peas have larger seeds, so there are fewer options as high-quality forage and seed increase seeds per pound and seeding rates are higher, their value. about 100 to 160 lb./A (237). However, spring Winter-hardy types of field peas, especially pea seed is a bit less expensive than Austrian Austrian winter peas, can withstand tempera- winter pea seed (347). TRAPPER is the most com- tures as low as 10 F with only minor injury, but mon Canadian field pea cultivar. they don’t overwinter consistently in areas colder This section focuses on the widely grown than moderate Hardiness Zone 6.They are sensi- Austrian winter pea. “Field peas” refers to both tive to heat, particularly in combination with the winter and spring types. humidity. They tend to languish in mid-summer even in the cool Northeast (302), where average BENEFITS summers have fewer than 30 days exceeding 86 F. Temperatures greater than 90 F cause flowers to Bountiful biomass. Under a long, cool, moist blast and reduce seed yield. On humus-rich black season during their vegetative stages, Austrian soils, field peas will produce abundant viny winter peas produce more than 5,000 lb.dry mat- growth with few seed pods. ter/A, even when planted in spring in colder Use in the East and Southeast is limited by field climates. Idaho farmers regularly produce 6,000 peas’ susceptibility to Sclerotinia crown rot, to 8,000 lb. DM/A from fall-planted Austrian

FIELD PEAS 105 winter peas (135). Because the residue breaks Rotational effects. Pulse crops (grain legumes down quickly, only peas in the high-production such as field peas, fava beans and lentils) improv- areas build up much long-term organic matter. ed sustainability of dryland crop rotations by pro- Peas do not make a good organic mulch for weed viding disease suppression, better tilth and other control (302). enhancements to soil quality in a Saskatchewan study. Even at rates of 180 lb. N/A, fertilizer alone Nitrogen source. Austrian winter peas are top N was unable to bring yields of barley planted into producers, yielding from 90 to 150 lb. N/A, and at barley residue to the maximum achieved from times up to 300 lb. N/A. these pulse residues (128). Plowed down as green manure, fall-planted legume crops of Austrian winter pea, alfalfa and Water thrifty. In a comparison of water use hairy vetch each produced enough N for the pro- alongside INDIANHEAD lentils and GEORGE black duction of high-quality muskmelons under plastic medic, Austrian winter pea was the most mois- mulch and drip irrigation in a Kansas study.Melon ture-efficient crop in producing biomass. Each yields produced with the legumes were similar to crop had used 4 inches of water when Austrian those receiving synthetic fertilizer at 63 and 90 lb. winter pea vines were 16 inches long, the lentils N/A. The winter peas in the experiment pro- were 6 to 8 inches tall and the black medic cen- duced 96 lb.N/A the first year and 207 lb.N/A the tral tillers were 4 inches tall (316). second (317). Austrian winter peas grown in a controlled Austrian winter peas harvested as hay then setting at 50 F recorded more than 75 percent of applied as mulch mineralized N at more than its N2 fixed per unit of water used by the 63rd double the rate of alfalfa hay.The N contribution day of growth. White clover, crimson clover and was measured the summer after a fall plowdown of hairy vetch reached the same level of water effi- the residue.The estimated N recovery of Austrian ciency,but it took 105 days (273). winter pea material 10 months after incorporation was 77 percent—58 percent through spring wheat Quick growing. Rapid spring growth helps peas and 19 percent in the soil (202). out compete weeds and make an N contribution Austrian winter pea green manure provided the in time for summer cash crops in some areas. highest spring wheat yield the following year in a Montana trial comparing 10 types of medics, Forage booster. Field peas grown with barley, seven clovers, yellow biennial sweet clover and oat, triticale or wheat provide excellent livestock three grains. Crops that produced higher tonnage forage. Peas slightly improve forage yield, but sig- of green manure usually had a negative effect on nificantly boost protein and relative feed value of the subsequent wheat crop due to moisture defi- small grain hay. ciency that continued over the winter between the crops (314). Field peas can leave 80 lb. N/A if Seed crop. Seed production in Montana is about terminated at mid-season in lieu of summer fallow 2,000 lb./A. In the Pacific Northwest, market in dryland areas, or leave more than 30 lb. N/A prices have ranged up to $11 per hundred after pea harvest at season’s end (53). weight. University of Montana economists esti- A winter pea green manure consistently result- mate potential gross returns of $83 to $165/A on ed in higher malting barley protein content than yields of only 1,500 lb./A. Demand is growing for that following other legumes or fallow in a field peas as food and livestock feed (53). Montana trial. Annual legumes harvested for seed left less soil N than did plots in fallow. Also Long-term bloomer.The purple and white blos- tested were fava bean,lentil,chickpea,spring pea, soms of field peas are an early and extended winter pea hay and dry bean (210). source of nectar for honeybees.

106 MANAGING COVER CROPS PROFITABLY 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, Marianne Sarrantonio or interseed into a winter grain. These environ- FIELD PEAS (Pisum sativum subsp. arvense) ments protect young pea roots by suppressing soil heaving during freezing and thawing. Trapped snow insulates plants, as well. West. In mild winter areas of California and Idaho,fall-plant for maximum yield.In those areas, MANAGEMENT you can expect spring-planted winter peas to produce about half the biomass as those that are Establishment & Fieldwork fall-planted. Seed by September 15 in Zone 5 of Peas prefer well-limed, well-drained clay or heavy the Inter-Mountain region in protected valleys loam soils,near-neutral pH or above and moderate where you’d expect mild winter weather and fertility. They also do well on loamy sands in good, long-term snow cover. October-planted North Carolina (282).Field peas usually are drilled Austrian winter pea in the Zone 9 Sacramento 1 to 3 inches deep to ensure contact with moist Valley of California thrive on cool, moist condi- soil and good anchoring for plants. tions and can contribute 150 lb. N/A after being If you broadcast peas, incorporation will great- flail-mowed and disked in early April. ly improve stands,as seed left exposed on the sur- The general rule for other parts of the semi-arid face generally does not germinate well. Long- West where snow cover is dependable is to plant vined plants that are shallow-seeded at low seed- peas in the fall after grain harvest. In these dry ing rates tend to fall over (lodge), lay against the regions of Montana and Idaho, overseed peas at soil and rot. Combat this tendency by planting 90 to 100 lb./A by “frostseeding” any time soils with a small grain nurse crop such as oats, wheat, have become too cold for pea germination. Be barley,rye or triticale.Reduce the pea seeding rate sure residue cover is not too dense to allow seed by about one quarter—and grain by about one to work into the soil through freeze/thaw cycles third—when planting a pea/grain mix. as the soil warms (316). Planted at 60 to 80 lb./A in Minnesota, Austrian In the low-rainfall Northern Plains, broadcast winter peas make a good nurse crop for alfalfa (274). clear stands of peas in early spring at a similar rate Field pea seed has a short shelf life compared for the “Flexible Green Manure” cropping system with other crops. Run a germination test if seed is (below). Seeding at about 100 lb./A compensates more than two years old and adjust seeding rate somewhat for the lack of incorporation and pro- accordingly. If you haven’t grown peas in the vides strong early competition with weeds (316). seeded area for several years, inoculate immedi- Plant as soon as soil in the top inch reaches 40 F ately before seeding. to make the most of spring moisture (53).

FIELD PEAS 107 A mixture of Austrian winter peas and a small the seed with a shallow pass of his field cultivator. grain is suitable for dryland forage production They grow 3 to 6 inches tall before going dormant because it traps snow and uses spring moisture to in late December in his Zone 8 location about 75 produce high yields earlier than spring-seeded miles north of the Gulf of Mexico. Quick regrowth annual forages (53). With sufficient moisture, starts about the third week in January. He kills spring peas typically produce higher forage yields them in mid-April by disking, then shallow plows than Austrian winter peas. to incorporate the heavy residue (158). Farmers and researchers note several IPM East. Planted as a companion crop in early spring cautions, because Austrian winter peas: in the Northeast, Austrian winter peas may pro- • Host some races of nematodes vide appreciable plowdown N for summer crops • Are susceptible to winter Sclerotinia crown by Memorial Day (302). In the mid-Atlantic, rot, Fusarium root rot as well as seed rot and Austrian winter peas and hairy vetch planted Oct. blights of the stem, leaf or pod 1 and killed May 1 produced about the same total • Are variably susceptible to the Ascochyta N and corn yields (83). blight (MELROSE cultivar has some resistance) • Host the pathogen Sclerotinia minor.There Southeast. Seed by October 1 in the inland Zone was a higher incidence of leaf drop in 8 areas of the South so that root crowns can California lettuce planted after Austrian winter become established to resist heaving.Peas produce peas in one year of a two-year test (185). more biomass in the cooler areas of the South than Austrian winter peas were heavily damaged by where temperatures rise quickly in spring (53, Sclerotinia trifoliorum Eriks in several years of a 302). Peas planted in late October in South four-year study in Maryland, but the crop still pro- Carolina’s Zone 8 and terminated in duced from 2,600 to 5,000 lb. dry mid- to late April produce 2,700 to Winter pea residue matter/A per year in four out of 4,000 lb. dry matter/A (17). five years. One year DM produc- breaks down and tion was only 730 lb./A. Mean N Killing releases N quickly. contribution despite the disease Peas are easily killed by disking or was 134 lb. N/A. Overall, Austrian mowing after full bloom, the stage winter peas were rated as being of maturity that provides the optimum N contri- more suited for Maryland Coastal Plain use than in bution. Disk lightly to preserve the tender residue the Piedmont, due to harsher winters in the latter for some short-term erosion control. location (160). The downside to the quick breakdown of pea To combat disease, rotate cover crops to avoid vines is their slimy condition in spring if they win- growing peas in the same field in successive years. terkill, especially in dense, pure stands. Planting To minimize disease risk, waiting several years is with a winter grain provides some protection best. To minimize risk of losing cover crop from winterkill and reduces matting of dead pea benefits to Sclerotinia disease in any given season, vegetation (230). mix with another cover crop such as cereal rye.

Pest Management Crop Systems Winter peas break crop disease cycles,Ben Burkett Northern Plains. Austrian winter pea is a top of Petal, Miss., has found. Septoria leaf spot prob- candidate for dryland grain legume>cereal rota- lems on his cash crops are reduced when he plants tions designed to save N and be adaptable to Austrian winter pea in fall after snap beans and varying amounts of soil moisture. The sequence ahead of collards and mustard greens the next sum- starts with a spring- or fall-planted grain legume mer. Between October 15 and November 15, whose residue substitutes for fallow, followed by Burkett broadcasts just 50 lb./A then incorporates the usual local small grain.

108 MANAGING COVER CROPS PROFITABLY In a “Flexible Green Manure” cropping system, the legume year’s contribution to the small grain the guiding management principles call for the may top $15/A (316). grain legume to be controlled based on the: In Idaho, fall-seeded Austrian winter peas har- • season’s rainfall vested for seed provided income, residual N from • crop’s N fixation the pea straw and soil disease suppression in • anticipated moisture and N need of the a study of efficient uses of the legume cover. A following crop crop rotation of Austrian winter pea>winter When managing for moisture, farmers look at wheat>spring barley produced similar wheat three management paths for their Austrian winter yields as did using the peas as green manure or peas or other grain legume: allowing soil organic matter to break down • Deficient moisture—incorporate the grain during summer fallow in the first year. While legume early to initiate summer fallow. neither Austrian winter pea green manure nor fal- • Adequate moisture—terminate the grain low produced income, the green manure legume when about 4 inches of groundwater improved soil organic matter and added more N have been used. Residue is maintained for for wheat than did summer fallow. Fallow caused green manure, moisture retention and erosion a net soil capacity loss by “mining” finite soil prevention. organic matter reserves (201). • Above-average moisture—crop is left to In a northern Alberta comparison of conven- bear seed for harvest. tional (tilled), chemical (herbicide) and green In conventional fallow systems using tillage or (field pea) fallow systems, spring-planted field herbicide, soil is left unplanted to allow organic peas provided 72 lb. N/A, significantly more than matter to mineralize during a non-crop year to the other systems.The field pea system was also increase available plant nutrients. Fallow systems, more profitable when all inputs were considered, however, still require N fertilizer to compensate providing higher yield for two subsequent cash for the net loss of native soil fertility and have crops, higher income and improvement of soil led to many environmental problems. These quality (8). include saline seep and nitrate pollution of groundwater due to In the Northeast, Southeast. Fall-seeded Austrian leaching of nutrients during the winter peas out-produced hairy fallow period. spring-planted peas vetch by about 18 percent in both Grain legumes provide a soil- can be incorporated dry matter and N production in a protecting alternative that more N three-year test in the Coastal Plain than fallow.The legumes also dis- by Memorial Day. of North Carolina.When legumes rupt disease, insect and weed were grown with rye, wheat or cycles and contribute to long-term soil-building spring oats,Austrian winter pea mixtures also had where limited moisture slows organic matter the highest dry matter yields. Over the three breakdown. Austrian winter peas work in these years, Austrian winter peas ranked the highest rotations where there is at least 18 inches of rain (dry-matter and N) in the legume-only trials and as per year. INDIANHEAD lentils (Lens culinaris the legume component of the legume/grain mix- Medik), a specialty lentil for cover crop use, is tures. In descending order after the peas were widely used in this system. hairy vetch, common vetch and crimson clover. Montana research shows that when soil mois- The peas were sown at 54 lb./A in the sole-seed- ture is replenished by winter precipitation, annu- ings and 41 lb./A in mixtures (285). al legumes can substitute for fallow without In the year of greatest N fixation, soil N in the significantly reducing the yield of the next barley Austrian winter peas mixture treatments was 50 crop. When the legume generates income from percent greater than the average of all other treat- harvest of its hay or grain,fertilizer N savings from ments. Researchers noted that the bottom leaves

FIELD PEAS 109 Peas Do Double Duty for Kansas Farmer PARTRIDGE, Kan.—Jim French figures Austrian colder early and mid-winter temperatures. In winter peas provide free grazing, free nitrogen, most years, he sets up temporary fence and or both.The vining legume produces just as turns his cattle into the peas about April 1 at much N for the following grain sorghum crop the stocking rate of two animal units per acre. even if he lets his registered Gelbvieh herd eat During the best years of mild weather and all they want of the winter annual’s spring adequate moisture,“the cattle have a hard time growth. keeping up,”says French. Depending on his French farms on flat, well-drained sandy need for forage or organic matter, he leaves loam soil near Partridge, Kan. He manages the cattle in until he incorporates the pea about 640 acres each of cash crops (winter stubble, or gives it time to regrow. wheat and grain sorghum) and forages (alfalfa, One reason he gets about the same 90 to 120 sudangrass, winter peas and cowpeas, and an lb. N/A contribution with or without grazing is equal area in grass pasture). Peas follow wheat that the winter pea plants apparently continue in the three-year crop rotation on his south- N fixation and root growth while being grazed. central Kansas farm. He chisel plows the Soil tests show that 25 to 30 lb. N/A are wheat stubble twice about 7 inches deep, available in the nitrate form at incorporation in disks once to seal the surface, then controls late spring, with the balance in an organic form weeds as necessary with a light field cultivator. that mineralizes over the summer. Grazing the Between mid-September and mid-October peas helps to contain cheatgrass, which tends he inoculates about 30 lb./A of the peas and to tie up N if it’s incorporated just ahead of his drills them with an old John Deere double-run sorghum crop. disk drill in 8-inch rows. Establishment is French is sold on winter peas ahead of his usually good, with his only anxiety coming grain sorghum because it provides N while during freeze-thaw cycles in spring.“Each time reducing weed pressure from cheatgrass and the peas break dormancy,start to grow,then pigweed and decreasing lodging from get zapped with cold again they lose some of charcoal root rot.The option to use the their root reserves and don’t have quite the peas as forage—while still achieving adequate resistance to freezing they did.They’ll sprout sorghum yield—lets him buy less processed back even if there’s vegetative freeze damage feed, improves livestock health and accelerates as long as their food reserves hold out,”French conversion of the peas’ organic material into reports. available soil nutrients. Ironically,this spring freezing is less of a “Winter peas work best where you integrate problem further north where fields stay frozen crops and livestock,”says French.“They give longer before a slower thaw.This works as you so many benefits.” long as snow cover protects the peas from the

of pea vines were more decomposed than other release from peas could be excessive, mixing legumes, giving the crop an earlier start in N con- Austrian winter peas with a grain can moderate tribution. Further, soil N in the upper 6 inches of the N contribution and slow down its release into soil under the Austrian winter peas held 30 to 50 the soil (285). percent of the total soil inorganic N in the winter The carbon to nitrogen (C:N) ratio of plant mat- pea treatments, compared with levels of less than ter is an indication of how rapidly vegetation will 30 percent in the top soil layer for all other treat- break down. Mixtures of small grains with ments. In situations where the early-summer N Austrian winter peas and the vetches had C:N

110 MANAGING COVER CROPS PROFITABLY values from 13 to 34,but were generally under 25 Other Options to 30, the accepted threshold for avoiding net Harvest field peas for hay when most of the pods immobilization of N (285). are well formed. Use a mower with lifting guards Austrian winter peas and crimson clover can and a windrow attachment to handle the sprawl- provide adequate N for conventionally planted ing vines. cotton in South Carolina. In a three-year trial, fertilizer rates of up to 150 lb.N/A made no improve- COMPARATIVE NOTES ment to cotton yield on the pea plots. The evaluation showed that soil nitrate under Austrian Field peas won’t tolerate field traffic due to winter peas peaked about nine weeks after incor- succulent stems (147). When selecting types, poration (16). remember that long-vined varieties are better for Austrian winter peas achieved 50 to 60 percent weed control than short-vined types. groundcover when they were overseeded at about 75 lb./A into soybeans at leaf yellowing in SEED southeastern Pennsylvania, where they can survive some winters. The peas produced nearly 2 Cultivars. MELROSE, known for its winterhardi- tons of dry matter and 130 lb. N/A by May 20 in ness, is a cultivar of the Austrian winter pea type. this test (147). Overseeding peas into corn at last Planted the first week of September in Idaho, cultivation is not recommended due to poor MELROSE peas yielded 300 lb.N/A and 6 tons of dry shade tolerance. matter the next June. Planted in Austrian winter peas,like other In dryland systems, mid-April, the cultivar yielded hollow-stemmed succulent cov- “just” 175 lb. N/A and 3.5 T dry ers such as vetch and fava beans, winter peas produce matter/A (158). do not respond well to mowing abundant biomass GRANGER is an improved or cutting after they begin to winter pea that has many fewer bloom. In their earlier stages, with limited moisture. leaves and more tendrils, which Austrian winter peas will regrow are stiffer than standard culti- even when grazed several times. See Peas Do vars. It is more upright and its pods dry more Double Duty for Kansas Farmer (p. 110). quickly than other winter pea types. Seed is After three years of moisture testing, Kansas expected to be commercially available in 1999 farmer Jim French can explain why he sees more (232). MAGNUS field peas have out-produced soil moisture after spring grazing than when the Austrian winter peas in California (168) and peas are left to grow undisturbed. “There’s bloom up to 60 days earlier (256). decreasing overall transpiration because there’s less leaf area to move moisture out of the soil into Seed sources. Forage crop suppliers, and the air. Yet the root mass is about the same.” Albright, Ampac, Ernst, Fedco, Lohse, Peaceful, Ungrazed peas pump more water as they keep Tennessee,Timeless and Wolf. See Seed Suppliers growing. (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

See charts, p. 47 to 53, for ranking vetch, crimson vetch viable crimson hairy vetch viable and management summary. transition zone clover superior w/irrigation

ew legumes match hairy vetch for spring stantial N from vetch is often available before residue production or nitrogen contribu- corn planting (287). Ftion. Widely adapted and winter hardy Corn planting date comparison trials with through the warmer parts of Hardiness Zone 4, cover crops in Maryland show that planting as hairy vetch is a top N provider in temperate late as May 15—the very end of the month-long regions. local planting period—optimizes corn yield and The cover grows slowly in fall, but root devel- profit from the system. Spring soil moisture was opment continues over winter. Growth quickens higher under the vetch than under cereal rye or in spring, when hairy vetch becomes a sprawling with no cover crop. Killed vetch left on the sur- vine up to 12 feet long. Field height rarely face conserved summer moisture for improved exceeds 3 feet unless the vetch is supported by corn production (60, 62, 64, 82, 136, 192). another crop. Its abundant, viny biomass can be a Even without crediting its soil-improving ben- benefit and a challenge. The stand smothers efits, hairy vetch increases N response and pro- spring weeds, however, and can help you replace duces enough N to pay its way in many systems. all or most N fertilizer needs for late-planted Hairy vetch without fertilizer was the preferred crops. option for “risk-averse” no-till corn farmers in Georgia, according to calculations comparing BENEFITS costs, production and markets during the test. The economic risk comparison included crim- Nitrogen source. Hairy vetch delivers plenty of son clover, wheat and winter fallow. Profit was residue to condition soil and heavy contributions higher, but less predictable, if 50 pounds of N of N in mineralizable form (readily available to the were added to the vetch system (250). following cash crop). It can provide sufficient N Hairy vetch ahead of no-till corn was also the for many vegetable crops, partially replace N fer- preferred option for risk averse farmers in a three- tilizer for corn or cotton and increase the crop’s N efficiency for higher yield. Note: To estimate hairy vetch N contribution in In some parts of California (168) and the East in pounds per acre, cut and weigh fresh vetch top Zone 6, hairy vetch provides its maximum N by growth from a 4-foot by 4-foot area. Multiply by 12 safe corn planting dates. In Zone 7 areas of the pounds to gauge available N, by 24 to find total N Southeast, the fit is not quite as good, but sub- (310). See also How Much N? (p. 22).

112 MANAGING COVER CROPS PROFITABLY 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 his- toric 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 (Vicia villosa) Marianne Sarrantonio Hairy vetch provides yield improvements beyond those attributable to N alone. These may be due to mulching effects, soil structure 25 or more tends to immobilize N.For more infor- improvements leading to better moisture reten- mation, see How Much N? (p. 22), and the rest of tion and crop root development, soil biological that section,Building Soil Fertility and Tilth with activity and/or enhanced insect populations just Cover Crops (p. 16). below and just above the soil surface. Early weed suppression. The vigorous spring Soil conditioner. Hairy vetch can improve root growth of hairy vetch out-competes weeds, filling zone water recharge over winter by reducing in where germination may be a bit spotty.Residue runoff and allowing more water to penetrate the from killed hairy vetch has a weak allelopathic soil profile (108). Adding grasses that take up a effect,but it smothers early weeds mostly by shad- lot of water can reduce the amount of infiltration ing the soil. Its effectiveness wanes as it decom- and reduce the risk of leaching in soils with excess poses, falling off significantly after about three or nutrients. Hairy vetch—especially an oats/hairy four weeks.For optimal weed control with a hairy vetch mix—decreased surface ponding and soil vetch mulch, select crops that form a quick crusting in loam and sandy loam soils. Researchers canopy to compensate for the thinning mulch or attribute this to dual cover crop benefits: their abil- use high-residue cultivators made to handle it. ity to enhance the stability of soil aggregates (par- Mixing rye and crimson clover with hairy vetch ticles), and to decrease the likelihood that the (seeding rates of 30,10,and 30 lb./A,respectively) aggregates will dissolve in water (108). extends weed control to five or six weeks, about Hairy vetch improves topsoil tilth, creating a the same as an all-rye mulch. Even better, the mix loose and flowable soil structure. Vetch doesn’t provides a legume N boost,protects soil in fall and build up long-term soil organic matter due to its over winter better than legumes, yet avoids the tendency to break down completely. Vetch is a potential crop-suppressing effect of a pure rye succulent crop, with a relatively “low” carbon to mulch on some vegetables (338). nitrogen ratio. Its C:N ratio ranges from 8:1 to 15:1, expressed as parts of C for each part of N. Good with grains. For greater control of winter Rye C:N ratios range from 25:1 to 55:1, showing annual weeds and longer-lasting residue, mix why it persists much longer under similar condi- hairy vetch with winter cereal grains such as rye, tions than does vetch. Residue with a C:N ratio of wheat or oats.

HAIRY VETCH 113 Growing grain in a mixture with a legume not Irrigation will help germination, but cultivation is only lowers the overall C:N ratio of the combined likely to bury seeds too deeply. residue compared with that of the grain, it may Plant hairy vetch 15 to 45 days before killing actually lower the C:N ratio of the small grain frost for winter annual management; in early residue as well. This internal change causes the spring for summer growth; and in July for fall grain residue to break down faster, while accu- incorporation or a winter-killed mulch. mulating the same levels of N as it did in a mono- Hairy vetch has a relatively high P and K culture (285). requirement and,like all legumes,needs sufficient sulfur and prefers a pH between 6.0 and 7.0. Moisture-thrifty. Hairy vetch is more drought- However,it can survive through a broad pH range tolerant than other vetches. It needs a bit of mois- of 5.6 to 7.5 (91). ture to establish in fall and to resume vegetative An Illinois farmer successfully no-tills hairy growth in spring, but relatively little over winter vetch in late August at 22 lb./A into closely when above-ground growth is minimal. mowed stands of fescue on former Conservation Reserve Program land (348). Using a herbicide to Phosphorus scavenger. Hairy vetch showed kill the fescue is cheaper—$8 to $10 to spray for higher plant phosphorus (P) concentrations than growers owning their equipment vs. $10 to $12 crimson clover, red clover or a crimson/ryegrass to mow—but it must be done about a month later mixture in a Texas trial.Soil under hairy vetch also when the grass is actively growing for the chemi- had the lowest level of P remaining after growers cal to be effective (267). Vetch also can be no- applied high amounts of poultry litter prior to tilled into soybean or corn stubble (32, 60). vegetable crops (92). Farmers in the Northeast’s warmer areas plant vetch by mid-September to net 100 lb. N/A by Fits many systems. Hairy vetch is ideal ahead of mid-May. Sown mid-August, an oats/hairy vetch early-summer planted or transplanted crops, pro- mix can provide heavy residue (138). viding N and an organic mulch. Some Zone 5 Rye/hairy vetch mixtures mingle and moderate Midwestern farmers with access to low-cost seed the effects of each crop. The result is a “hybrid” plant vetch after winter grain harvest in mid-sum- cover crop that takes up and holds some excess mer to produce whatever N it can until it win- soil nitrate,fixes N,stops erosion,smothers weeds terkills—or survives to regrow in spring. in spring and on into summer if not incorporated, contributes a moderate amount of N over a longer Widely adapted. Its high N production, vigorous period than vetch alone,and offsets the N limiting growth, tolerance of diverse soil conditions, low effects of rye.The rye acts as a trellis, making the fertility need and winter hardiness make hairy climbing vetch easier to mow and increasing its vetch the most widely used of winter annual exposure to the sun (61, 63, 64, 310). legumes. In a vetch/rye mixture, an appropriate seeding rate for corn production in the mid-Atlantic MANAGEMENT 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 Establishment & Fieldwork works in a variety of conditions (302),while some Seed into freshly prepared and firmed soil. farmers report success with only 40 lb. rye/A. Broadcast and incorporate lightly to no more than Overseeding (40 lb./A) at leaf-yellowing into 1 1 /2 inches deep.Dry conditions often reduce ger- soybeans can work if adequate rainfall and soil mination of hairy vetch. Drill seed at 15 to 20 moisture are available prior to the onset of freez- lb./A, broadcast 25 to 30 lb./A. Select a higher ing weather. Overseeding into ripening corn (40 rate if you are seeding in spring or late in lb./A) or seeding at layby has not worked as your window, or into a weedy or sloped field. consistently. Late overseeding into vegetables is

114 MANAGING COVER CROPS PROFITABLY possible, but remember that hairy vetch will not He kills the vetch when it is in its pre-bloom or stand heavy traffic (302). bloom stage, nearing its peak N-accumulation capacity. Further delay would risk loss of soil Killing moisture in the dry period customary there in Your mode of killing hairy vetch and managing early June (267). When the no-tilled vetch was left residue will depend on which of its benefits are to grow one season until seed set, it produced 6 most important to you. Incorporation of hairy tons of dry matter and contributed a potentially vetch vegetation favors first-year N contribution, polluting 385 lb. N/A (348).This high dose of N but takes significant energy and labor. Keeping must be managed carefully during the next year vetch residue on the surface favors weed sup- to prevent leaching or surface runoff of nitrates. pression, moisture retention, and insect habitat, A series of trials in Maryland showed a different but may reduce N contribution. mix of conditions. Corn planting in late-April is In spring, hairy vetch continues to add N common there, but early killing of vetch to plant through its “seed set” stage after blooming. corn then had the surprising effect of decreasing Biomass and N increase until maturity, giving soil moisture and corn yield, as well as predictably either greater benefit or a dilemma,depending on lowering N contribution. The earlier-planted corn your ability to deal with vines that become more had less moisture-conserving residue. Late April or sprawling and matted as they mature. early May kill dates, with corn no-tilled 10 days Climate influences the results of hairy vetch later, consistently resulted in higher corn yields residue management. In the hot and humid con- than earlier kill dates (62, 63, 64). With hairy vetch ditions of the Southeast, no-till hairy vetch and a vetch/rye mixture, summer soil water con- residue appears to contribute significant N with- servation by the cover crop residue had a greater out incorporation. Findings elsewhere (272) indi- impact than spring moisture depletion by the cate that farmers in the cooler and drier areas of growing cover crop in determining corn yield (64). the western Corn Belt need to manage hairy Results in the same trials,which also included a vetch with mowing and tillage to achieve peak N pure rye cover, demonstrated the management benefits by preventing N volatilization (loss into flexibility of a legume/grain mix. Early killed rye the atmosphere). protects the soil as it conserves water and N, Mulch-retaining options include strip-tilling or while vetch killed late can meet a large part of the strip chemical desiccation (leaving vetch untreated N requirement for corn. The vetch/rye mixture between the strips), mechanical killing (rotary can conserve N and soil moisture while fixing N mowing, flailing, cutting, sub-soil shearing with an for the subsequent crop.The vetch and vetch/rye undercutter, or chopping/flattening with a rolling mixture accumulated N at 130 to 180 lb./A.The stalk chopper) or broadcast herbicide application. mixture contained as much N—or more—than vetch alone (63). No-till corn into killed vetch.The best time for In an Ohio trial, corn no-tilled into hairy vetch no-till corn planting into hairy vetch varies with at mid-bloom in May received better early season local rainfall patterns, soil type, desired N contri- weed control from vetch mulch than corn seeded bution, season length and vetch maturity. into vetch killed earlier. The late planting date In southern Illinois, hairy vetch no-tilled decreased yield,however (145,289),requiring cal- into fescue provided 40 to 180 lb. N/A over 15 culation to determine if lower costs for tillage, years for one researcher/farmer. He used herbi- weed control, and N outweigh the yield loss. cide to kill the vetch about two weeks before the Once vetch starts to bloom, it is easily killed by area’s traditional mid-May corn planting date. any mechanical treatment (52). To mow-kill for The 14-day interval was critical to rid the field of mulch, rye grown with hairy vetch improves cut- prairie voles, present due to the field’s thick ting by holding the vetch off the ground to allow fescue thatch. more complete severing of stems from roots. Rye

HAIRY VETCH 115 also increases the density of residue covering the sunny day after full spring growth begins. Usually, vetch stubble to prevent regrowth. N contribution by early bloom (10-25 percent) Much quicker and more energy-efficient than stage warrants killing the legume, rather than mowing is use of a modified Buffalo rolling stalk accepting yield loss due to late planting to get chopper, an implement designed to shatter stand- marginally more N at seed set or natural dry down ing corn stubble. The chopper’s rolling blades after seed set. break over, crimp and cut crop stems at ground Cutting hairy vetch close to the ground at full level, and handle thick residue of hairy vetch or bloom stage usually will kill it. However, waiting foxtail millet at 8 to 10 mph (131). this long means it will have maximum top growth,and the tangled mass of mature vetch can No-till vegetable transplanting. Vetch that is overwhelm many smaller mowers or disks. Flail suppressed or killed without disturbing the soil mowing before tillage helps,but that is a time- and maintains moisture well for transplanted vegeta- horsepower-intensive process. Sickle-bar mowers bles. No-till innovator Steve Groff of Lancaster should only be used when the vetch is well sup- County, Pa., uses the rolling stalk chopper to cre- ported by a cereal companion crop and the mate- ate a killed organic mulch. His favorite mix is 25 rial is dry (351). lb. hairy vetch, 30 lb. rye and 10 lb. crimson Heavy disk harrows, rotovators and power clover/A (132). spaders can incorporate heavy, unmowed vetch stands. A moldboard plow can turn under large No-till, delayed kill. Jeff Moyer of the Rodale amounts of mowed vetch. Chisel plows and Institute in Kutztown, Pa., no-tills corn into stand- lighter disks can handle vetch killed earlier with ing hairy vetch in late May or early June, waits herbicides. several more days, then flail-chops the vetch before corn emergence. This method allows the Harvesting seed. Plant hairy vetch with grains if vetch to produce maximum N and is late enough you intend to harvest the vetch for seed. Use a to allow soil warming even with the vetch in moderate seeding rate of 10-20 lb./A to keep the place (230). stand from getting too rank (132). Vetch seed- Also useful in killing hairy vetch on raised beds pods will grow above the twining vetch vines and for vegetables and cotton is the improved proto- use the grain as a trellis, allowing you to run the type of an undercutter that cutter bar higher to reduce leaves severed residue virtu- Winter hardy through the plugging of the combine. ally undisturbed on the sur- Direct combine at mid- face (70). The undercutter warmer parts of Zone 4, few bloom to minimize shatter- tool includes a flat roller legumes can rival hairy ing, or swath up to a week attachment, which, by itself, later. Seed is viable for at usually provides only partial vetch’s N contributions. least five years (302). suppression unless used If you want to save dollars after flowering. by growing your own seed, be aware that the Herbicides used to kill hairy vetch include mature pods shatter easily, increasing the risk of glyphosate (only somewhat effective), paraquat, volunteer weeds. To keep vetch with its nurse 2,4-D, dicamba and triazines including atrazine, crop, harvest vetch with a winter cereal and keep cyanazine and metribuzin.Vetch will die in three seed co-mingled for planting. Check the mix care- to 30 days (338), depending on the material used fully for weed seeds. and crop conditions. Management Cautions Vetch incorporation. As a rule, to gauge the • About 10 to 20 percent of vetch seed is “hard” optimum hairy vetch kill date, credit vetch with seed that lays ungerminated in the soil for one or adding two to three pounds of N per acre per more seasons. This can cause a weed problem,

116 MANAGING COVER CROPS PROFITABLY especially in winter grains. With wheat, you can kondoi) that do not attack pecans but provide a use 2,4-D for control. After a corn crop that can food source for aphid-eating insects that can dis- utilize the vetch-produced N, you could establish perse into pecans. (40). Similarly,hairy vetch blos- a hay or pasture crop for several years. soms harbor flower thrips (Frankliniella spp.), • Don’t plant hairy vetch with a winter grain if which in turn attract important thrip predators you want to harvest grain for feed or sale. such as insidious flower bugs (Orius insidiosus) Production is difficult because vetch vines will and minute pirate bugs (Orius tristicolor). pull down all but the strongest stalks. Grain cont- Two insects may reduce hairy vetch seed yield amination also is likely if the vetch goes to seed in heavy infestations: the vetch weevil or vetch before grain harvest.Vetch seed is about the same bruchid.Rotate crops to alleviate buildup of these size as wheat and barley kernels, making it hard pests (302). and expensive to separate during seed cleaning (302). Grain price can be markedly reduced by CROP SYSTEMS only a few vetch seeds per bushel (82). • A severe freeze with temperatures less than 5 Killed hairy vetch creates a short-term but effec- F may kill hairy vetch if there is no snow cover, tive spring/summer mulch, especially for trans- reducing or eliminating the stand and most of its plants. The mulch retains moisture, allowing N value. If winterkill is possible plants to use mineralized nutri- in your area, planting vetch with Mix hairy vetch with ents better than unmulched a hardy grain such as rye ensures fields. The management chal- spring soil protection. cereal grains to reduce lenge is that the mulch also low- the risk of N leaching. ers soil temperature, which may Pest Management delay early season growth (302). In legume comparison trials, One option is to capitalize on hairy vetch usually hosts numerous small insects high quality, low-cost tomatoes that capture the and soil organisms (162). Many are beneficial to late-season market premiums. See Vetch Beats crop production, (see below) but others are Plastic (p. 118). pests. Soybean cyst nematode (Heterodera How you kill hairy vetch influences its ability glycines) and root-knot nematode (Meliodogyne to suppress weeds.Durability and effectiveness as spp.) sometimes increase under hairy vetch. If a light-blocking mulch are highest where the you suspect that a field has nematodes, carefully stalks are left whole. Hairy vetch severed at the sample the soil after hairy vetch.If the pests reach roots or sickle-bar mowed last longer and blocks an economic threshold, plant nematode-resistant more light than flailed vetch, preventing more crops and consider using another cover crop. weed seeds from germinating (70, 340). Other pests include cutworms (302) and While there is evidence that hairy vetch southern corn rootworm (47), which can be exudes weak natural herbicides that may inhibit problems in no-till corn; tarnished plant bug— development of small onion, carrot and tomato noted in coastal Massachusetts (38)—which read- seedlings (26), these compounds do not affect ily disperses to other crops; and two-spotted transplants (132). spider mites in Oregon pear orchards (107). Southern farmers can use an overwintering Leaving unmowed remnant strips can lessen hairy vetch crop in continuous no-till cotton. movement of disruptive pests while still allowing Vetch mixed with rye has provided similar or you to kill most of the cover crop (38). even increased yields compared with systems that Prominent among predator beneficials associated with hairy vetch are lady beetles,seven-spotted Note: An unmown rye/hairy vetch mix sustained ladybeetles (38) and bigeyed bugs (Geocaris a population of aphid-eating predators that was spp.). Vetch harbors pea aphids (Acyrthosiphon six times that of the unmowed volunteer weeds pisum) and blue alfalfa aphids (Acyrthosiphon and 87 times that of mown grass and weeds (39).

HAIRY VETCH 117 Vetch Beats Plastic BELTSVILLE, Md.—Killed cover crop mulches • Transplant seedlings using a minimum tillage can deliver multiple benefits for no-till planter able to cut through the mulch and vegetable crops.The system can provide its firm soil around the plants. own N, quell erosion and leaching, and The hairy vetch mulch suppresses early displace herbicides. It’s also more profitable season weeds. It improves tomato health by than conventional commercial production preventing soil splashing onto the plants, and using black plastic mulch. A budget analysis keeps tomatoes from soil contact, improving showed it also should be the first choice of quality.Hairy vetch-mulched plants may need “risk averse” farmers.These are individuals more water. Their growth is more vigorous who prefer certain although more modest and may yield up to 20 percent more than profit over higher average profit that is less those on plastic. Completing harvest by mid- certain (178). September allows the field to be immediately The key to the economic certainty of a reseeded to hairy vetch.Waiting for vetch to successful hairy vetch planting is its low bloom in spring before killing it and the tight cost—about $80/A for seeding and mowing— fall turnaround may make this system less compared with the black plastic at about $750 useful in areas with a shorter growing season for plastic, installation and removal. than this Zone 7, mid-Atlantic site. From refining his own research and on-farm Abdul-Baki rotates season-long cash crops of tests in the mid-Atlantic region for several tomatoes, peppers and cantaloupe through the years, USDA’s Aref Abdul-Baki of the ARS same plot between fall hairy vetch seedings. Beltsville (Md.) Agricultural Research Center, He shallow plows the third year after outlines his approach: cantaloupe harvest and seeds hairy vetch for • Prepare beds—just as you would for planting flat-field crops of sweet corn or snap beans tomatoes—at your prime time to seed hairy the following summer. vetch. He suggests seeding rye with the vetch • Drill hairy vetch at 40 lb./A, and expect (40 lb./A each) for greater biomass and longer- about 4 inches of topgrowth before lasting mulch. Adding 10-12 lb./A of crimson dormancy,which stretches from mid- clover will aid in weed suppression and N December to mid-March in Maryland. value. Rolling the covers before planting • After two months’ spring growth, flail mow provides longer-lasting residue than does or use other mechanical means to suppress mowing them. Some weeds, particularly the hairy vetch. Be ready to remow or use perennial or winter annual weeds, can still herbicides to clean up trouble spots where escape this mixture, and may require hairy vetch regrows or weeds appear. additional management (2).

include conventional tillage, winter fallow weed Cotton yields following incorporated hairy cover and up to 60 pounds of N fertilizer per acre. vetch were perennial winners for 35 years at a Typically, the cover crops are no-till drilled after northwestern Louisiana USDA site. Soil organic shredding cotton stalks in late October. Covers matter improvement and erosion control were are spray killed in mid-April ahead of cotton plant- additional benefits (222). ing in May. With the relatively late fall planting, hairy vetch delivers only part of its potential N in Other Options this system. It adds cost, but supplies erosion Spring sowing is possible, but less desirable than control and long-term soil improvement (21). fall establishment because it yields significantly

118 MANAGING COVER CROPS PROFITABLY less biomass than overwintering stands. Hot to be heat tolerant. This has resulted in two weather causes plants to languish. apparent types,both usually sold as “common”or Hairy vetch makes only fair grazing—livestock “variety not stated” (VNS). One has noticeably do not relish it. Heavy feeding for 20 days in hairy hairy, bluish-green foliage with bluish flowers vetch pasture resulted in death for eight of 33 cat- and is more cold-tolerant. The other type has tle in one trial in South America (351). smoother, deep-green foliage and pink to violet flowers. COMPARATIVE NOTES A closely related species—LANA woolypod vetch (Vicia dasycarpa)—was developed in Hairy vetch is better adapted to sandy soils than Oregon and is less cold tolerant than Vicia vil- crimson clover (285), but is less heat-tolerant than losa. Trials in southeastern Pennsylvania with LANA woolypod vetch.See Woolypod Vetch (p.151). many accessions of hairy vetch showed bigflower vetch (Vicia grandiflora, cv WOODFORD) was the SEED only vetch species hardier than hairy vetch. EARLY COVER hairy vetch is said to be 10 days earlier than Cultivars. MADISON—developed in Nebraska— regular common seed (337). tolerates cold better than other varieties. Hairy vetches produced in Oregon and California tend Seed sources. Widely available.

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 annual medics See charts, p. 47 to 53, for ranking (dryland) marginal utility and management summary.

nce established, few other legumes out- duce almost as much biomass and N as clovers. perform medics in soil-saving,soil-building Medics are self-reseeding with abundant “hard Oand forage when summer rainfall is less seed”that can take several years to germinate. This than 15 inches. They serve well in seasonally dry makes medics ideal for long rotations of forages areas from mild California to the harsh Northern and cash crops in the Northern Plains and in cover Plains. With more rainfall, however, they can pro- crop mixtures in the drier areas of California.

MEDICS 119 Annual medics include 35 known species BENEFITS that vary widely in plant habit, maturity date and cold tolerance. Most upright varieties resemble Good N on low moisture. In dryland areas, alfalfa in their seeding year with a single stalk and most legumes offer a choice between N produc- short taproot.Medics can produce more than 100 tion and excessive water use. Medics earn a place lb. N/A in the Midwest under favorable condi- in dryland crop rotations because they provide N tions,but have the potential for 200 lb.N/A where while conserving moisture comparable to bare- the plants grow over winter. They germinate ground fallow (313, 347). Fallow is the intention- and grow quickly when soil moisture is adequate, al resting of soil for a season so it will build up forming a thick ground cover that holds soil in moisture and gain fertility by biological break- place. The more prostrate species of annual down of organic matter. Black medic increased medic provide better ground cover. spring wheat yield by about 92 percent compared Significant annual types include: bur medic (M. with spring wheat following fallow, and also polymorpha), which grows up to 14 inches tall, is appreciably raised the grain protein level (312). semi-erect or prostrate, hairless, and offers great April soil N value after black medic in one seed production and N-fixing ability; barrel medic Montana test was 117 lb./A, about 2.5 times the (M. truncatula), about 16 inches tall, with many fallow N level and the best of six cultivars tested, mid-season cultivars; and all of which used less water snail medic (M. scutellata), Hard-seeded medics are than the fallow treatment which is a good biomass and (311). GEORGE grows in a N producer. ideal for reseeding systems prostrate to ascending fash- Southern spotted bur in orchards and vineyards. ion and overwinters well medic is a native M. polymor- with snow cover in the pha cultivar with more win- Northern Plains. terhardiness than most of the current bur medics, which are imported from Australia. See Southern Great N from more water. Under normal dry- Bur Medic Offers Reseeding Persistence (p. 122). land conditions,medics usually produce about 1 T Naturalized bur medic seed is traded locally in dry matter/A, depending on available soil mois- California (58). ture and fertility. When moisture is abundant, Annual medics broadcast in spring over wheat medics can reach their full potential of 3 T/A of stubble in Michigan reduced weed number and 3.5 to 4 percent plant-tissue nitrogen, contribut- growth of spring annual weeds prior to no-till ing more than 200 lb. N/A (157, 351). corn planting the following spring.Spring-planted annual medics produced dry matter yields similar Fight weeds. Quick spring regrowth suppresses to or greater than alfalfa by July (308). early weeds. Fall weeds are controlled by medic GEORGE black medic (M. lupulina) is usually regrowth after harvest, whether the medic stand called a perennial. It can improve soil, reduce dis- is overseeded or interplanted with the grain, or eases, save moisture and boost grain protein the grain is seeded into an established medic when grown in rotations with grains in the stand. In California orchards and vineyards where Northern Plains. GEORGE is the most widely used winters are rainy instead of frigid, medics mixed cultivar in dryland areas of the Northern Plains. with other grasses and legumes provide a contin- Black medic produces abundant seed. Up to 96 uous cover that crowds out weeds. In those situa- percent of it is hard seed, much of it so hard seed- tions, medics help reduce weed seed production ed that it won’t germinate for two years. Second- for the long-term. year growth may be modest, but coverage improves in years three and four after the initial Boost organic matter. Good stands of medics in seeding if competition is not excessive (351) and well drained soil can contribute sufficient residue grazing management is timely. to build soil organic matter levels. One Indiana

120 MANAGING COVER CROPS PROFITABLY 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 self- frosts after June 10 now and then, too few seeded medic, Alger added to the seed bank 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 sorghum- the field closely in ’98 to make sure the sudangrass hybrid as emergency forage on May darnel, an annual, doesn’t go to seed. 15. He had several inches of growth when frost To plant winter wheat into the seven-year- hit about June 10 and killed the tender grass. old medic sward in fall ’97, he used three 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 maturation, then resume clipping or grazing matter/A from a spring-sown barrel medic (129). (227, 351, 357).

Reduce soil erosion. Medics can survive in sum- Provide good grazing. Green plants, dry plants mer drought-prone areas where few other culti- and burs of bur medic provide good forage, but vated forage legumes would, thanks to their solid stands can cause bloat in cattle (351). The hard-seeded tendency and drought tolerance. burs are concentrated nutrition for winter forage, Low, dense vegetation breaks raindrop impact but lower the value of fleece when they become while roots may penetrate 5 feet deep to hold soil embedded in wool. Annual medics overseeded in place. into row crops or vegetables can be grazed in fall after cash crop harvest (217). Tolerate regular mowing. Medics can be grazed or mowed at intervals with no ill effects. Reseeding. Black medic has a high percentage of They should be mowed regularly to a height of 3 hard seed.Up to 90 percent has an outer shell that to 5 inches during the growing season for best resists the softening by water and soil chemicals seed set and weed suppression. To increase the that triggers germination (228).Scarified seed will soil seed bank, rest medic from blooming to seed 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 Up- for single-season cover crop benefits, insect- and-Coming Cover Crops, p. 158) reseeded icides may be warranted in the seeding year 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 being returned to pasture. This use requires live- medic seed in the intact bur remains viable for a stock for maximum economic benefit. GEORGE longer time than hulled seed (91). black medic is prostrate,allowing other grasses and Their status as a resilient,reseeding forage makes forbs to become the overstory for grazing.It is well- medics the basis for the “ley system” developed in suited to cold winter areas of Hardiness Zone 4, dry areas of Australia. Medics or subterranean where it can stay green much of the winter (3). clover pastured for several years on Australian dry- lands help to store moisture and build up soil pro- Quick starting. Black medic can germinate with- ductivity for a year of small grain production before in three days of planting (228). About 45 days

122 MANAGING COVER CROPS PROFITABLY 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 SearsElayne for fallow in dry northern regions of the U.S. with BLACK MEDIC (Medicago lupulina) 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 valu- germination and winter survival are dependable, able as these better-known legume green although spring planting also has worked. manures (316). • Spring grain nurse crop. Barley, oats, Medics are widely adapted to soils that are rea- spring wheat and flax can serve as nurse crops for sonably fertile, but not distinctly acid or alkaline. medic, greatly reducing weed pressure in the Excessive field moisture early in the season can seeding year. The drawback is that nurse crops significantly reduce medic stands (308). Acid-tol- will reduce first-year seed production if you are erant rhizobial strains may help some cool-season trying to establish a black medic seed bank. To medics, especially barrel medic, to grow on sites increase the soil seed reserve for a long-term that otherwise would be inhospitable (351). black medic stand (germinating from hard seed), To reduce economic risk in fields where you’ve allow the medic to blossom, mature and reseed never grown medic, sow a mixture of medics during its second year. with variable seed size and maturation dates. In • Corn overseed. SANTIAGO bur medic was dry areas of California, medic monocultures are successfully established in no-till corn three to six planted at a rate of 2 to 6 lb./A,while the rate with weeks after corn planting, but biomass and weed grasses or clovers is 6 to 12 lb./A (351). suppression were negligible during a two-year Establishment options vary depending on trial in Michigan. Medic seed was broadcast, then climate and crop system: lightly incorporated as dicamba herbicide was 1 1 • Early spring—clear seed. Drill /4 to /2 inch sprayed over the corn to control weeds. Because deep (using a double-disk or hoe-type drill) into a of variable and generally disappointing results firm seed bed as you would for alfalfa. Rolling is throughout the upper Midwest, current medic recommended before or after seeding to improve species and cultivars are not recommended for seed-soil contact and moisture in the seed zone. underseeding in corn (308). Seeding rate is 8 to 10 lb./A for black medic,12 to Where medic and corn work together, such as 20 lb./A for larger-seeded (snail, gamma and bur) California, maximize medic survival during the annual medics. In the arid Northern Plains, fall corn canopy period by seeding early (when corn

MEDICS 123 is eight to 16 inches tall) and heavy (15 to 20 effective N sources. Further, the long-lived seed lb./A) to build up medic root reserves (31, 351). bank that black medic establishes may be unde- • After wheat harvest. MOGUL barrel medic sirable for some cash crop rotations in areas of seeded after wheat harvest produced 119 lb. N/A higher rainfall (316). in southern Michigan, more than double the N Use of medics in the upper Midwest is still in production of red clover seeded at the same time the exploratory stage.In a series of trials in Ohio, (308). Planted even at mid-season in Montana, Michigan, Wisconsin and Minnesota, medic did snail medic establishes well, smothers weeds, not provide enough weed control or N to justify builds up N, then winterkills for a soil-holding its use under current cash grain prices, even organic mulch. when premiums for pesticide-free corn were • Autumn seeding.Where winters are rainy in evaluated (308). One Michigan farmer’s situation California, medics are planted in October as win- is fairly typical. He established annual medic at ter annuals (358). Plant about the same time as 10 lb./A when his ridge-tilled corn was about crimson clover in the Southeast, Zones 7 and 8. knee-high. The legume germinated, but didn’t grow well or provide weed suppression until Killing after corn dry-down in mid-September. The Medics are easy to control by light tillage or medic put on about 10 inches of growth before herbicides. They reseed up to three times per winterkilling, enough for effective winter ero- summer,dying back naturally each time.Medics in sion protection (157). the vegetative stage do not tolerate field traffic. Soybeans offer a better economic window for medics to work. The expected yield loss is rela- Field Management tively smaller (6 bu./A) and higher pesticide-free Black medic>small grain rotations developed in premiums could make the system profitable,even Montana count on successful self-reseeding of with lower yield. In 1995, an economic analysis medic stands for grazing by sheep or cattle. A showed that a premium of 72 cents per bushel month of summer grazing improves the econom- over a base price of $6.50 would have made ics of rotation by supplying forage for about one medic a profitable weed-control option, without animal unit per acre. In counting its soil-building this system, established, Medics earn a place in dryland value (308). self-reseeding black medic Black medic and two plowed down as green rotations because they provide annual medics produced manure in alternate years N while conserving moisture. 50 to 150 lb. N/A when improved spring wheat interplanted with standard yield by about 50 percent and semi-dwarf barley in a compared to fallow (313). Minnesota trial.Annual MOGUL produced the most Black medic is a dual-use legume in this adapt- biomass by fall, but also reduced barley yields. ed “ley” system. Livestock graze the legume in the GEORGE was the least competitive and fixed “medic years” when the cover crop accumulates 55 to 120 lb. N/A. The taller barley was biomass and contributes N to the soil. Cash crops more competitive, indicating that taller small can be no-tilled into the medic,or the legume can grain cultivars should be used to favor grain pro- be incorporated. duction over medic stand development (231). A well-established black medic stand can Midwestern farmers can overseed annual reduce costs compared with annual crops by medic or a medic/grass mixture into wheat in coming back for many years. However, without very early spring for excellent early summer graz- the livestock grazing benefit to supply additional ing. With timely moisture, you can get a hay cut- utilization, water-efficient legumes such as lentils ting within nine to 10 weeks after germination, and Austrian winter peas will probably be more and some species will keep working to produce a

124 MANAGING COVER CROPS PROFITABLY second cutting. Regrowth comes from lateral quat, 2,4-D and dicamba kill medic effectively stems, so don’t clip or graze lower than 4 or 5 (25). One report says bur medic is very sensitive inches if you want regrowth. To avoid bloat, to 2,4-D. manage as you would alfalfa (157). Pods and viable seeds develop without pollina- Annual medics can achieve their full potential tors because most annual medics have no floral when planted after a short-season spring crop nectaries (91). such as processing peas or lettuce. Wisconsin tests at six locations showed medic produced an COMPARATIVE NOTES average of 2. 2 T/A when sown in the late June or early July (327). Early planting in this window Snail medic produced about the same biomass with a late frost could give both forage and N- and N as red clover when both legumes were bearing residue, protecting soil and adding spring spring sown with an oats nurse crop into a disked fertility. Take steps to reduce weed pressure in seedbed in Wisconsin. Yields averaged over one solid seedings, especially in early July. wet year and one dry year were about 1 T dry mat- In another Michigan comparison,winter canola ter and 60 lb. N/A (308). (Brassica napus) yields were similar after a green Medics can establish and survive better than manure comparison of two medics, berseem subterranean clover in times of low rainfall, and clover and NITRO annual alfalfa. All the covers are more competitive with grasses. A short period were clear (sole-crop) seeded in early May after of moisture will allow medic to germinate and pre-plant incorporated herbi- send down its fast-growing cide treatment, and were With abundant moisture, taproot, while subclover plowed down 90 days later. needs more consistent mois- Harvesting the medics at 60 medics can produce more ture for its shallower, slower days as forage did not signifi- than 200 lb. N/A. growing roots (351). Medics cantly lessen their green are more susceptible than manure value (308). subclover to seed production In the mid-Atlantic at the USDA Beltsville, Md., loss from closely mowing densely planted erect site, medics have been hard to establish by over- stalks. Bur and barrel medics are not as effective seeding at vegetable planting or at final cultiva- as subclover at absorbing phosphorus (351). tion of sweet corn (338). Medics may survive where true clovers (Trifolium spp.) fail due to droughty conditions Pest Management (351) if there is at least 12 in.of rain per year (234). Under water logged conditions for which they are Medics grow well in mixtures with grasses and ill-suited, annual medics are susceptible to dis- clovers, but don’t perform well with red clover eases like Rhizoctonia, Phytophthora and (351, 211). Once established, black medic handles Fusarium (217). frost better than crimson or red clover. Bur medic harbors abundant lygus bugs in GEORGE grows more slowly than yellow blos- spring. It also appears to be particularly prone to som sweetclover in spring of the second year,but outbreaks of the two-spotted spider mite, a pest it starts flowering earlier. It uses less water in the found in many West Coast orchards (351). 2- to 4-foot depth than sweetclover, soybeans or Most medics tolerate low doses of the herbi- hairy vetch seeded at the same time (295). cide 2-4,D-amine and glysophate.They are somewhat resistant to 2-4,DB (351). Other herbicides SEED compatible with medics include EPTC, bro- moxynil before medic emergence and bentazon Annual Medic Cultivars. Species and cultivars and imidazolinone on medic seeded with imida- of annual medic vary significantly in their dry mat- zolinone-resistant corn (217). Glysophate, para- ter production, crude protein concentration and

MEDICS 125 total N. Check with local or regional forage than JEMALONG, commonly used in California (200, specialists for cultivar recommendations 351).SELPHI,a mid-season cultivar,has a more erect Bur medic (also called burclover) cultivars are habit for better winter production, is adapted to the best known of the annual medics. They high- and low-rainfall areas, yields more seed and branch profusely at the base, and send out pros- biomass than others, has good tolerance to trate stems that grow more erect in dense stands Egyptian alfalfa weevil and high tolerance to spot- (351). They grow quickly in response to fall ted alfalfa aphid and blue green aphid. It is sus- California rains and fix from 55 to 90 lb.N/A,near- ceptible to pea aphid. ly as much as true clovers (236, 351). Most stands Snail medic (M. scutellata) is a prolific seed are volunteer and can be encouraged by proper producer. Quick germination and maturity can grazing, cultivation or fertilization. lead to three crops (two reseedings) in a single Selected cultivars include SERENA (an early season from a spring planting in the Midwest bloomer), and CIRCLE VALLEY, both of which have (308).MOGUL barrel medic grew the most biomass fair tolerance to Egyptian alfalfa weevil (357). in a barley intercrop,compared with SANTIAGO bur SANTIAGO blooms later than SERENA. Early bur medic and GEORGE black medic in a four-site medics flower in about 62 days in California,rang- Minnesota trial. It frequently reduced barley ing up to 96 days for mid-season cultivars (351). yields, particularly those of a semi-dwarf barley Naturalized and imported bur medic proved variety, but increased weed suppression and N the best type of burclover for self-reseeding cover and biomass production (231). crops in several years of trials run In a Michigan test of forage from northern California into Medics are easy to legumes for emergency forage Mexico in the 1990s. While some use, MOGUL barrel medic pro- of the naturalized strains have kill with light tillage duced 1.5 T dry matter/A com- been self-reseeding for 30 years in or most herbicides. pared to about 1 T/A for SAVA snail some orchards, Extension special- medic and SANTIAGO bur medic ists say the commercial cultivars (M. polymorpha). Nitrogen pro- may be preferable because they are widely avail- duction was 66 lb./A for MOGUL,46 for SAVA and 22 able and better documented (58). for SANTIAGO.The seeding rate for SAVA medic is 29 Established bur medic tolerates shade as a com- lb./A,more than twice the 13 lb./A recommended mon volunteer in the understories of California for clear seedings of MOGUL and SANTIAGO (308). walnut orchards, which are heavily shaded from In a California pasture comparison of three April through November. However, in Michigan annual medics, JEMALONG barrel had the highest trials over several years, SANTIAGO (a bur medic level of seed reserves in the soil after six years,but with no spines on its burs) failed to establish sat- didn’t continue into the seventh year after the ini- isfactorily when it was overseeded into corn and tial seeding. GAMMA medic (M. rugosa) had the soybeans at layby. Researchers suspect the crop highest first-year seed production but re-estab- canopy shaded the medic too soon after planting, lished poorly, apparently due to a low hard seed and that earlier overseeding may have allowed the content. All the medics re-established better medic to establish (134). under permanent pasture than under any rota- There are at least 10 cultivars of barrel medic. tional system involving tillage (68, 351). Dates of first flowering for barrel medics range from 80 to 105 days after germination, and seed Seed sources. Widely available in California; count per pound ranges from 110,000 for nationally through Kamprath, Peaceful Valley, HANNAFORD to 260,000 for SEPHI (351). A leading Timeless and Wolf River. See Seed Suppliers new cultivar, SEPHI, flowers about a week earlier (p. 166).

126 MANAGING COVER CROPS PROFITABLY RED CLOVER Trifolium pratense

Also called: medium red clover (multi-cut, early blooming, June clover); mammoth clover (single- cut, 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 spring seeded biennial winter annual See charts, p. 47 to 53, for rankings and management summary.

ed clover is a dependable, low-cost, readily showed that 50 percent of the cover crop N was available workhorse that is winter hardy in released in the first month after incorporation, R much of the U.S. (Hardiness Zone 4 and corresponding well with corn’s fertility demand. warmer). Easily overseeded or frostseeded into Post-harvest soil N levels in the clover plots were standing crops, it creates loamy topsoil, adds a the same or less than the fertilized plots, and moderate amount of N, helps to suppress weeds about the same as unfertilized plots (329). and breaks up heavy soil. Its most common uses include forage,grazing,seed harvest,plowdown N Widely adapted. While many other legumes can and, in warmer areas, hay. It’s a great legume to grow quicker, produce more biomass and fix frostseed or interseed with small grains where more nitrogen, few are adapted to as many soil you can harvest grain as well as provide weed types and temperate climatic niches as red clover. suppression and manage N. As a rule, red clover grows well wherever corn grows well. It does best in cool conditions. BENEFITS In southern Canada and the northern U.S., and in the higher elevations of the Southeast and Crop fertility. As a cover crop, red clover is used West,red clover grows as a biennial or short-lived primarily as a legume green manure killed ahead perennial. At lower elevations in the Southeast, it of corn or vegetable crops planted in early grows as a winter annual, and at lower elevations summer. Full-season, over-wintered red clover in the West and Canada, it grows under irrigation can produce 2 to 3 T dry matter/A and fix nitro- as a biennial (91).It grows in any loam or clay soil, gen at 70 to 150 lb. /A. responding best to well-drained, fertile soils. Two years of testing in Wisconsin showed that conventionally planted corn following red clover Many economic uses. Red clover has been a yielded the same as corn supplied with 160 lb. popular,multi-use crop since European immigrant N/A, with less risk of post-harvest N leaching. farmers brought it to North America in the 1500s. Further, monitoring of the corn and the soil It remains an important crop thanks to its greater

RED CLOVER 127 adaptability, lower seeding cost and easier estab- beneficials than white clover,which features high- lishment than alfalfa. It can produce up to 8,000 er N fixation and greater flood tolerance than red lb. biomass/A (277). clover (209). A red clover/small grain mix has been a traditional pairing that continues to be profitable. A Two Types rotation of corn and oats companion-seeded with Two distinct types of red clover have evolved red clover proved as profitable as continuous from the same species. Be sure you plant a culti- corn receiving 160 lb. N/A in a four-year var with the regrowth option if you plan to make Wisconsin study (328). Both had gross margins of more than one green manure cutting, or to main- about $166/A, with fertilizer nitrogen figured at tain the stand to prepare for a late-summer veg- $0.12/lb. as anhydrous ammonia. etable planting. Red clover was the most profitable of five legumes under both seeding methods in the Medium red clover. Medium red (some call it trial—sequentially planted after oats harvest or multi-cut) grows back quickly, and can be cut companion planted with oats in early spring. once late in the seeding year and twice the fol- The companion seedings yielded lowing year.For optimum N benefit nearly twice as much estimated fer- Red clover can and flexible cropping options from tilizer replacement value as the seq- the planting (allowing it to over- uential seedings. The work showed yield 2 to 3 tons winter as a soil-protecting mulch), that red clover holds great potential of dry matter and you can use it for hay, grazing or to reduce fertilizer N use for corn seed throughout the second sea- grown in rotation (329). 70 to 150 lb. N/A son. Seed may be priced the same Red clover sown as a companion as single-cut types (240), or it can with spring oats outperformed the other leg- be up to 25 percent more than single-cut. See umes, which suffered from insect damage, Chart 3B: Planting (p. 51). mechanical damage during oat harvest and slow Mammoth red clover produces as much N subsequent regrowth. The short season proved pound for pound and will produce significant bio- inadequate for sequentially seeded legumes with mass in a single first cutting,but does not produce the exception of hairy vetch, which was nearly as as much biomass overall as medium red’s multiple profitable as the red clover. cuttings over time. Use this “single-cut”red clover The role of red clover’s N contribution in the where a field will be all-clover just during the rotation grew more significant in 1996 when N seeding year. Slow-growing mammoth doesn’t prices had risen 83 percent, even though clover bloom the establishment year and regrows quite seed price had also risen 40 percent from the orig- slowly after cutting, but can provide good bio- inal 1989 calculations. A corn>soybean>wheat/ mass by the end of even one growing season. red clover sequence had a gross margin of $17/A A single cutting of mammoth will give slightly more than continuous corn and nearly $10/A more more biomass—at a slightly lower cost—than a than an oats>corn rotation in 1996 (326). single cutting of medium red. Where multiple cuttings or groundcover are needed in the second Soil conditioner. Red clover is an excellent soil season, medium red clover’s higher seed cost is conditioner, with an extensive root system that easily justified (153). permeates the topsoil. Its taproot may penetrate Some types of mammoth do better overseeded several feet. into wheat than into oats. ALTASWEDE (Canadian) mammoth is not as shade tolerant as MICHIGAN Attracts beneficial insects. Red clover earned a mammoth, but works well when seeded with co-starring role with LOUISIANA S-1 white clover in oats. MICHIGAN mammoth shows the best vigor pecan orchard recommendations from Oklahoma when frostseeded into wheat, but is not as State University in 1996. Red clover attracts more productive as medium red (183).

128 MANAGING COVER CROPS PROFITABLY MANAGEMENT year Michigan trial that used N isotopes to track nitrogen fixation. Red clover and three other Establishment & Fieldwork legumes were no-till drilled into wheat stubble in In spring in cool climates, red clover germinates August, then chemically killed by mid-May just in about seven days—quicker than many ahead of no-till corn. Clover even in this short legumes—but seedlings develop slowly,similar to niche shows good potential to suppress weeds winter annual legumes. Traditionally it is drilled and reduce N fertilizer application (104). at 8 to 12 lb./A with spring-sown grains, using • Soybeans at leaf-yellowing. Sowing the auxiliary or “grass seed”drill boxes.Cut back small clover seed with annual or perennial ryegrass as a grain seeding rates up to 50 percent from pure nurse crop keeps the soil from drying out until stand rates, if clover for forage is your main goal. the clover becomes established (153). Wisconsin researchers who have worked for sev- Whenever possible, lightly incorporate clover eral years to optimize returns from red clover/ seed with a harrow. Wait about six weeks to oats interseedings say planting oats at 3 to 4 bu./A establish a red clover stand in soil treated with gives good stands of clover without sacrificing pre-emergent herbicides such as atrazine. Check grain yield (326). herbicide labels for rotational crop plant-back Red clover’s tolerance of shade and its ability to intervals, and remember that cool temperature germinate down to 41 F give it a remarkable range will slow herbicide breakdown (240). of establishment niches. It can be overseeded at 10 to 18 lb./A into: Killing • Dormant winter grains before ground For peak N contribution, kill red clover at about thaws. This “frostseeding”method relies on move- mid-bloom in spring of its second season. If you ment of the freeze-thaw cycle to work seed into can’t wait that long, you can kill it earlier to plant sufficient seed-soil contact for germination. field corn or early vegetables. If you want to har- Michigan farmers frostseed red clover at 6 to 8 vest the first cutting for hay, compost or mulch, lb./A (240). If the soil is level and firm, you can kill the regrowth in late summer as green manure broadcast seed over snow cover on level terrain. for fall vegetables (153). If avoiding escapes or You can seed the clover with urea if fertilizer clover regrowth is most important, terminate as application is uniform (183). Use just enough soon as soil conditions allow. Actively growing N fertilizer to support proven small-grain yields, red clover can be difficult to kill mechanically because excess N application will hinder clover (106), but light fall chisel plowing followed by a establishment. To reduce small grain competition second such treatment has worked well in sandy with clover in early spring, graze or clip the small loam Michigan soils (240). grain in early spring just before the stems begin to To kill clover mechanically in spring, you can grow (91). Hoof impact from grazing also helps till,chop or mow it any time after blooming starts. ensure seed-to-soil contact. You can shallow plow,or use a chisel plow about • Summer annuals such as oats, barley, spelt 2 to 3 inches deep. Use overlapping shovels, such or spring wheat before grain emergence. as 16-inch sweeps on shanks spaced 12 inches on • Corn at layby. Wait until corn is 10 to 12 center. Chop (using a rolling stalk chopper), flail inches tall, at the V-4 to V-6 growth stage. Clover or sicklebar mow about seven to 10 days ahead of sown earlier in favorable cooler conditions with no-till planting, or use herbicides such as atrazine, more light may compete too much for water. cyanazine, paraquat or glyphosate (25), which Later, the clover will grow more slowly and not works best in fall (240). add substantial biomass until after corn harvest A summer mowing can make it easier to kill red lets light enter (153). Dairy producers often clover with herbicides in fall. Michigan recom- broadcast red clover after corn silage harvest. mendations call for mowing (from mid-August in • After wheat harvest. Red clover logged a northern Michigan to early September in south- fertilizer replacement value of 36 lb.N/A in a two- ern 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).

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 three- year rotations including two full years of red clover, the clover can be incorporated or surface- applied (clipped and left on the field) for green manure, cut for mulch or harvested for hay (91).

Marianne Sarrantonio Red clover in a corn>soybean>wheat/red clover rotation in a reduced-input system out-per- RED CLOVER (Trifolium pratense) formed continuous corn by $53 per acre in a four- year Wisconsin study. The legume cover crop system used no commercial fertilizer, no insecti- weeks. If not mechanically killing, spray with 2 cides and herbicides on only two occasions— quarts of glyphosate and a quart of 2,4-D ester per once to-spot spray Canada thistles and once as a acre. The daytime high air temperature should be rescue treatment for soybeans. Rotary hoeing and above 60 F (so that the plants are actively grow- cultivating provided weed control. ing). When soil temperature drops below 50 F, Gross margins were $195 for the corn>soy- biological decomposition slows to the point that beans>wheat/red clover and $151 for continuous mineralization of N from the clover roots and top- corn using standard agricultural fertilizers,insecti- growth nearly stops (183). cides and herbicides. Top profit in the study went to a corn>soybean rotation with a gross margin of Field Evaluation $209, using standard inputs (218, 326). In Michigan, plant counts are used to estimate roughly how much N a clover stand will con- Pest Management tribute to the immediately following crop. The If poor establishment or winterkill leads to weed formula is 30 + 0.30 x % stand,where 100 percent growth that can’t be suppressed with clipping or stand is five to six plants per square foot in the grazing, evaluate whether your anticipated cover second year of growth. So a field where your crop benefits warrant weed control. MCPA is counts showed an average of six plants per square labeled for broadleaf weed control in winter foot would contribute about 60 lb. N/A (30 + annuals with clover seedings, but care must be [0.30 x 100] 30 = 60). With four plants per square taken to avoid seedling injury (183). foot, percent stand is 4/6 or 66 percent, so the N Never plant dry beans or soybeans after clover contribution is 50 lb./A (30 + [.30 x 66] 20). unless the cover has been thoroughly incorporat- The Michigan field calculation reflects the con- ed by plowing. Limited herbicide options may be ventional rule of thumb that about half of the total unable to control clover escapes that survive in N fixed by a legume will mineralize during the fol- the bean crop (183). lowing growing season and be available to that Root rots and foliar diseases typically kill com- season’s crop (183). However,Wisconsin research mon medium red clover in its second year,making

130 MANAGING COVER CROPS PROFITABLY it function more like a biennial than a perennial. Red clover and sweetclover both perform best on Disease-resistant cultivars that persist three to well-drained soils, but will tolerate poorly drained four years cost 20 to 40 cents more per pound soils. Alsike thrives in wet soils (306). and are unnecessary for most green manure appli- Red clover has less tendency to leach phos- cations. When fertilizer N cost is high, however, phorus (P) in fall than some non-legume covers.It remember that second-year production for some released only one-third to one-fifth the P of annu- improved varieties is up to 50 percent greater al ryegrass and oilseed radish, which is a winter- than for common varieties. annual brassica cover crop that scavenges large Bud blight can be transmitted to soybeans by amounts of N. Figuring the radish release rates— volunteer clover plants (295). even balanced somewhat by the erosion suppression of the covers—researchers determined that Other Management Options P runoff potential from a quick-leaching cover Mow or allow grazing of red clover four to six crop can be as great as for unincorporated weeks before frost in its establishment year to manure (220). prepare it for overwintering. Remove clippings For early fall plowdown, alsike clover (with a for green manure or forage to prevent plant dis- seeding cost of about $9/A) may be a cheaper ease. Red clover reaches its N source than mammoth at prime feeding value at five to 15 Few legumes are as $15.50/A, assuming similar N days after first bloom. Under yields (253). ideal condition, medium red widely adapted as red Red clover and alfalfa showed clover can be cut four times, clover, which can be multi-year benefits to succeed- mammoth only once. Maximum ing corn crops, justifying a cred- cutting of medium one year will used as green manure, it of 90 lb. N/A the first year for come at the expense of second- forage or seed crop. red clover (153) and 50 lb. N/A year yield and stand longevity the second year (326). The third (326).Red clover and red clover/ legume in the trial, birdsfoot grass mixtures make good silage if wilted slightly trefoil (Lotus corniculatus), was the only one of before ensiling or if other preservative techniques the three that had enough third-year N contribu- are used (91). tion to warrant a credit of 25 lb. N/A (113). If an emergency forage cut is needed,harvest red clover in early summer, then broadcast and lightly SEED incorporate millet seed with a tine harrow or disk. Millet is a heat-loving grass used as a cover and for- Cultivars. KENLAND,KENSTAR,ARLINGTON, and age in warm-soil areas of Zone 6 and warmer (see MARATHON are improved varieties of medium red Up-and-Coming Cover Crops, p. 158). clover with specific resistance to anthracnose and mosaic virus strains. They can persist three or COMPARATIVE NOTES even four years with ideal winter snow cover (65). CHEROKEE is more suited to the Coastal Plain Medium red clover has similar upper-limit pH tol- and lower South, and has superior resistance to erance as other clovers at about 7.2. It is general- rootknot nematode (277). ly listed as tolerating a minimum pH of 6.0—not quite as low as mammoth, white or alsike Seed sources. Widely available. Companies (Trifolium hybridum) clovers at 5.5—but it is specializing in forage crops have several said to do well in Florida at the lower pH (277). 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 reseeding cool season annual See charts, p. 47 to 53, for ranking spring seeded fall seeded and management summary.

ubterranean clovers offer a range of low- Diversity of Types, Cultivars growing, self-reseeding legumes with high N Select among the many subclover options culti- Scontribution, excellent weed suppression vars that fit your climate and your cover crop and strong persistence in orchards and pastures. goals. Identify your need for biomass (for mulch Fall-planted subclovers thrive in Mediterranean or green manure),time of natural dying to fit your conditions of mild, moist winters and dry sum- spring-planting schedule and prominence of seed mers on soils of low to moderate fertility, and set for a persistent stand. from moderately acidic to slightly alkaline pH. Subclovers comprise three Trifolium species: Subclover mixtures are used on thousands of • T. subterraneum. The most common cultivars acres of California almond orchards,where farmers that thrive in acid to neutral soils and a continue to evaluate some 50 cultivars for opti- Mediterranean climate mum combinations. Subclover holds promise in • T. yanninicum. Cultivars best adapted to the coastal mid-Atlantic and Southeast (Hardiness water-logged soils Zone 7 and warmer) on sandy loam to clay soils as • T. brachycalcycinum. Cultivars adapted to a killed or living mulch for summer or fall crops. alkaline soils and milder winters Most cultivars require at least 12 inches of rain Primary differences between these species are per year. A summer dry period limits vegetative their moisture requirements,seed production and growth, but increases hard seed tendency that days to maturity (15). Other variables include: leads to self-reseeding for fall reestablishment. • Overall dry matter yield Subclovers generally grow close to the ground, • Dry matter yield at low moisture or low piling up their biomass in a compact layer. A fertility Mississippi test showed that subclover stems were • Season of best growth (fall, winter or spring) about 6, 10 and 17 inches long when the canopy • Hard-seeding tendency was 5, 7 and 9 inches tall, respectively (79). • Grazing tolerance

132 MANAGING COVER CROPS PROFITABLY Subclover cultivars often are described by their California vegetable fields where a high-residue, moisture preference and days to maturity, which high-N cover is desired (345). are closely linked traits. The maturity estimates In legume test plots along the Maryland shore, are set for continuous growing days, and will be subclover mulch controlled weeds better than greatly lengthened for fall-planted subclovers in conventional herbicide treatments. The only the East and Southeast, where winter weather weed to penetrate the subclover was a fall infes- delays flowering for two to three months. tation of yellow nutsedge.The cover crop regrew • Short season subclovers tend to set seed in fall from hard seed in the second and third quickly. Cultivars such as DALKEITH (an improved years of the experiment (19). version of DALIAK) and NUNGARIN need only 8 to 10 inches of rainfall and set seed about 85 days after Green manure. In east Texas trials, subclover planting. Early subclovers tend to be less winter delivered 100 to 200 lb. N/A after spring plow- hardy (77). down. Grain sorghum planted into incorporated • Intermediate types such as TRIKKALA and the subclover or berseem clover with no additional N new,more competitive GOSSE thrive with 14 to 20 yielded about the same as sorghum planted into inches of rain and set mature disked and fertilized soil with- seed in about 100 days. Subclovers thrive in out a cover crop in three out of • Long-season cultivars such four years. The fertilized fields as KARRIDALE and NANGEELA per- Mediterranean climates had received 54 lb. N/A (192). form best with 18 to 26 inches of mild, moist winters of rainfall, setting seed in about Versatile mulch. Subclover 130 days. MT.BARKER was a long- and dry summers. provides two opportunities for time research standard that is use as a mulch in vegetable sys- now surpassed by KARRIDALE for forage produc- tems. In spring, you can no-till early planted crops tion, hardseed percentage, re-establishment po- after subclover has been mechanically or chemi- tential and grazing. KARRIDALE is more prostrate, cally killed, or plant later, after subclover has set and is favored for cover crop use (345). seed and dried down naturally (19). In fall, you can manage new growth from self reseeding to BENEFITS provide a green living mulch for cold-weather crops such as broccoli and cauliflower (165). Weed suppressor. Subclover can produce 3,000 Conventionally tilled corn without a cover crop to 8,500 lb. dry matter/A in a thick mat of stems, in a New Jersey test leached up to 150 lb. N/A petioles (structures connecting leaves to stems) over winter while living subclover prevented N and leaves. Denser and less viny than hairy vetch, loss (99). Mowing was effective in controlling a it also persists longer as a weed-controlling living mulch of subclover in a two-year California mulch. trial with late-spring, direct-seeded sweet corn Subclover mixtures help West Coast orchardists and lettuce.This held true where subclover stands achieve season-long weed management. In Coastal were dense and weed pressure was low. Planting California, fast-growing TRIKKALA, a mid-season cul- into the subclover mulch was difficult, but was tivar with a moderate moisture requirement,jumps done without no-till equipment (189). out first to suppress weeds and produces about twice as much winter growth during January and Soil loosener. In an Australian study in com- February as the other subclovers. It dies back natu- paction-prone sandy loam soil, lettuce yield dou- rally as KOALA, (tall) and KARRIDALE (short) come on bled following a crop of subclover. Without the strong in March and April. The three cultivars clover, lettuce yields were reduced 60 percent on complement each other spatially and temporally the compacted soil.Soil improvement was credited for high solar efficiency,similar to the interplanting to macropores left by decomposing clover roots of peas, purple vetch, bell beans and oats in and earthworms feeding on dead mulch (323).

SUBTERRANEAN CLOVERS 133 levels, and nine other subclover cultivars had lower levels than the crimson (38).

Home for beneficial insects. In tests of eight cover crops or mixtures intercropped with canta- lope 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

Elayne SearsElayne predator level, they did not make a significant SUBTERRANEAN CLOVER difference in control of the target pest, fall army- (Trifolium subterraneum) worm (Spodoptera frugiperda) (38).

Erosion fighter. Subclover’s soil-hugging, dense, Great grazing. Subclovers are highly palatable matted canopy is excellent for holding soil (77). and relished by all livestock (91). Seeded with perennial ryegrass,tall fescue or orchardgrass,sub- Disease-free. No major diseases restrict subclovers add feed value as they improve produc- clover acreage in the U.S. (15). tivity of the grasses by fixing nitrogen. In California, subclover is used in pasture mixtures MANAGEMENT on non-irrigated hills. Perennial ryegrass is preferred for pasture through early summer,especial- Establishment ly for sheep (249). Subclovers grow best when they are planted in late summer or early autumn and grow until Insect pest protection. In the Netherlands, sub- early winter. They go dormant over winter and clover and white clover in cabbage suppressed resume growth in early spring. In late spring, pest insect egg laying and larval populations plants flower and seeds mature in a bur at or enough to improve cabbage quality and profit below the soil surface (hence the name subter- compared with monocropped control plots. ranean clover) as the plant dries up and dies. A Eliminating pesticide costs offset the reduced dense mulch of dead clover leaves and long peti- weight of the cabbages in the undersown plots. oles covers the seeds, which germinate in late Primary pests were Mamestra brassicae, summer to establish the next winter’s stand Brevicoryne brassicae and Delia brassicae. (98). Their persistence over many seasons Undersowing leeks with subclover in the justifies the investment in seed and careful Netherlands greatly reduced thrips that cannot be establishment. controlled by labeled insecticides, and slightly In California, sow in September or early reduced leek rust,a disease that is difficult to con- October to get plants well established before cool trol. While leek quality improved, the quantity of weather (249). Planting continues through leeks produced was reduced considerably (344). November in the most protected areas (281). When tarnished plant bug (Lygus lineolaris) is In marginally mild areas, establish with grasses a potential pest, subclover may be the legume for winter protection. Subclover stimulates the cover crop of choice, based on a Georgia com- grasses by improving soil fertility. You can over- parison among subclovers, hybrid vetches and seed pasture or range land without tillage,but you crimson clover. MT.BARKER had particularly low can improve germination by having livestock

134 MANAGING COVER CROPS PROFITABLY trample in the seed. Subclover often is aerially After stems get long and seed sets, you can kill applied to burned or cleared land. Initial growth plants with a grain drill (77). will be a little slower than that of crimson, but a In northern Mississippi, subclover was the least little faster than white clover (91). controlled of four legumes in a mechanical kill Broadcast at 20-30 lb./A in a well-prepared, test. The cover crops were subjected to being weed-free seedbed that is firm below a depth of rolled with coulters spaced 4 inches apart when 2 inches. Cover seed with a light, trailing harrow the plants had at least 10 inches of prostrate or with other light surface tillage to a depth of growth. While hairy vetch and crimson clover less than one-half inch. Add lime if soil is highly were 80 to 100 percent controlled, berseem acid—below pH 5.5 (249). Soils low in pH may control was 53 percent and subclover was require supplemental molybdenum for proper controlled only 26 to 61 percent (79). growth, and phosphorus and sulfur may also be Researchers in Ohio had no trouble killing limiting nutrients. Only the T. yanninicum culti- post-bloom subclover with a custom-built under- vars will tolerate standing water or seepage cutter.The specialized tool is made to slice 1 to 2 areas (15, 249). inches below the surface of Subclover often is planted Subclover mixes help keep raised beds.The undercutter with rose clover and crimson consisted of two blades clover in California orchard weeds in check all season that are mounted on upright mixes. Crimson and sub- long in West Coast orchards. standards on either side of clover usually dominate, but the bed and slant backward hard-seeded rose clover per- at 45 degrees toward the sists when dry weather knocks out the other center of the bed.A mounted rolling harrow was two (368). attached to lay the cover crop flat on the surface In the East, central Mississippi plantings are after being cut (70). The tool, which continues to recommended Sept. 1 to Oct. 15, although earlier be modified,severs stalks from roots while above- plantings produce the earliest foliage in spring ground residue is undamaged, greatly slowing (91).In coastal Maryland where MT.BARKER plants residue decomposition (69). were tallest and most lush, winterkill (caused Glysophate and dicamba (25) materials work when the temperature dropped to 15 F or better for controlling subclover than do paraquat below) has been most severe. Planting in this (77) and 2,4-D (186). Subclover tolerance to her- area of Zone 7 should be delayed until the first bicides varies with cultivar and growth stage. two weeks of October.Plant at about 22 lb./A for Generally,subclover is easier to kill after it has set cover crop use in the mid-Atlantic (19) and some seed (78, 130). Southeast (77). This is about double the usual recommended rate for pastures in the warmer Reseeding Management soils of the Southeast. The “over-summering”fate of reseeding subclover Small plants of ground-hugging subclover ben- plantings is as critical to their success as is the efit more from heat radiating from the soil than over-wintering of winter-annual legumes. The larger plants, but are more vulnerable during thick mat of vegetation formed by dead residue times of freezing and thawing.Where frost heav- can keep subclover seeds dormant if it is not dis- ing is expected, earlier planting and well-estab- turbed by grazing,tillage,burning or seed harvest. lished plants usually survive better than smaller Where cover crop subclover is to be grazed ones (77). before another year’s growth is turned under, intensive grazing management works best to Killing reduce residue but to avoid excess seed bur con- Subclover dies naturally in early summer after sumption (249). Grazing or mowing in late spring blooming and seed set. It is relatively difficult to or early summer helps control weeds that grow kill without deep tillage before mid-bloom stage. through the mulch (234).

SUBTERRANEAN CLOVERS 135 You can improve volunteer regrowth of sub- WIMMERA) mulch. An alfalfa mulch showed no such clover in warm-season grass mixes by limiting N allelopathic effect in an Australian study (323). fertilization during summer, and by grazing the Guard against moisture competition from grass shorter until cold temperatures limit grass subclover at planting. Without irrigation to growth. This helps even though subclover ensure crop seeds will have enough soil mois- seedlings may emerge earlier (15). Seed produc- ture to germinate in a dry year, be sure that the tion in Oregon was best following grazing from subclover is killed seven to 14 days prior to just prior to the start of flowering until the time planting to allow rainfall to replenish soil of early bur fill (15). Subclover flowers are incon- moisture naturally (19). spicuous and will go unnoticed without careful, eye-to-the-ground inspection (77). Soil-borne crop seedling disease. In north After plants mature, livestock will eagerly eat Mississippi tests, residue and leachate from seed heads (91). In dry years when you want to legume cover crops (including subclover) caused maintain the stand, limit grazing over summer to greater harm to grain sorghum seedlings, com- avoid over-consumption of seed heads and deple- pared to nonlegumes. Rhizoctonia solani, a soil- tion of the seed bank. Close mowing or grazing borne fungus, infected more than half the can be done any time. sorghum seedlings for more than a month, but Some subclover seed (primarily MT.BARKER) is disappeared seven to 13 days after legume produced in Oregon and sold locally for forage residues were removed (75). use. Most commercial subclover seed is produced in Australia. Subclover cultivars were developed N-leaching. The early and profuse nodulation of there for use in “ley” cropping. In this system, subclovers that helps grass pastures also has a sheep or other livestock graze the legume for downside—excess N in the form of nitrate can several years. Then the land is cropped briefly contaminate water supplies. Topgrowth of sub- before being pastured again as the hard seeds of clover, black medic and white clover leached 12 subclover re-establish a stand. to 26 lb.N/A over winter,a rate far higher than red clover and berseem clover, which leached only 2 Management Challenges to 4 lb. N/A in a Swedish test (181). Possible crop seedling suppression. The allelopathic compounds that help subclover sup- Pest Management press weeds also can hurt germination of some Subclovers showed little resistance to root-knot crops.To avoid problems with these crops, delay nematodes in Florida tests on 134 subclover lines planting or remove subclover residue. No-till in three years of testing the most promising planters equipped with tine-wheel row cleaners varieties (186). can reduce the recommended 21-day waiting Lygus species, important pests of field, row period that allows allelopathic compounds to and orchard crops in California and parts of the drop to levels that won’t harm crops (75). Kill Southeast, were notably scarce on subclover subclover at least a year before planting peach plants in a south Georgia comparison. Other trees to avoid a negative effect on seedling vigor. legumes harboring more of the pests were, in It’s best to wait until August of the trees’ second descending order, CAHABA and VANTAGE vetch, summer to plant subclover in row middles, an hairy vetch, turnip and monoculture crimson Arkansas study found (43). clover (38). The degree to which a cover crop mulch Most cultivars imported to the U.S. are low hinders vegetable seedlings is crop specific. Plant- in estrogen, which is present in sufficient levels toxic compounds from subclover mulch suppres- in some Australian cultivars to reduce fertility sed lettuce,broccoli and tomato seedlings for eight in ewes, but not in goats or cattle. Confirm estro- weeks, but not as severely or as long as did com- gen status of a cultivar if you plan to graze sheep pounds from ryegrass (Lolium rigidum cv. on it (249).

136 MANAGING COVER CROPS PROFITABLY Crop Systems with planting new seed, this method yields larger Interseeded with wheat. NANGEELA subclover seedling populations, and growth usually begins provided 59 lb. N/A when it was grown as an earlier in the fall. The flood period seems to interseeded legume in soft red winter wheat in enhance dormancy of both subclover and crim- eastern Texas. That extra N helped boost the son clover, and germination is robust when the wheat yield 283 percent from the previous year’s fields are drained (77). Formerly, some Louisiana yield when four subclover cultivars were first rice farmers seeded the crop into dry soil then let established and actually decreased yield, com- it develop for 30 days before flooding. Early vari- pared with a control plot. NANGEELA,MT.BARKER, eties such as DALKEITH and NORTHAM may make WOOLGENELLUP and NUNGARIN cultivars boosted seed prior to the recommended rice planting wheat yield by 24, 18, 18, and 11 bu./A, respec- date. In recent decades,“water planting” has been tively, in the second year of the study. Over all used to control red rice, a weedy relative of three years, the four cultivars added 59, 51, 38 domestic rice. Water seeding into cover crop and 24 lb. N/A, respectively (29). residues has not been successful (22). Plant breeder Gerald Ray Smith of Texas A&M University worked with several subclovers in east- Fertility, weed control for corn. In the humid ern Texas. While the subclovers grew well the mid-Atlantic region, grain and silage corn no-tilled first year,he concluded that those cultivars need a into NANGEELA subclover did well in a six-year prolonged dry period at maturity to live up to New Jersey trial. With no additional N, the sub- their reseeding performance in Australia and clover plots eventually out-yielded comparison California. Surface moisture at seed set reduces plots of rye mulch and bare-soil that were con- seed hardening and increases seed decay. Mid- ventionally tilled or minimum-tilled with fertilizer summer rains cause premature germination that at up to 250 lb. N/A. The subclover contributed robs the subclover seed bank, especially in pas- up to 370 lb. N/A (99), an N supply requiring tures where grasses tend to create moist soil careful management after the subclover dies to (318). Most summer-germinating plants die when prevent leaching. dry weather returns. Control of fall panicum was poor in the first In Mississippi, subclover hard seed develop- year, but much better the next two years. Control ment has been quite variable from year to year. In of the field’s other significant weed, ivyleaf morn- dry years, close to 100 percent hard seed is devel- ing glory, was excellent in all years. Even though oped. Dormancy of the seed breaks down more no herbicide was used in the subclover plots, rapidly on bare soil with wider temperature weed biomass was lowest there (99). swings than it does on mulched soils (100, 101). Central New Jersey had mild winters during To facilitate reseeding or to seed into pastures,the these experiments. Early spring thaws triggered grasses must be mowed back or grazed quite subclover regrowth followed by plunging tem- short for the subclover to establish (77). peratures that dropped below 15 F.This weak- ened the plants and thinned the stands. The Mix for persistence. California almond growers surviving plants, which formed dense stands at need a firm, flat orchard floor from which to pick times, were mowed or strip-killed using herbi- up almonds. Many growers use a mix of moisture- cides or tillage. Mowing often induced strong tolerant TRIKKALA, alkaline-tolerant KOALA, and regrowth, so strips at least 12 inches wide proved KARRIDALE, which likes neutral to acid soils.These to be the best to prevent moisture competition blended subclovers give an even cover across between the subclover and the cabbage and moist swails and alkaline pockets (345). zucchini transplants (165).

Rice N-source. In Louisiana trials, subclover Sustainable sweet corn. On Maryland’s Eastern regrew well in fall when allowed to set seed Shore (one USDA hardiness zone warmer than before spring flooding of rice fields. Compared New Jersey), University of Maryland Weed

SUBTERRANEAN CLOVERS 137 Specialist Ed Beste reported good reseeding in COMPARATIVE NOTES four consecutive years and no problems with stand loss from premature spring regrowth. White and arrowleaf clovers have proved to be Overwintering MT.BARKER plants sent out stolons better self-reseeding clovers than subclover in the across the soil surface to quickly re-establish a humid South because their seed is held in the air, good stand ahead of sweet corn plantings (19). giving them a better chance to harden (320). Beste believes the sandy loam soil with a sand Top reseeding contenders are balansa clover (see underlayer at his site is better for subclover than Up-and-Coming Cover Crops, p. 158.) and south- the heavier clay soils at the USDA Beltsville station ern spotted bur medic (see Southern Spotted Bur some 80 miles north, where hairy vetch usually Medic Offers Reseeding Persistence, p. 122). out-performs subclover as a killed organic mulch in While mid-season subclovers generally pro- transplanted vegetable systems.Winterkill reduced duced more dry matter and N than medics for the subclover stand on top of bedded rows one dryland cereal-legume rotations in Montana year of the comparison, yet surviving plants (314), they did not set seed when grown as sum- between the beds produced nearly as much mer annuals in the region. Summer growth con- biomass per square foot as did hairy vetch (1). tinued as long as moisture held up in trials there. Beste has worked with subclover at his Vegetative growth increased until frost, as cool, Salisbury, Md., site for several years, seeding veg- moist fall weather mimicks the Mediterranean etables in spring, early summer and mid-summer winter conditions where subclover thrives (316). into the killed or naturally dead cover crop CLARE is a cultivar of the subclover subspecies mulch. For three years, subclover at Beste’s sweet brachycalycinum.Compared with the more com- corn system comparison site yielded about 5,400 mon subspecies subterranean (SEATON PARK and lb. DM/A. Without added N, the subclover plots DALIAK), CLARE has vigorous seedlings, robust yielded as much sweet corn as conventional plots growth when mowed monthly and is said to tol- receiving 160 lb. N/A. Weed suppression also was erate neutral to alkaline soils. However, it appears better than in the conventional plots. He sprayed to be less persistent than other types (43). glyphosate on yellow nutsedge in fall to prevent Subclover,rye and crimson clover provided grass tuber formation by the grassy weed, the only weed control that was 46 to 61 percent better than weed that penetrated the subclover mulch (19). a no-cover/no-till system at two North Carolina Beste sprays paraquat twice to control sub- locations. Subclover topped the other covers in clover ahead of no-till, direct seeded zucchini in suppressing weeds in plots where no herbicides the first week of June. His MT.BARKER will set seed were used. None of the cover crop treatments and die back naturally at the end of June—still in eliminated the need for pre-emergent herbicides time to seed pumpkins, fall cucumbers, snap for economic levels of weed control (373). beans or fall zucchini planted without herbicides Subclover creates a tighter mat of topgrowth (19).Such a no-chemical/dying mulch/perpetually than vetch (19) or crimson clover (77). reseeding legume system is the goal of cultivar and system trials in California (346). SEED Seed production in subclovers normally is triggered by increasing day length in spring after the Cultivars. See Comparative Notes, above, and plant experiences decreasing fall day length Diversity of Types, Cultivars (p. 132). (346). This explains why spring-planted subclover in Montana tests produced profuse vegetative Seed sources. Adams-Briscoe, Ampac, Budd, growth,especially when fall rains began,but failed Kamprath, Kaufman, Peaceful Valley. See Seed to set any seed (316). Stress from drought and Suppliers (p. 166). heat also can trigger seed set.

138 MANAGING COVER CROPS PROFITABLY 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 biennial marginal area spring sown fall sown See charts, pp. 47 to 53, for ranking and management summary.

ithin a single season on even marginal- throughout the Midwest in the first half of this ly fertile soils, this tall-growing biennial century.Sweetclover is used as a cover crop most W produces abundant biomass and mod- commonly now in the Plains region,with little use erate amounts of nitrogen as it thrusts a taproot in California. and branches deep into subsoil layers. Given fertile soils and a second season, it lives up to its full Types potential for nitrogen and organic matter produc- Biennial yellow sweetclover can produce up to 24 tion. Early in the second year it provides new top inches of vegetative growth and 2.5 tons dry mat- growth to protect the soil surface as its roots ter/A in its establishment year. During the second anchor the soil profile. It is the most drought-tol- year, plants may reach 8 feet tall. Root mass and erant of forage legumes, is quite winter-hardy and penetration (to 5 feet) are greatest at the end of can extract from the soil then release phospho- dormancy in early spring, then gradually dissipate rus, potassium and other micronutrients that are through the season (365). otherwise unavailable to crops. A distinguishing sweetclover feature is bracts of Sweetclover thrives in temperate regions wher- tiny blooms through much of its second year. ever summers are mild. Annual sweetclovers White biennial sweetclovers are taller, more (HUBAM is the most well known) work best in the coarsely stemmed, less drought tolerant, and pro- Deep South, from Texas to Georgia. There, they duce less biomass in both the seeding and second establish more quickly than the biennial types and years.White types bloom 10 to 14 days later than produce more biomass in the seeding year in yellow, but bloom for a longer season. They southern regions. reportedly establish more readily in New York In this chapter,“sweetclover” refers to biennial (370). Tall, stemmy cultivars are better for soil types unless otherwise noted. improvement (91, 302, 351). Sweetclover was the king of green manures Both yellow and white sweetclover have culti- and grazing legumes in the South and later vars 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).

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

Marianne Sarrantonio can produce 7,500 to 9,000 lb. dry matter/A YELLOW SWEETCLOVER (Melilotus officinalis) (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. pound exists in bound form in the plant and poses no problem during grazing. However, Hot-weather producer. Sweetclover has the coumarin can cause internal injury to cattle when greatest warm-weather biomass production of they eat spoiled sweetclover hay or silage. any legume, exceeding even alfalfa (306). Annual sweetclover (M.alba var. annua) is not frost tolerant, but can produce up to 9,000 lb. dry Soil structure builder. Kansas farmer Bill matter/A over a summer after being oversown Granzow says sweetclover gives his soils higher into a grain crop or direct seeded with a spring organic matter, looser structure and better grain nurse crop. The best-known annual sweet- tilth (126). See Sweetclover: Good Grazing, Great clover cultivar is HUBAM, a name often used for all Green Manure (p. 142). HUBAM annual sweet- annual white sweetclover. While its taproot is clover also improved soil quality and increased shorter and more slender than that of its biennial yield potential in 1996 New York trials (371). cousins, it still loosens subsoil compaction. Compaction fighter. Yellow sweetclover has a BENEFITS determinate taproot root up to 1 foot long with extensive branches that may penetrate 5 feet to Nutrient scavenger. Sweetclover appears to aerate subsoils and lessen the negative effects of have a greater ability to extract potassium, phos- compaction on crops.White types have a strong phorus and other soil nutrients from insoluble tap root that is not determinate (125). minerals than most other cover crops. Root branches take in minerals from seldom-disturbed Inexpensive. Establishment costs of about soil horizons, nutrients that become available as $11/A are one-half to one-fifth that of other major the tops and roots decompose (302). legume cover crops. Research in Saskatchewan during a 34-year period showed that phosphorus (P) availability Drought survivor. Once established, sweet- increased in subsoil layers relative to surface lay- clover is the most drought tolerant of all cover ers, peaking at an 8-foot depth.Winter wheat and crops that produce as much biomass. It is espe- safflower, with deeper root systems than spring cially resilient in its second year,when it could do wheat, could tap the deep P buildup from the well in a dry spring during which it would be

140 MANAGING COVER CROPS PROFITABLY difficult to establish annual cover crops.The yel- An excessively dense stand will create spindly low type is less sensitive to drought and easier to stalks that don’t branch or root to the degree that establish in dry soils than the white type (125). plants do in normal seedings. Further, the plants will tend to lodge and lay over,increasing the risk Attracts beneficial insects. Blossoms attract of diseases. So for maximum effect of subsoil honeybees, tachinid flies and large predatory penetration or snow trapping, go with a lighter wasps, but not small wasps. seeding rate. Sweetclover produces 50 percent or more hard Widely acclimated. Self-reseeding sweetclover seed that can lie in soil for 20 years without ger- can be seen growing on nearly barren slopes,road minating. Commercial seed is scarified to break rights-of-way, mining spoils and soils that have this non-porous seedcoat and allow moisture to low fertility, moderate salinity or a pH above 6.0 trigger germination. If you use unscarified seed, (141). It also can tolerate a wide range of envi- check hardseed count on the tag and do not ronments from sea level to 4,000 feet in altitude, count on more than 25 percent germination from including heavy soil, heat, insects, plant diseases the hardseed portion. The need for scarification (91) and as little as 6 inches of rain per year. to produce an adequate stand may be over-rated, however. The process had no effect on germina- Livestock grazing or hay. If you need emer- tion in six years of field testing in North Dakota— gency forage, sweetclover has a first-year feed even when planting 70 percent hard seed still in value similar to alfalfa,with greater volume of less- seed pods (214). 1 1 er quality in the second year. Seed at a depth of /4 to /2 inch in medium to 1 heavy textured soils, and /2 to 1.0 inch on sandy MANAGEMENT soils. Seeding too deeply is a common cause of poor establishment. Establishment & Field Management Seed annual white sweetclover at 15 to 30 Sweetclover does well in the same soils as alfalfa. pounds per acre. Expect 70 to 90 lb. N/A from Loam soils with near-neutral pH are best. Like 4,000 to 5,000 lb. dry matter/A on well-drained, alfalfa, it will not thrive on poorly drained soils. clay loam soils with neutral to alkaline pH. For high yields, sweetclover needs P and K in the A press-wheel drill with a grass seed attach- medium to high range. Deficient sulfur may limit ment and a seed agitator is suitable for planting its growth (116). Use an alfal- sweetclover into a firm seed- fa/sweetclover inoculant. Winter-hardy and drought bed. If the seedbed is too In temperate areas of the loose to allow the drill to reg- Corn Belt, drill yellow sweet- tolerant, this biennial can ulate seeding depth, run the clover in pure stands at 8 to 15 produce up to 200 lb. N/A seed spouts from the grass lb./A or broadcast 15 to 20 and legume boxes to drop lb./A, using the higher rate in with good fertility and seed behind the double-disk dry or loose soils or if not rainfall. opener and in front of the incorporating. press wheels. Light, shallow In drier areas such as eastern harrowing can safely firm the North Dakota, trials of seeding rates from 2 to 20 seedbed and incorporate seed (141). lb./A showed that just 4 lb./A, broadcast or drilled, If your press-wheel drill has no legume box or created an adequate sole-crop stand for maximum grass-seed attachment, you can mix the legume yield.Recommended rates in North Dakota are 4 to and small grain seed. Reduce competition 6 lb./A drilled with small grains at small-grain plant- between the crops by seeding a part of the coming, 5 to 8 lb./A broadcast and harrowed (some- panion crop first, then seed a mix of the clover times in overseeding sunflowers),and 6 to 10 lb./A. seed and the balance of the grain seed at right broadcast without incorporating tillage (141). 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 Cyclo- companion wheat crop in four possible ways, planter with small furrow openers.Another 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. Second- them graze for several weeks, then disk year yellow sweetclover makes silage at initial 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

142 MANAGING COVER CROPS PROFITABLY Spring seeding provides yellow sweetclover no sweetclover is currently clipped in the first ample time to develop an extensive root system year (214). and store high levels of nutrients and carbohy- Top growth peaks in late summer as the plant’s drates necessary for over-wintering and robust main taproot continues to grow and thicken. spring growth. It grows slowly the first 60 days Second-year growth comes from crown buds that (116). Where weeds would be controlled by form about an inch below the soil surface.Avoid mowing, no-till spring seeding in small grain mowing or grazing of sweetclover in the six- to stubble works well. seven-week period prior to frost when it is build- Broadcast seeding for pure sweetclover stands ing final winter reserves. Root production practi- works in higher rainfall areas in early spring cally doubles between Oct.1 and freeze-up (125). where soil moisture is adequate for seven to 10 Sweetclover establishes well when sown with days after planting. No-till seeding works well in winter grains in fall, but it can outgrow the grain small grain stubble. in a wet season and complicate harvest. Frostseeding into winter grains allows a harvest of at least one crop during the life cycle of the Second-year management.After it breaks win- sweetclover and helps control weeds while the ter dormancy,sweetclover adds explosive and vig- sweetclover establishes. Apply sweetclover seed orous growth. Stems can reach 8 feet before before rapid stem elongation of the grain. Cut flowering, but if left to mature, the stems become grain rate about one-third when planting the woody and difficult to manage. Plants may grow crops together. extremely tall in a “sweetclover year” with high Sweetclover spring seeded with oats exhibited rainfall and moderate temperatures. poor regrowth after oat harvest in two years of a Nearly all growth the second year is topgrowth, Wisconsin study. To establish a sweetclover and it seems to come at the expense of root mass. cover crop in this way, the researchers found From March to August in Ohio, records show top- sweetclover did not fare well in years when the growth increasing tenfold while root production combine head had to be run low to pick up decreased by 75 percent (125, 365). All crown lodged oats. When oats remained upright (sacri- buds initiate growth in spring. If you want ficing some straw for a higher cut), sweetclover regrowth after cutting, leave plenty of stem buds grew adequately (330). on 6 to 12 inches of stubble. You increase the risk You can plow down spring-planted yellow of killing the sweetclover plant by mowing heav- sweetclover in late fall of the planting year to cash ier stands, at shorter heights, and/or at later in early on up to half its N contribution and a bit growth stages, especially after bloom (141). less than half its biomass. Before it breaks dormancy, sweetclover can Plant biennial sweetclover through late withstand flooding for about 10 days without summer where winters are mild, north through significant stand loss. Once it starts growing, Zone 6. Plant at least six weeks before frost so however, flooding will kill the plants (141). roots can develop enough to avoid winter heaving. See Sweetclover: Good Grazing, Great Green Killing Manure (p. 142). For best results ahead of a summer crop or fallow, kill sweetclover in the second year after seeding First-year management. Seeding year harvest when stalks are 6 to 10 inches tall (141, 302). or clipping is usually discouraged, because the Killing sweetclover before bud stage has several energy for first-year regrowth comes directly from benefits: 80 percent of the potential N is present; photosynthesis (provided by the few remaining N release is quick because the plant is still quite leaves), not root reserves (302). Seeding year clip- vegetative with a high N percentage in young ping before Aug. 15 in North Dakota can boost stalks and roots; and moisture loss is halted with- biomass production by 50 percent, but virtually out reducing N contribution. Sweetclover may

SWEETCLOVERS 143 regrow from healthy crowns if incorporated Pest Management before the end of dormancy.For optimum full-sea- Sweetclover is a rather poor competitor in its son organic matter contribution, mow prior to establishment year, making it difficult to establish blossom stage whenever sweetclover reaches 12 pure sweetclover in a field with significant weed to 24 inches high before final incorporation or pressure. termination (302). Mowing or grazing at bloom Sweetclover residue is said to be allelopathic can kill the plants (125). against stinkweed and green foxtail. Repeated In dryland areas,the optimum termination date mowing of yellow sweetclover that is then left to for a green manure varies with moisture condi- mature is reported to have eradicated Canada this- tions. In a spring wheat>fallow rotation in Saskat- tle. Letting sweetclover bloom and go to seed chewan, sweetclover incorporated in mid-June of dries out soil throughout the profile,depleting the a dry year provided 80 percent more N the fol- root reserves of weeds. lowing spring than it did when incorporated in Sweetclover weevil (Sitonia cylindricollis) is a early July or mid-July—even though it yielded up major pest in some areas, destroying stands by to a third less biomass at the June date. defoliating newly emerged seedlings. Long rota- Mineralization from sweetclover usually peaks tions can reduce damage, an important factor for about a year after it is killed.The potential rate of organic farmers who depend on sweetclover fer- N release decreases as plants mature and is affect- tility and soil improvements. In the worst years of ed by soil moisture content (112). an apparent 12 to 15-year weevil cycle in his area, In this study,the differences in N release were “every sweetclover plant across the countryside consistent in years of normal precipitation, but is destroyed,” according to organic farmer David were less pronounced. Little N mineralization Podoll, Fullerton, N.D. “Then the weevil popula- occurred in the incorporation year. Nitrogen tion crashes, followed by a few years where addition peaked in the following year, and has they’re not a problem,then they begin to rebuild.” been shown to continue over seven years fol- Cultural practices have not helped change the lowing yellow sweetclover (112). cycle, but planting early with a non-competitive In northern spring wheat areas of North nurse crop (flax or small grains) gives sweet- Dakota, yellow sweetclover is usually terminated clover plants the best chance to survive weevil in early June just at the onset of bloom, when it foraging, Podoll says. Efforts continue on his farm reaches 2 to 3 feet tall. This point is a compromise and other locations to establish a parasitic wasp between cover crop gain (in from a similar climate in dry matter and N) and water During its second season, Russia that will help to stabi- consumption. A quick kill lize the weevil population. from tillage or haying is more yellow sweetclover can Eric and Anne Nordell of expensive and labor-intensive grow 8 feet tall while north-central Pennsylvania than chemical desiccation, report that early spring plow- but it stops moisture-robbing roots penetrate 5 feet deep. down of their overwintered transpiration more quickly sweetclover gives them fewer (116). Herbicides that kill sweetclover include slug and grub problems on spring-planted crops 2,4-D, dicamba, glyphosate and paraquat (25), than later plowdown. They prefer to have the with the latter material offering quicker desicca- legume start a cover>fallow>cover sequence on tion than glyphosate (82). their certified organic farm.They overseed yellow Grazing is another way to manage second-year sweetclover into early crops in June, let it over- sweetclover before incorporation. Start early in winter, then plow it down. A slug-fighting bare the season with a high stocking rate of cattle to fallow period then precedes August-planted rye stay ahead of rapid growth. Bloat potential is and hairy vetch. The Nordells fit their cash slightly less than with alfalfa (116). crops around the cover crop rotation that best

144 MANAGING COVER CROPS PROFITABLY enhances soil fertility, texture and moisture and reduce the erosion potential after oilseed crops, suppresses weeds. See Full-Year Covers Tackle which leave little residue over winter (116). Tough Weeds (p. 38). Interplanting works with tall crops. A In a three-year Michigan trial of crop rotations Wisconsin researcher reported success drilling to decrease economic losses to nematodes, a sweetclover between the rows when corn was 6 yellow sweetclover (YSC)>YSC>potato sequence to 12 inches tall. Overseeding sweetclover into out-yielded other combinations of rye, corn, sweet corn works even better due to greater light Sorghum- sudangrass and alfalfa. Two years of penetration. clover or alfalfa followed by potatoes led to a yield Sweetclover overseeded into sunflowers at last response equivalent to application of a nemati- cultivation succeed about half the time, North cide for control of premature potato vine death Dakota trials show. Dry conditions or poor seed- (56). Legume-supplied N coupled with an overall to-soil contact were the main reasons for not get- nutrient balance and enhanced cation exchange ting a stand. A heavier seeding rate or earlier capacity from the cover crop are thought to be planting will tend to increase stand. Band-seeding involved in suppressing nematode damage (20). sweetclover over the row with an insecticide box at sunflower planting proved more successful in Crop Systems the trial. The method also permits between-row In the moderately dry regions of the central and cultivation (116). northern Great Plains,“green fallow”systems with Even though legume green manures in another water-efficient legumes can be substituted for North Dakota study used about 2.8 inches (rain- bare-ground or stubble mulch fallow. In fallow fall equivalent) more water than fallow,they led to years, no cash crop is planted with the intent of a 1-inch equivalent increase over fallow in soil recovering soil moisture, breaking disease or water content in the top 3 inches of soil the fol- weed cycles and maximizing yields of following lowing spring (9). cash crops. The retained One green fallow option is residue of “brown” fallow Sweetclover is the best planting yellow sweetclover lessens the erosion and evapo- with spring barley or spring ration of tillage-intensive “black producing warm-season peas. This is challenging, how- fallow,”but “green fallow” offers forage legume, even ever, because barley can be even more benefits in terms of overly competitive while herbi- soil biological life, biodiversity, topping alfalfa. cide compatibility is a concern beneficial insect habitat, possi- with the peas. ble harvestable crops and alternate forages. Fred Kirschenmann of Windsor, N.D., controls Rapeseed (Brassica campestris) is a summer spring weed flushes on his fallow after sunflow- annual cash crop in the dryland West that can ers with an initial shallow chisel plowing then a serve as a nurse crop for sweetclover. A rod weeder pass or two before planting sweet- Saskatchewan study of seeding rates showed opti- clover with a nurse crop of buckwheat or oats (or mum clover yield came when sweetclover was millet, if there is less soil moisture). He harvests sown at 9 lb./A and rapeseed was sown at 4.5 buckwheat, hoping for a 900 lb./A yield, then lets lb./A. The mixture allows an adequate stand of the clover grow and overwinter. In early summer, sweetclover that provides soil protection after the when he begins to see yellow blossoms, he disks low-residue rapeseed (203). the cover,lets it dry,then runs a wide-blade sweep Sole-cropped oilseed species (rapeseed, sun- plow just below the surface to cut apart the flower, crambe and safflower) require herbicides crowns. The biomass contribution of the sweet- for weed control. Many of these materials are clover fallow builds up organic matter, he says, in compatible with legumes, offering a post-emer- contrast to the black-fallow route of burning up gent weed-control option if the covers do not ade- organic matter to release N. Preventing humus quately suppress weeds. The covers greatly depletion holds back the dreaded kochia weed.

SWEETCLOVERS 145 In higher-rainfall temperate areas,overseed veg- clovers with other tap-rooted “resident vegeta- etables with yellow sweetclover in early or mid- tion,”Mazour says. summer. A one-row cultipacker greatly improves germination of overseeded legumes on the COMPARATIVE NOTES Nordell farm in their fresh vegetable operation near Trout Run, Pa. If in-row weeds are under con- Sweetclover and other deep-rooted biennial and trol and a crop canopy is forming, the clover’s perennial legumes are not suited for the most slow start should prevent competition with the severely drought-prone soils, as their excessive crop. Heavy late-season moisture could cause soil moisture use will depress yield of subsequent excessive clover growth if you have no means to wheat crops for years to come (128). mow between the rows, the Nordells found. When planting sweetclover after wheat har- They will sometimes mix yellow sweetclover vest, weeds can become a problem. An organic with white and red clover for June overseeding farmer in northeastern Kansas reports that to kill into early crops. Seeding rate is 15, 4 and 6 lb./A, cocklebur, he has to mow lower than the sweet- respectively. The red and white clovers regrow clover can tolerate. Annual alfalfa can tolerate in late summer of Year 2 after the yellow sweet- low mowing (161). clover has been clipped After 90 days’growth in a twice,once in late May then Sweetclover tolerates a wide North Dakota dryland again at full-bloom in mid- legume comparison, a June July. range of harsh environments, planting of yellow sweet- In temperate areas you poor soils and pests. clover produced dry matter can overseed spring broc- and N comparable to alfalfa coli with HUBAM annual and lespedeza (Lespedeza sweetclover, let the cover grow during summer, stipulacea Maxim). Subclover, fava beans (Vicia then till it in before planting a fall crop. faba) and field peas had the best overall N-fixing Alternatively, you can allow it to winterkill for a efficiency in the dryland setting because of quick thick, lasting mulch. early season growth and good water use efficiency (270). Other Options First-year forage has the same palatability and SEED feeding value as alfalfa, although harvest can reduce second-year vigor. Second-year forage is of Cultivars. Yellow cultivars include MADRID, lower quality and becomes less palatable as plants which is noted for its good vigor and production, mature, but may total 2 to 3 tons per acre (91). and its relative resistance to fall freezes. GOLDTOP Growers report seed yield of 200 to 400 lb./A has excellent seedling vigor, matures two weeks in North Dakota. Minimize shattering of seedpods later, provides larger yields of higher quality for- by swathing sweetclover when 30 to 60 percent age and has a larger seed than MADRID (302). of its pods are brown or black. Pollinating insects Yellow common and YUKON joined GOLDTOP are required for good seed yield (141). and MADRID—all high-coumarin types—as the Hard seed that escapes harvest will remain in highest yielding cultivars in a six-year North the soil seed bank, but organic farmer Rich Dakota test (215). Mazour of Deweese, Neb., sees that as a plus. Leading white biennial cultivars are DENTA, A 20- to 30-percent stand in his native grass pas- POLARA and ARCTIC.POLARA and ARCTIC are adapted tures comes on early each spring, giving his cattle to very cold winters. Best for grazing are the early grazing. Once warm-season grasses start to lower-producing, low-coumarin cultivars DENTA grow, they keep the clover in check. In tilled and POLARA (white) and NORGOLD (yellow). fields,modern sweep cultivators and residue-management tillage implements take care of sweet- Seed sources. Widely available.

146 MANAGING COVER CROPS PROFITABLY 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

See charts, pp. 47 to 53, for ranking summer annual perennial and management summary.

hite clovers are a top choice for “living for forage. The best of 36 varieties tested in mulch” systems planted between rows north-central Mississippi for cover crop use W of irrigated vegetables or trees. They were ARAN,GRASSLAND KOPU and KITAOOHA.These are persistent, widely adapted perennial nitrogen ranked high for all traits tested, including plant producers with tough stems and a dense shallow vigor, leaf area, dry matter yield, number of seed- root mass that protects soil from erosion and sup- heads,lateness of flowering and upright stems to presses weeds. Depending on the type, plants prevent soil contact. Ranking high were ANGEL grow just 6 to 12 inches tall, but thrive when GALLARDO,CALIFORNIA LADINO and widely used mowed or grazed.Once established,they stand up LOUISIANA S-1 (321). well to heavy field traffic and thrive under cool, White clover performs best when it has plenty moist conditions and shade. of lime, potash, calcium and phosphorus, but it tolerates poor conditions better than most Three types: Cultivars of white clover are clovers. Its perennial nature depends on new grouped into three types by size. The lowest plants continually being formed by its creeping growing type (Wild White) best survives heavy stolons and, if it reaches maturity,by reseeding. traffic and grazing. Intermediate sizes (Dutch White clover is raised as a winter annual in the White, New Zealand White and Louisiana S-1) South, where drought and diseases weaken flower earlier and more profusely than the larger stands. It exhibits its perennial abilities north types, are more heat-tolerant and include most of through Hardiness Zone 4. The short and inter- the economically important varieties. The large mediate types are low biomass producers, while (Ladino) types produce the most N per acre of the large ladino types popular with graziers can any white types, and are valued for forage quality, produce as much biomass as any clover species. especially on poorly drained soil.They are generally less durable, but may be two to four times BENEFITS taller than intermediate types. Intermediate types of white clover include Fixes N. A healthy stand of white clover can pro- many cultivated varieties, most originally bred duce 80 to 130 lb. N/A when killed the year after

WHITE CLOVER 147 establishment. In established stands, it also may Fits long, cool springs. In selecting a fall-seed- provide some N to growing crops when it is ed N-producer, consider white clover in areas managed as a living mulch between crop rows. with extended cool springs. MERIT ladino clover Because it contains more of its total N in its roots was the most efficient of eight major legumes than other legumes, partial tilling is an especially evaluated in a Nebraska greenhouse for N2 fixed effective way to trigger N release. The low C:N per unit of water at 50 F.Ladino, hairy vetch and ratio of stems and leaves causes them to decom- fava beans (Vicia faba) were the only legumes pose rapidly to release N (82). shown to fix more than 50 percent of their total N output at the 50 F temperature. Fava bean’s N Tolerates traffic. Wherever there’s intensive fixation rate declined during the period 42 to 105 field traffic and adequate soil moisture, white days after planting as ambient temperature clover makes a good soil covering increased, while ladino’s fixa- that keeps alleyways green. It Tough, low-growing tion rate increased at each of reduces compaction and dust four sample dates (273). while protecting wet soil against and shade tolerant, trauma from vehicle wheels. this perennial is often Overseeded companion crop. White clover converts vulnerable Whether frostseeded in early bare soil into biologically active used as a living mulch spring into standing grain, soil with habitat for beneficial in vegetable systems. broadcast over vegetables in organisms above and below the late spring or into sweet corn in soil surface. early summer, white clover germinates and establishes well under the primary Premier living mulch. Their ability to grow in crop. It grows slowly while shaded as it develops shade, maintain a low profile, thrive when repeat- its root system, then grows rapidly when it edly mowed and withstand field traffic makes receives more light. intermediate and even short-stemmed white clovers ideal candidates for living mulch systems. MANAGEMENT To be effective, the mulch crop must be managed so it doesn’t compete with the cash crop for light, Establishment & Fieldwork nutrients and moisture.White clover’s persistence Widely adapted. White clover can tolerate wet in the face of some herbicides and minor tillage is soil—even short flooding—and short dry spells, used to advantage in these systems (described and survives on medium to acid soils down to pH below) for vegetables, orchards and vineyards. 5.5. It volunteers on a wider range of soils than most legumes, but grows better in clay and loam Value-added forage. Grazed white clover is soils than on sandy soils (91). Ladino prefers highly palatable and digestible with high crude sandy loam or medium loam soils. protein (about 28 percent), but it poses a bloat Use higher seeding rates (5 to 9 lb./A drilled, 7 risk in ruminants without careful grazing manage- to 14 lb./A broadcast) when you overseed in ment practices. adverse situations caused by drought, crop residue or vegetative competition. Drill 4 to 6 Spreading soil protector. Because each white lb./A when mixing white clover with other clover plant extends itself by sending out root-like legumes or grasses to reduce competition for stolons at ground level, the legume spreads over light, moisture and nutrients. time to cover and protect more soil surface. Frostseeding of small-seeded clovers (such as Dropped leaves and clipped biomass effectively alsike and white) should be done early in the mulch stolons, encouraging new plants to take morning when frost is still in the soil. Later in the root each season.Reseeding increases the number day,when soil is slippery,stand establishment will of new plants if you allow blossoms to mature. be poor.Frostseed early enough in spring to allow

148 MANAGING COVER CROPS PROFITABLY for several freeze-thaw cycles. Make sure warm- soil 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- Marianne Sarrantonio fixing bacteria persist longer in cooler soils, with WHITE CLOVER (Trifolium repens— even volunteer wild white clover leaving enough intermediate type) behind for up to three years (91). Mowing no lower than 2 to 3 inches will keep white clover healthy.To safely overwinter white problems.Protect against pest problems by select- clover, leave 3 to 4 inches (6 to 8 inches for taller ing resistant cultivars, rotating crops, maintaining types) to prevent frost damage. soil fertility and employing proper cutting schedules (302). Killing Thorough uprooting and incorporation by chisel Crop Systems or moldboard plowing, field cultivating, undercut- Living mulch systems. As a living mulch, white ting or rotary tilling, or—in spring—use of a suit- clover gives benefits above and below ground able herbicide (glyphosate, for example) will while it grows between rows of cash crops, pri- result in good to excellent kill of white clover. marily in vegetables, orchards and vineyards. Extremely close mowing and partial tillage that Living mulch has not proved effective in agro- leaves any roots undisturbed will suppress, but nomic crops to this point. To receive the multiple not kill, white clover. benefits, manage the covers carefully throughout early crop growth—to keep them from compet- Pest Management ing with the main crop for light, nutrients, and Prized by bees. Bees work white clover blos- especially moisture—while not killing them. soms for both nectar and pollen. Select insect- Several methods can do that effectively. management measures that minimize negative impact on bees and other pollinators. Hand mowing/in-row mulch. Farmer Alan Matthews finds that a self-propelled 30-inch Insect/disease risks. White clovers are fairly tol- rotary mower controls a clover mix between erant of nematodes and leaf diseases, but are sus- green pepper rows in a quarter-acre field.He uses ceptible to root and stolon rots. Leading insect 40-foot wide, contour strip fields and the living pests are the potato leafhopper (Empoasca fabae), mulch to help prevent erosion on sloping land meadow spittlebug (Philaenis spumarius), clover near Pittsburgh, Pa. In his 1996 SARE on-farm leaf weevil (Hypera punctata), alfalfa weevil research, he logged $500 more net profit per acre (Hypera postica) and Lygus bug (Lygus spp.). on his living mulch peppers than on his conven- If not cut or grazed to stimulate new growth, tionally produced peppers (207, 208). the buildup of vegetation on aged stolons and Matthews mulches the transplants with hay, 12 stems creates a susceptibility to disease and insect 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. Partial rotary tillage. In a New York evaluation The mix is 50 percent white Dutch clover,30 per- of mechanical suppression, sweet corn planting cent berseem clover, and 20 percent HUIA white strips 20 inches wide were rotary tilled June 2 clover, which is a bit taller than the white Dutch. into white clover. While mowing (even five times) He mows the field in fall,then broadcasts medium didn’t sufficiently suppress clover, partial rotary red clover early the next spring to establish a hay tilling at two weeks after emergence worked well. field and replace the berseem, which is not win- A strip of clover allowed to pass between the terhardy (207, 208). tines led to ample clover regrowth.A surge of N New Zealand white clover provided good within a month of tilling aided the growing corn. weed control for winter squash in the wetter of The loss of root and nodule tissue following stress two years in a New York from tillage or herbicide trial. It was used in an Healthy stands can produce shock seems to release N experimental non-chemical from the clover. Leaf smut system relying on over-the- 80 to 130 lb. N/A when killed caused less problem on the row compost for in-row the year after establishment. living-mulch corn than on weed control. Plants were the clean-cultivated check seeded into tilled strips 16 plot (133). inches wide spaced 4 feet apart. Poor seed establishment and lagging clover growth in the drier Crop shading. Sweet corn shading can hold year created weed problems, especially with white clover in check when corn is planted in 15- perennial competitors.The living mulch/compost inch rows and about 15 inches apart within the system yielded less than a conventionally tilled row. This spacing yielded higher corn growth and fertilized control both years, due in part to rates, more marketable ears per plant and higher delayed crop development from the in-row com- crop yields than conventional plots without post (226). clover in an Oregon study. Corn was planted into The research showed that in dry years,mowing tilled strips 4 to 6 inches wide about the same alone won’t suppress a living mulch enough to time the clover was chemically suppressed. keep it from competing for soil moisture with Adapted row-harvesting equipment and hand- crops in 16-inch rows.Further,weeds can be even picking would be needed to make the spacing more competitive than the clover for water dur- practical (105). ing these dry times (226). Unsuppressed white Dutch clover established at A California study showed that frequent mowing asparagus planting controlled weeds and provided can work with careful management. A white clover N over time to the asparagus in a Wisconsin study, cover reduced levels of cabbage aphids in harvest- but reduced yield significantly. Establishing the ed broccoli heads compared with clean-cultivated clover in the second year or third year of an aspara- broccoli. The clover-mulched plants, in strip-tilled gus planting would be more effective (251). rows 4 inches wide, had yield and size comparable to clean cultivated rows. However, only intensive Other Options irrigation and mowing prevented moisture compe- Seed crop should be harvested when most seed tition. To be profitable commercially, the system heads are light brown, about 25 to 30 days after would require irrigation or a less thirsty legume, as full bloom. well as field-scale equipment able to mow between Intermediate types of white clover add protein several rows in a single pass (67). and longevity to permanent grass pastures with- Chemical suppression is difficult. An appli- out legumes.Taller ladino types can be grazed or cation rate that sets back the clover sufficiently harvested. Living mulch fields can be overseeded one year may be too harsh (killing the clover) or with grasses or other legumes to rotate into pas- not suppressive the next year due to moisture, ture after vegetable crops, providing IPM options temperature or soil conditions. and economic flexibility.

150 MANAGING COVER CROPS PROFITABLY COMPARATIVE NOTES • Ladino and alsike are the best hay-type legumes on poorly drained soils. • White clover is less tolerant of basic soils • Spring growth of fall-seeded white clover above pH 7 than are other clovers. begins in mid-May in the Midwest, about the • In a Wisconsin comparison, ladino clover bio- same time as alfalfa. mass was similar to mammoth red clover when spring-seeded (330). Seed sources. Widely available. • White clover stores up to 45 percent of its N contribution in its roots, more than any other major legume cover crop.

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

See charts, p. 47 to 53, for ranking area of primary utility viable during mild, moist seasons and management summary.

pecialty vetches such as woollypod and pur- medic and LANA, for example. They plant the mix ple vetch (Vicia benghalensis) are faster- in alternate alleyways to save on seeding costs Sgrowing alternatives to hairy vetch (Vicia and reduce moisture competition, while ensuring villosa) in Hardiness Zone 7 and warmer. sufficient cover that they can mow or disk. LANA’s Requiring little or no irrigation as a winter cover climbing tendency (even more so than purple or in these areas,they provide dependable,abundant common vetch) and abundant biomass can N and organic matter, as well as excellent weed become problems in vineyards and young suppression. orchards,but can be readily managed with regular Many growers of high-value crops in California monitoring and timely mowing. rely on one or more vetch species as a self-reseed- In Zone 5 and colder and parts of Zone 6,wool- ing cover crop, beneficial insect habitat and lypod vetch can serve as a winterkilled mulch— mulch. They can mow the vetch during winter or as a quick, easy-to-mow spring cover—for and in late spring after it reseeds. weed control and N addition to vegetable trans- Some vineyard managers seed LANA woollypod plants. It’s a good choice as an overwintering vetch each year with oats or as part of a legume cover before or after tomato crops in Zone 6 mix—common vetch, subterranean clover, a and warmer. A study in California showed that

WHOOLLYPOD VETCH 151 LANA provided the most N and suppressed the Smother crop. Woollypod’s dense spring most weeds during two consecutive but distinctly growth smothers weeds and also provides some different growing seasons, compared with purple allelopathic benefits. Of 32 cover crops in a repli- vetch and other legume mixtures (342, 343). cated study at a California vineyard, only LANA completely suppressed biomass production of BENEFITS the dominant winter annual weeds such as chickweed, shepherd’s purse, rattail fescue and annual N Source. A first-year, overwintering stand of ryegrass (351). woollypod vetch easily will provide more than 100 pounds of N per acre in any system when Beneficial habitat. Woollypod vetch attracts allowed to put on spring growth. The popular many pollinators and beneficial insects. In some LANA cultivar starts fixing N in as little as one week orchards, these beneficials move up into the tree after emergence. canopy by late spring, so you can mow the floor LANA can contribute as much as 300 pounds of cover after it reseeds and not worry about loss of N its first year or two, given adequate moisture beneficial habitat (142). and warm spring growing conditions (219, 324). Fall-planted LANA incorporated before a corn crop MANAGEMENT can provide a yield response equivalent to 200 lb. N/A, a California study showed (219). Similar Establishment & Fieldwork results have been seen in tomato research in Woollypod does well on many soil types—even California (324). In western Oregon, a yield poor, sandy soil—and tolerates moderately acidic response equivalent to 70 lb. N/A for sweet corn to moderately alkaline conditions. It’s well- has been observed (87). adapted to most orchard and vineyard soils in California (351). Plenty of soil-building organic matter. It establishes best in recently tilled, nutrient- Woollypod typically produces more dry matter deficient fields (5). Tillage helps enhance the than any other vetch. LANA shows better early reseeding capability of vetches (44). LANA woolly- growth than other vetches, even during cool late pod vetch hasn’t done as well in some no-till sys- fall and winter weather in tems as it was expected to. Zone 7 and warmer. LANA Woollypod vetch is often Given adequate moisture, shows explosive growth in however, broadcasting LANA early spring in the Pacific used in mixes in California even at low to moderate Northwest (87) and in late orchards and vineyards. rates—and with light incor- winter and early spring in poration—can give satisfac- California when moisture is tory results from fall adequate. It can provide up to 8,000 lb. DM/A, seedings,especially if the stand is allowed to grow which breaks down quickly and improves soil through mid-spring. If your goal is to shade out structure (44, 219, 324). competition quickly, however, broadcast at medium to high rates and incorporate lightly. Frost protectant. Some orchard growers have You might not recognize the emerging plant found that keeping a thick floor cover before the without its characteristic multiple leaflets, says blossom stage can help prolong a perennial Glenn Anderson.“You should spot it within two crop’s dormant period by up to 10 days in weeks of planting, three at the latest, depending spring.“This reduces the risk of early frost dam- on temperature and soil conditions. Even at 6 age (to the blossoms, by delaying blossoming) inches,it’ll still look spindly.It won’t really leaf out and lengthens the blossoming period of my until late winter and early spring, when more almond trees,” notes almond grower Glenn aggressive growth kicks in.” That may continue Anderson, Hilmar, Calif. until maturity in mid- to late May.

152 MANAGING COVER CROPS PROFITABLY 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 distur- bance. He cautions against using a rotary tiller, which can pulverize the soil and reduce its water- holding capacity (167). Bartolucci prefers to drill rather than broadcast cover crops, saving on seed costs and ensuring seed-to-soil contact. He recommends the eco-

nomical, alternate row planting that also ensures SearsElayne easy access for pruning grape vines. WOOLLYPOD VETCH (Vicia villosa ssp. Don’t wait too long in fall to seed woollypod dasycarpa) 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 ing adequate moisture for your primary crop. In of central California,germination will be poor and wet environments such as western Oregon, how- the stand disappointing. Seed too early, though, ever, LANA vetch can retard spring soil drying and and you miss the early moisture benefit of the seedbed preparation for summer crops (87). Central Valley’s fog season (5) and will need to Woollypod responds well to mowing,as long as irrigate more before the rainy season (168). you keep the stand at least 5 inches tall and avoid Regardless of your planting method,seed wool- mowing during the two-month period just before lypod vetch into moist soil or irrigate immediate- it reseeds. “I can mow as late as mid-March and ly after seeding to help germination (219). If still see good reseeding,”says Glenn Anderson, an irrigation is an option but you want to conserve organic almond grower in California’s Central water costs,try seeding just before a storm is fore- Valley. “After that, I may mow if I want to prevent cast, then irrigate if the rain misses you. some frost damage, but I know I’ll lose some of the vetch through reduced reseeding.” Spring planting. Planted in early spring, woolly- Anderson usually mows the floor cover once or pod vetch can provide plowdown N by Memorial twice before mid-March and after it reseeds. He Day for a summer annual cash crop in the cuts in the direction of prevailing winds—which Northeast (300). can be on a diagonal to his tree rows—to facilitate air movement throughout the orchard, especially Mowing & Managing when he anticipates moist air heading his way. Woollypod vetch can survive freezing conditions In vineyards,“high chopping” legume mixes to for days, but severe cold can markedly reduce its a 12-inch height can help keep them from trellis- dry matter and N production (170, 219). ing over vine cordons. In vineyards without In most cases, main challenges for an estab- sprinklers for frost protection, some growers lished woollypod vetch stand include managing incorporate legume mixes in spring, before the its abundant growth and viny tendrils and ensur- soil becomes too dry for disking. Where sprin-

WOOLLYPOD VETCH 153 klers are used, the covers might be allowed to about 10 percent of the resident vegetation, he grow for a longer period and provide additional notes. Subclovers and other legumes he intro- N. Timing is important when disking, however, duced have become more prominent. Those as you don’t want to make equipment access legumes may have better self-reseeding capability difficult or compact soil during wet spring than LANA, other growers note (168). conditions (167). Given the high dry matter production from Pest Management woollypod vetch when it’s allowed to grow at Woollypod vetch outcompetes weeds and will least until late March, two or three diskings or quickly resolve most weed problems if seeded at mowings will encourage rapid decomposition. high rates. Woollypod also provides some Power spaders can reduce soil compaction when allelopathic benefits. A root exudate can reduce incorporating vetches in spring conditions, com- growth in some young grasses, lettuces and peas, pared with heavier disk harrows (350). however. Hard seed carryover can cause LANA to become Moisture concerns. Many orchard and vineyard a weed in subsequent cash crops and vineyards, growers find it helpful to drip irrigate tree or vine however (55). Its strong climbing ability can rows if they are growing an aggressive cover crop cover grape vines or entwine sprinklers. In such as LANA between the rows orchards,it’s fairly easy to cut or for the first time. In California LANA woollypod vetch pull Lana vines out of the vineyards where irrigation isn’t canopy of young trees. Mowing used, a few growers report that shows explosive growth or “high chopping” may be vines seem to lose vigor faster in early spring in the needed, especially in vineyards, when grown with cover crops. even though this can reduce Others haven’t observed this Pacific Northwest. LANA’s reseeding rate. effect.After a few years of grow- Insects pests aren’t a major ing leguminous covers, many find that their soil is problem with woollypod vetch, in part because it holding moisture better and they need less water attracts lady beetles, lacewings, minute pirate to make the system work. bugs and other beneficials insects that help keep pests in check. Reseeding concerns. Vetch mixtures often fail LANA can be a host of Sclerotinia minor, a soil- to reseed effectively, especially if they have been borne pathogen that causes lettuce drop, a fungal mowed at the wrong time or soil fertility is high. disease affecting lettuce, basil and cauliflower Some vineyard managers expect low persistence crops. In a California study involving cover crops and reseed a vetch mix in alternate rows every that were deliberately infected with S. minor, the fall, or reseed spotty patches. pathogen levels were associated with higher let- Regardless of mowing regime, LANA’s persis- tuce drop incidence the summer after Lana had tence as a self-reseeding cover diminishes over been incorporated, but wasn’t as problematic the time, and other resident vegetation starts to take following year. Woollypod vetch probably isn’t a over. That’s a sign that the cover’s water-holding, good choice if you’re growing crops susceptible fertility- and tilth-enhancing benefits have kicked to this pathogen. in, says Glenn Anderson. It’s natural to expect a change in the resident Other Options vegetation over time, observes Anderson. After a Seed. Woollypod vetch is a prolific seed few years of reseeding itself—and providing producer, but its pods are prone to shattering. abundant dry matter and nitrogen—the LANA he You can increase seed harvest by raking the had clear seeded at low rates between orchard field (without mowing, if possible) to gather rows on half his acreage eventually diminished to the crop into windrows for curing, before

154 MANAGING COVER CROPS PROFITABLY combining with a belt-type rubber pickup •LANA shows more early growth than common attachment (350). vetch, although both increase their biomass dramatically by midspring (168). Forage. Like most vetches, LANA is a somewhat •LANA and purple vetch are more cold-sensitive bitter yet palatable forage when green, and the than common vetch or hairy vetch. Once estab- palatability increases with dryness (350). It is a lished, LANA can tolerate early frosts for a few nutritious forage for rangeland use (350). days (especially if the temperature doesn’t fluc- For hay, it is best cut in full bloom.The leaves tuate widely or with some snow cover) and is dry rapidly and swaths can be gathered within a hardier than purple vetch, which is more sus- day or two (350). ceptible to early spring dieback (114). •LANA flowers about three weeks earlier than COMPARATIVE NOTES purple vetch and has a better chance of setting seed in dryland conditions (219). • Woollypod has slightly smaller flowers than •LANA and LANA mixes suppress weeds better hairy vetch, and its seeds are more oval than than purple vetch (114). the nearly round seeds of hairy vetch. LANA also has a higher proportion of hard seed than Seed sources. Widely available in the West, hairy vetch (351). including Ampac, Harmony, Lohse Mill and Peaceful Valley.See Seed Suppliers (p. 166).

WOOLLYPOD VETCH 155 APPENDIX A TESTING COVER CROPS ON YOUR FARM by Marianne Sarrantonio

To find your best cover crops, you needn’t or half-acre plots may be feasible,especially if oth- become Dr. Science or devote your life to ers in your area use similar species. research.It’s not hard to set up valid,on-farm tests If you use field-scale machinery, establish field- and make observations. Follow these steps: length plots. For row crops, use plots at least four rows wide, or your equipment width. Keep in A. Narrow your options. Aim for a limited-scale mind the subsequent crop’s management. trial of just two to five species or mixtures. You can test the best one or two in a larger trial the D. Design an objective trial. Plots need to be as next year. uniform as possible, randomly selected for Unsure of the niche? Start with small plots sep- each option you’re testing, and replicated (at arated from cropped fields and plant over a range least two or three plots for each option). of dates, under optimal soil and weather condi- If parts of the field have major differences tions. (such as poorer drainage or weedy spots), put If you’re sure of the niche and have just two or blocks of plots together so each treatment has three covers to try, put the trial right in your equal representation in each field part, or avoid cropped fields, using a similar seedbed prepara- those areas for your trial. tion. This method provides rapid feedback on Label each plot and make a map of the trial area. how the cover crops fit into your cropping system. Keep in mind management-related variables E. Be timely. Regard the trial as highly as could cause subpar results for an otherwise ade- any other crop. Do as much or as little field quate cover. preparation as you would for whole fields, and at an appropriate time. B. Order small seed amounts. Many compa- If possible, plant on two or more dates at least nies provide 1- to 10-pound bags if you give them two weeks apart. In general, seed winter annuals advance notice. If 50-pound bags are the only at least six weeks before a killing frost.Wheat and option, arrange to share it with other growers. rye can be planted later,although that will reduce Don’t eliminate a species just because seed the N-scavenging significantly. price seems high. If it works well, it could trim other costs. You could consider growing your F. Plant carefully. If seeding large plots with own seed eventually, and perhaps even selling it tractor-mounted equipment, calibrate your seed- locally. ing equipment for each cover. This can prevent Be sure to obtain appropriate inoculants if failures or performance differences due to incor- you’ll be testing legumes, which require species- rect seeding rates. Keep a permanent record of specific rhizobial bacteria so the cover can cap- drill settings for future reference. ture and “fix”N efficiently.See Nodulation: Match A hand-crank or rotary spin seeder works well Inoculant to Maximize N (p. 92). for small plots getting less than five pounds of seed.Weigh seed for each plot into a separate con- C. Determine plot sizes. Keep them small tainer. 1 lb./A is about equivalent to 1 gram/100 enough to manage, yet large enough to yield ade- sq. ft., and 1 pound equals 454 grams. quate and reliable data. Plots a few rows wide by Put half the seed in the seeder and seed 50 to 100 feet could suffice if you grow vegetables smoothly as you walk the length of the field and for market. If you have 10 or more acres, quarter- back, with a little overlap in the spread pattern.

156 MANAGING COVER CROPS PROFITABLY Then seed the remainder while walking in per- Assess performance by asking some of the pendicular directions so you crisscross the plot in questions you answered about the cover niche a gridlike pattern. (see Selecting the Best Cover Crops for your If broadcasting by hand, use a similar distribu- Farm, p. 12). Also ask if a cover: tion pattern.With small seed, mix in sand or fresh • was easy to establish and manage cat litter to avoid seeding too much at a time. • performed its primary function well • avoided competing excessively with the pri- G. Collect data. Start a trial notebook or binder mary crop for data and observations. • seemed versatile Management information could include: • is likely to do well under different conditions • field location • fits your equipment and labor constraints • field history (crops, herbicides, amendments, • provides options that could make it even unusual circumstances, etc.) more affordable • plot dimensions In year two, expand the scale. Test your best- • field preparation and seeding method performing cover as well as a runner-up. With • planting date and weather conditions field crops, try one-acre plots; stick with smaller • rainfall after planting plots for high-value crops. Also try any options • timing and method of killing the cover crop that might improve the cover stand or its benefits. • general comments. Entries for the major cover crops in this book include some management tips that can help. Growth data for each plot might include: Record your observations faithfully. • germination rating (excellent, OK, poor, etc.), seven to 14 days after seeding I. Fine-tune and be creative. Odds are, you • early growth or vigor rating, a month after won’t be completely satisfied with one or more establishment details of your “best” cover. You might need to • periodic height and ground cover estimates, sacrifice some potential benefits to make a before killing or mowing cover work better in your farm system. For • periodic weed assessments example, killing a cover earlier than you’d like • a biomass or yield rating will reduce the amount of biomass or N it Also rate residue before planting the next crop. provides, but could ensure you plant summer Rate survival of winter annuals in early spring as crops on time. they break dormancy and begin to grow. If you In most cases, fine-tuning your management plan to mow-kill an annual, log an approximate also makes it more affordable.Lowering a seeding flowering date. Regrowth could occur if most of rate or shifting the seeding date also could reduce the crop is still vegetative. the tillage needed. Narrower rows might hinder Rate overall weather and record dates such as establishment of an overseeded legume but first frost. Note anything you think has a bearing reduce weeds and bump up the cash crop yield. on the outcome, such as weed infestations. Finding a regionally adapted variety of a given If time allows, try killing the cover crops and species could simplify management—but also continuing your expected rotation, at least on a might have you looking around for a better cash small scale.You might need hand tools or a lawn crop variety. mower. Use field markers to identify plots. Don’t expect all of a cover’s benefits to show up in yearly economic analyses.Some benefits are H. Choose the best species for the whole hard to assess in dollars. farm system. Not sure which covers did best? When talking to other farmers, seed suppliers Whatever you found, don’t be satisfied with only and agricultural experts, tell them about your a single year’s results. Weather and management cover cropping experiences and ask for sugges- will vary over time. tions and ideas. Your best covers may seem

TESTING COVER CROPS 157 unbeatable. But there could be an up-and-com- year.This section offers enough tips to start testing species or management technique you ing cover crops. haven’t thought of testing. See Up-and-Coming You also can collaborate with others in your Cover Crops (p. 158) for a few examples. region to pool resources and share findings. Overwhelmed? You needn’t be. Initiative and There’s a good chance others in your area could common sense—traits you already rely on—are benefit from your cover cropping wisdom! fundamental to any on-farm testing program. As [Adapted from Northeast Cover Crop a grower, you already test varieties, planting Handbook by Marianne Sarrantonio, Rodale dates and other management practices every Institute, 1994.]

APPENDIX B UP-AND-COMING COVER CROPS

We chose the major cover crops in this book for Australia Department of Agriculture. A newer their range of benefits, reliability, availability and cultivar, BOLTA, was tested in California and Texas wide adaptability. They’re not the only cover in 1997. crops to choose from, of course. Here are a few While PARADANA seed matures slightly earlier others you might want to consider,either for their than crimson clover, it often does not produce as regional appeal or because they show strong much biomass. But PARADANA can reseed for sever- potential once seed becomes readily available. al years, due to its relatively high amount of hard seed. It has volunteered back for four years fol- Balansa clover lowing maturation of a seed crop in 1993 in Identified as a promising new cover crop in Senatobia,Miss.,and has reseeded successfully for Mississippi research, balansa clover (Trifolium at least two years in no-till systems at several other balansae) is a small-seeded annual legume with locations in Alabama, Georgia and Mississippi. superior reseeding potential compared with Neither TIBBEE nor AU ROBIN crimson clover other legumes, including crimson clover. reseeded for more than one year at any location in Well-adapted to a wide range of soil types, bal- those tests. It’s too soon to say how well balansa ansa performs particularly well on silty clay soil clover reseeds after tillage, but the small seeded with a pH of about 6.5. It does not do well on clover probably can’t stand being buried too highly alkaline soils (18). It appears to be hardy deeply. throughout Zone 7A and is considered marginal Balansa is a bit less likely than crimson clovers in Zone 6B. to host root-knot nematodes (Meloidogyne incog- Balansa clover seed is quite small, so the seed- nita,race 3).In research by Gary Windham,USDA- ing rate is only 10 lb./A. The seed is expensive ARS, Starkville, Miss., balansa had egg mass index and not widely available, however. It is produced scores between 2.3 and 2.9 on a scale from 1 to commercially only in Australia at this time.Balansa 5. For comparison, a very resistant white clover clover requires a relatively rare inoculant, desig- being readied for release has a 1.5 score, most nated “Trifolium Special #2” by Liphatech, Inc., crimson clovers score between 3 and 3.5 and manufacturer of “Nitragin” brand inoculants. (See very susceptible crops like REGAL white clover Appendix D, Seed Suppliers, p. 166, for contact score a 5. information for Liphatech, Inc. and for Kamprath Balansa was screened at several locations in a Seed Co., which imports balansa seed). range of soil types and climatic zones varying PARADANA is the cultivar that has been tested in from the Gulf Coast to northern Tennessee, and the U.S. It was released in 1985 by the South from Georgia to western Arkansas.Since the initial

158 MANAGING COVER CROPS PROFITABLY screening, a number of farmers have been evalu- They are easily incorporated into the soil. ating balansa in trials covering an even wider geo- Estimated amount of N fixed may range from 50- graphic area. 200 lb/acre, but bell bean is regarded as a low For further information, contact: nitrogen fixer in southern California. In six weeks Seth Dabney of growth,bell bean may fix up to 100 lb/acre and USDA-ARS National Sedimentation Lab. a total of up to 150 lb/acre on fertile soils. P.O. Box 1157 Seed 1 to 3 inches deep at 80-200 lb./A. Faba Oxford, MS 38655-2900 bean can grow on a wide range of soils, from (662) 232-2975; [email protected] loams to clays, and under a variety of drainage conditions.It does not tolerate saturated soils,and Bell bean (Vicia faba) extended drought, especially at flowering, Other common names: fava bean, faba bean, reduces seed production drastically. small-seeded horse bean. Bell beans are not drought tolerant. They are Type: Winter annual or spring annual legume. easier to control than other vetches.Bell beans do Description: Stems coarse, upright; leaves com- not tolerate close mowing. pound, usually with six broad leaflets and no ten- —Chuck Ingels drils; dark purple extrafloral nectary on lower University of California Extension surface of stipule; flowers large, white, with dark 4145 Branch Center Rd. purple blotches;pods large,cylindrical,containing Sacramento, CA 95827-3898 six to eight seeds. (916) 875-6913; FAX: (916) 875-6233 Bell bean is a true vetch,but differs greatly from [email protected] other vetches with its strong, upright growth. It also has a relatively shallow, thick taproot, which Black oats may be useful for opening up heavy soils. Bell Black oats (Avena strigosa) is the No. 1 cover bean often is used in mixtures with vetches, peas crop on millions of acres of conservation-tilled and/or cereals. Because of its height and because soybeans in southern Brazil. In the temperate it does not tolerate close mowing, it often is omit- farming regions of southern South America, black ted from mixtures in frost-prone areas. It is best oats owes its popularity to a number of factors. It adapted to Hardiness Zones 8 and 9. is very resistant to rusts and produces large Bell bean is frequently infested by the pea-bean amounts of biomass, similar to rye. It has excep- aphid, which seldom affects its use as a cover tional allelopathic activity for weed control. It is crop. The aphid, which does not attack grapes, easy to kill mechanically and cycles nitrogen bet- and the presence of extrafloral nectaries, may ter than rye. attract beneficial insects into vineyards. However, Black oats breaks disease cycles for wheat and their effects on insect and mite management have soybeans and is resistant (some research claims not been tested. even suppressive) to root-knot nematodes. On Bell bean is more susceptible to frost damage top of this, it is also a good forage. It is not cold than other vetches. It is very similar in growth to tolerant. broad bean (also known as Windsor or horse One cultivar, IAPAR-61, a public release devel- bean), which has a much larger, flat seed. The oped by the Paraná State Agricultural Research smaller seed size of bell bean makes it more eco- Service, has been investigated by USDA-ARS and nomical to sow. was grown in 1997 in Alabama and Georgia for Bell beans grow quickly throughout the winter commercial seed production. Its use likely will be in California, add N—although less than other restricted to the lower southern Coastal Plain vetches—and provide a tall structure to support (Zones 8b, 9 and 10). Seed should be available twining vetches and peas. Bell beans do not commercially in limited amounts in 1998. spread like vetches and they have no hard seed. —D.W.Reeves (see p. 161)

UP-AND-COMING COVER CROPS 159 Foxtail (German) millet Some vegetable growers in eastern states such Foxtail millet (Setaria italica) has a variety of as Maryland have planted foxtail millet after common names. Most literature refers to it as fox- spring vegetable harvest as a cover crop. Control tail millet due to its similarity to other members of methods later in the summer have included spray- the Setaria genus (several species of weedy fox- ing, mowing and rolling the crop flat (the rolling tails). Other common names include German mil- seems to provide a high percentage of control let, Hungarian millet and Italian millet. Compared without need for further action). to the weedy species of foxtail, this millet has a Disadvantages of foxtail millet are that it cannot much larger seed head, larger golden-colored be used after fall-harvested crops (too little vigor seed, bigger plants and a higher seed yield. This when planted in the cool fall months) and that it plant was used for centuries in China as an impor- could be a host to some pests of other cereal grain tant food grain. The crop has been grown as a crops—as is true of any grass cover crop. Foxtail food grain, forage and occasionally for birdseed millet is not likely to be a weed, since it does not production. The main use in the U.S. has been for have hard seed; any foxtail millet plants that vol- forage production, primarily in the Great Plains. unteer the next season can be easily controlled Foxtail millet is a warm season crop, and will similar to volunteer oats. not overwinter.Its best use as a cover crop would Some seed dealers sell foxtail millet under a be following spring-harvested vegetables in areas generic name, often as German millet (be sure otherwise left fallow for a summer,or in southern you are getting foxtail millet, and not some other regions as a cover crop planted in mid-summer. species such as proso millet or pearl millet). Although foxtail millet is a relatively short season University cultivars include RED SIBERIAN,GOLDEN crop (90 to 100 days in the lower Midwest), it GERMAN,WHITE WONDER,SNO-FOX and MANTA. Seed must be planted in the first half of the summer to dealers most likely to carry foxtail millet are those maximize biomass production. If planted late, located in the Great Plains region, particularly in such as mid-July through August,the plants will be Nebraska. much shorter in stature and less vigorous. —Robert L. Myers, Jefferson Institute The competitive advantage of foxtail millet lies 601 West Nifong Boulevard, Suite 1D, in its drought tolerance, relatively quick growth Columbia, MO 65203 and its status as a warm season annual that can be (573) 449-3518; [email protected] drilled in narrow rows.The crop is relatively easy to establish, like oats or wheat, and establishes Lupin best when drilled rather than broadcast.With ade- White lupin (Lupinus albus) and blue or narrow- quate rainfall, the crop will reach 3 to 4 feet tall leaf lupin (Lupinus angustifolius) are cool-season within about 50 to 60 days, but will be shorter annual legumes that provide plenty of N and can under limited moisture conditions or when plant- be grown widely in the U.S.and southern Canada. ed late. Foxtail millet fits a mid-summer niche not As a fall and winter cover crop in the southeast- filled by cool season grains such as wheat, oats ern U.S., white lupin is the most cold-tolerant. and rye. It provides more biomass in a short peri- Some cultivars overwinter as far north as the od than many warm season grasses, though per- Tennessee Valley (287). Spring cultivars can be haps not as much as sorghum or pearl millet. seeded in early April in the northern U.S. and Compared to those two crops however, foxtail southern Canada and plowed down around mid- millet may provide better erosion control because June when they’re in the early-bloom to early-pod it can be drilled in narrow rows. stage and at peak biomass. Foxtail millet is somewhat easier to establish For use as a cover crop, drill lupins no deeper than pearl millet, and although both are more than 1 inch at rates varying from 70 lb./A (for drought tolerant than corn, pearl millet would be small-seeded blue varieties) to 120 lb./A (for larg- favored on sandy soils. er-seeded white varieties). At $30 to $40 per acre,

160 MANAGING COVER CROPS PROFITABLY the seed is relatively expensive. Be sure to inocu- Sunn hemp late lupin seed with compatible rhizobia. A tropical legume that grows rapidly, sunn hemp Lupins have aggressive taproots, especially the (Crotalaria juncea) can produce more than narrow-leaf cultivars, and they can fix up to 350 5,000 lb.dry matter/A and 120 lb.N/A in just nine lb. N/A. Under normal growth conditions and to 12 weeks. It can fill a narrow niche between when killed in early spring, they typically contain harvest of a summer crop and planting of a fall 100 to 150 lb. N/A in their biomass.You can kill cash or cover crop. Sunn hemp sown by lupins easily either mechanically or with herbi- September 1 following a corn crop in Alabama,for cides.Their hollow stems crush or break readily, example, can produce an average of 115 lb. N/A making it easy to plant cash crops using conser- by December 1. vation tillage equipment. Sunn hemp is not winter hardy and a hard Lupin species were named after their original freeze easily kills it. Sow sunn hemp a minimum flower colors, but both species now have cultivars of nine weeks before the average date of the first that may have white,blue or magenta/purple flow- fall freeze. Seed at 40 to 50 lb./A, with a cowpea- ers.Blue lupin is adapted to the lower Coastal Plain type inoculant. and is more readily identified by its narrow leaflets Sunn hemp seed is expensive, about $2.25/lb., (about 0.5-inch wide) rather than flower color. so the cost may be prohibitive for large-scale Only two lupin cultivars are readily available on plantings. Seed can be produced only in tropical a commercial scale:TIFWHITE-78,a white lupin,and areas, such as Hawaii, and currently is imported TIFBLUE-78, a narrow-leaf lupin, both released by only by specialty seed companies. USDA’s Agricultural Research Service in the A management caution: Many Crotalaria 1980s. These two varieties, and other modern species contain alkaloids that are poisonous to varieties, are “sweet” types as opposed to “bitter” livestock. However, the sunn hemp variety TROPIC types that were widely grown in the South prior SUN, developed jointly by the University of Hawaii to 1950. Sweet varieties have a low concentration and USDA-NRCS, has a very low level of alkaloid of naturally occurring alkaloids.High alkaloid con- and is suitable for use as a forage. tent in the plants makes lupin seed and forage Research suggests that sunn hemp is resistant unpalatable for livestock. and/or suppressive to root-knot (Meloidogyne Recent research suggests that alkaloids play a spp.) and reniform (Rotylenchulus reniformis) major role in resistance to disease and pests nematodes. (including insects and nematodes). High-alkaloid —D.Wayne Reeves (see this page) lupins are therefore being selected and bred for use as cover crops rather than as animal feed. Teff Anecdotal evidence suggests that sweet lupin Teff (Eragrostis tef), or tef, is a grain grown pri- cover crops can act as a trap crop for thrips marily in Ethiopia, where it survives under harsh (Frankliniella spp.) in cotton plantings. conditions in poor soils. Teff has been researched Lupins are susceptible to some fungal and viral very little outside of east Africa, but has received diseases and should not be grown in the same occasional attention by U.S. researchers. Most field in successive years. It is best to rotate lupin small test plots have focused on teff as a cereal cover crops with a small grain cover crop. grain crop,but it also has potential as a forage,and For information about lupins and seed sources, is reportedly used some for grazing in South contact: America and Australia. D.Wayne Reeves, Research Agronomist, Limited studies point to teff’s ability to grow on USDA-ARS National Soil Dynamics Laboratory, poor soils. Although it is best to drill it, teff also 411 S. Donahue St., P.O. Box 3439 can be established by broadcast seeding because Auburn, AL 36832-5806 the seed is less than 1 mm in size.This allows the (334) 844-4666; FAX: (334) 887-8597 seed to fall into cracks and crevices of a prepared [email protected] 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 ic lines of teff available to researchers,but there is make it difficult to broadcast uniformly on a no commercial source of seed in the U.S. One windy day, and makes the seed hard to handle in farmer in the Pacific Northwest grows teff for many conventional planters. If broadcast, the Ethiopian restaurants and other buyers, but does seedbed probably should be tilled first—no infor- not routinely distribute seed. This would be a mation is available about broadcasting it under good crop for a plant breeder to breed and release no-till conditions. a variety for commercial distribution.Teff poten- Teff grows relatively quickly, and, although tially could be used for temporary ground cover short (18 to 24 in. tall), can establish a relatively during construction, when soil is left bare for a good ground cover. The leaf blades are narrow, period of months,but where a winter cover is not but the crop tends to establish a high number of needed.Teff does not produce quite the biomass plants per unit area.Teff is a warm season annual of some of the taller warm season grasses, but that is probably best planted in June in most because it can be broadcast, it may confer some states, which limits the conditions under which it advantages. Teff has not become a volunteer or would be cover cropped. It might possible to weed problem following several years of test plant it later, but this has not been tested. plots in Missouri. Its potential for serving as an The biggest limitation of teff as a cover crop is alternative pest host is unknown. the lack of a seed source.The USDA-ARS National —Robert L. Myers (see p. 160) Plant Germplasm System maintains several genet-

APPENDIX C RECOMMENDED RESOURCES

This list is for information purposes only. Inclusion does not Barnes, Robert F., et al. 1995. Forages:The Science imply endorsement, nor is criticism implied of similar of Grassland Agriculture. 5th Edition. 2 vol. Iowa resources not mentioned. State Univ.Press,Ames, Iowa. Abdul-Baki,Aref and John R.Teasdale. 1997. Sustainable Production of Fresh-Market Clark,Andrew J. et al. 1994. Seeding rate and kill Tomatoes and Other Summer Vegetables with date effects on hairy vetch-cereal rye cover crop Organic Mulches. Farmers’ Bulletin No. 2279, mixtures for corn production.Agron. J. 86: USDA-ARS, Beltsville, Md. 23 pp. 1065-1070. http://www.ars.usda.gov/is/np/tomatoes.html Cramer, Craig, George DeVault, Mike Brusko, Appropriate Technology Transfer for Rural Areas Fred Zahradnik and Lesa Ayers (eds.). 1985. The (ATTRA). 1998. Cover Crops and Green Farmer’s Fertilizer Handbook: How to make Manures: Benefits, Uses and Literature your own NPK recommendations…and make Resources.ATTRA. Fayetteville,Ark. them pay. Regenerative Agriculture Association, Emmaus, Pa. 176 pp. Bailey,R. G., P.E.Avers,T.King and W.H. McNab. 1994. Ecoregions and subregions of the United Dabney,S. M. 1995. Cover crops in reduced States (map).Washington, DC: USDA Forest tillage systems. pp. 126-127. Proc. Beltwide Service. 1:7,500,000.With supplementary table Cotton Conferences. 5 Jan 1995. National Cotton of map unit descriptions, compiled and edited Council, Memphis,Tenn. by W.H. McNab and R. G. Bailey. http://www.fs.fed.us/land/ecosysmgmt/pages/ ecoreg1_home.html

162 MANAGING COVER CROPS PROFITABLY Dyer, David A. 1998. Conservation Legume Macey,Anne. 1992. Organic Field Crop Varieties in the United States. USDA Handbook. Handbook. Canadian Organic Growers Inc., Plant Materials Center, P.O. Box 68, Lockeford, Ottawa, Ont. 192 pp. Practical handbook cover- Calif. 95237, (209) 727-5319. ing principles of organic farming, how to design crop rotations and species-specific chapters on Duke, James A. 1981. Handbook of Legumes of 11 cash and cover crops. World Economic Importance. Plenum Press, N.Y. 343 pp. Compendium of botanical, cultural and Matheson, Nancy,Barbara Rushmore, James R. management information. Excellent line Sims, Michael Spengler and E.L. Michalson. 1991. drawings. Cereal-Legume Cropping Systems: Nine farm case studies in the dryland northern plains, Duval, Jean. 1997. Cover Cropping in Potato Canadian prairies and intermountain Production. Ecological Agriculture Projects. Northwest.Alternative Energy Resources Publication No. 72.An eight-page bulletin with Organization (AERO), Helena, Mont. 75 pp.An concise descriptions of how to use legume, excellent description of these innovative systems cereal and brassica cover crops; excellent chart with clear diagrams and great management detail for planning rotations with benefit analysis of of how crops are selected. various covers. MacRae, R.J. and G.R. Mehuys. 1985.The effect of Hanson, James C. et al. 1993. Profitability of green manuring on the physical properties of no-tillage corn following a hairy vetch cover temperate-area soils. Adv. Soil Sci. 3:71-94. crop. J. Prod.Ag. 6:432-437. McVay,K.A. et al. 1989.Winter legume effects on Hanson, James C. et al. 1997. Organic versus soil properties and nitrogen fertilizer require- conventional grain production in the mid- ments. Soil Sci. Soc. of Amer.J. 53:1856-1862. Atlantic: an economic and farming system overview. Amer.J.Alt. Ag. 12:2-9. Michigan State University.1996. Cover Crops Symposium Proceedings. Michigan State Hargrove,W.L.(ed.). 1991. Cover Crops for Clean University,W.K.Kellogg Biological Station, Battle Water. Proc. Int’l Conf.April 9-11, 1991.West Creek, Mich. 20 pp. Tennessee Experiment Station, Jackson,Tenn. Soil and Water Conservation Society.Ankeny,Iowa. Miller, P.R.et al. 1989. Cover Crops for California Agriculture. University of California, Div.Of Ag. Hofstetter, Bob. 1988. The New Farm’s cover and Natural Resources Publication 21471, 24 pp. crop guide: 53 legumes, grasses and legume-grass Oakland, Calif. mixes you can use to save soil and money. The New Farm 10:17-22, 27-31. National Assn. of Wheat Growers Foundation. 1995. Best Management Practices for Wheat: Ingels, Chuck A.et al. 1994. Selecting the right cover A Guide to Profitable and Environmentally crop gives multiple benefits. Calif.Ag. 48:43-48. Sound Production. National Assn. of Wheat Growers Foundation.Washington, DC. Ingels, C.A., R.L. Bugg, G.T.McGourty,and L.P. Christensen. 1998. Cover Cropping in Vineyards: Oregon State University.1998. Using Cover A Grower’s Handbook. University of California, Crops in Oregon. Publication #EM-8704. Div.of Agriculture and Natural Resources. In Available for $5.50 from Publication Orders, Press. Chapters on cover crop species, soil/water Extension and Station Communications, management, pest management, 12 growers. Oregon State University,422 Kerr Administration, Charts of seeding rates, seed costs. Corvallis, OR 97331.

RECOMMENDED RESOURCES 163 Reeves, D.W.1994. Cover crops and rotations. pp. Sustainable Agriculture Network. Beltsville, Md. 125-172. In J.L. Hatfield and B.A. Stewart (eds.). Shows how today’s implements and techniques Crops Residue Management. 1994. Lewis can control weeds while reducing—or eliminat- Publishers,Ann Arbor, Mich. ing—herbicides. Farmer accounts include how cover crops and tillage tools are used in tandem Sainju, Upendra M. and Bharat P.Singh. 1997. to control weeds. Winter cover crops for sustainable agricultural systems: Influence on soil properties, water Teasdale, John R. 1996. Contribution of cover quality and crop yields. Hort Sci. 32:21-28. crops to weed management in sustainable Comprehensive overview of cover crop effects agriculture systems. J. Prod.Ag. 9:475-479. on N, soil organic C and N properties; chart on N contributions, water nitrate movement, University of California Sustainable Agriculture research needs. Research and Education Program. 1997. Cover Crops: Resources for Education and Extension. Sarrantonio, Marianne. 1994. Northeast Cover David Chaney and Ann D. Mayse, compilers. Crop Handbook. Soil Health Series. Rodale .Three-ring binder of Institute, Kutztown, Pa. 118 pp. educational resources including Internet, print materials, cover crop profiles, videos and slide Sarrantonio, M. 1991. Methodologies for sets, and a list of experts. screening soil-improving legumes. Rodale Institute. Kutztown, Pa. University of Wisconsin et al. 1990. Alternative Field Crops Manual. Univ.of Wisconsin- Shirley,Christopher and The New Farm staff. Extension and Univ.of Minnesota, Madison,Wis. 1993. What Really Happens When You Cut and St. Paul, Minn.Three-ring binder with Chemicals? Rodale Institute, Kutztown, Pa. Lots detailed descriptions of agronomic use for 35 of farmer profiles and details on usage of covers. crops and short narratives on 13 more crops. Tabbed, referenced. Smith, Miranda et al. 1994. The Real Dirt: Farmers Tell About Organic and Low-Input Wagger, Michael G. 1989.Winter annual cover Practices in the Northeast. Northeast Organic crops. pp. 59-61. In M.C. Cook and W.M. Lewis Farming Association and Northeast Region SARE, (Eds.). Conservation Tillage for Crop Production. Burlington,Vt. 264 pp. Publication No.AG-407.Agricultural Extension Service, North Carolina State University.Crimson, Stute, Jim. 1996. Legume Cover Crops in hairy vetch, cahaba vetch, field peas mentioned Wisconsin. Wisconsin Department of Agriculture, in this brief overview of planting and managing Sustainable Agriculture Program. Madison,Wis. cover crops. 27pp. Zalom, Frank G. 1995.A cover crop system for Stute, J.K. and J.L. Posner. 1995. Legume cover vineyard pest, weed and nutrition management. crops as a nitrogen source for corn in an #LW91-26.Western Regions SARE. Utah State oat-corn rotation. J. Prod.Ag. 8:385-390. Univ.Logan, Utah. Describes management of winter annuallegume/grass cover crops to control Sustainable Agriculture Network. 1997. leafhoppers, spider mites and weeds. Steel in the Field:A Farmer’s Guide to Weed Management Tools. Greg Bowman, ed.

164 MANAGING COVER CROPS PROFITABLY 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 mation center located at the University of http://www.sare.org Arkansas, has a website that features many of Browse or search for cover crop information: the publications and resource lists developed by The first edition of Managing Cover Crops program specialists in response to inquiries from Profitably, the database of SARE projects, and farmers since 1987. Call 1-800-346-9140 the archives of the sustainable agriculture listserv,sanet-mg. Ohio State University. 1995. The Value of Legumes for Plowdown Nitrogen. Managing Cover Crops Profitably http://ohioline.ag.ohio-state.edu/ USDA Sustainable Agriculture Network agf-fact/0111.html http://www.sare.org/htdocs/pubs/mccp/ This on-line version of the predecessor of this HELPFUL VIDEOS publication includes some covers not mentioned No-Till Vegetables—A Sustainable Way to here, plus guides to proven covers by region, Increase Profits, Save Soil and Reduce summaries of more than 30 cover crops and Pesticides mixes, and more.The information was compiled This 38-minute video covers the basics of sus- in 1991, but most of it is still useful. tainable no-till vegetable production including no-till transplanting into cover crops, pioneered Cover Crop Resource Page by Pennsylvania grower Steve Groff. Send $24.95 Sustainable Agriculture Research and Education ($26.95 for overseas orders) check or money Program (SAREP) order to: Cedar Meadow Farm, 679 Hilldale Road, University of California Holtwood Pa. 17532. For more info, email: http://www.sarep.ucdavis.edu/ccrop [email protected] or phone (717) 284-5152. An extensive site (not just for California farmers) that includes a searchable database of more than Using Cover Crops in Conservation 5,000 items, 400 online images and detailed Production Systems information on 32 cover crop species. Many An 11-minute video from the USDA-ARS National valuable gleanings from the scientific literature Sedimentation Lab in Oxford, MS, this program compiled in useful, readable form. can be obtained for $10 (postpaid) from: Shepherd Productions, 5004 Sequoia Rd, Cover Crops Menu Memphis,TN 38117-2016, (901) 272-0350 Sustainable Farming Connection http://sunsite.unc.edu/farming-connection/ Controlled Rotational Cover Cropping in covercro/home.htm the Bio-Extensive Market Garden Includes farmer features and links to other cover This 52-minute video ($10) explains how crop sites. intensive cover cropping serves as the base for carefully planned rotations of many crops in the ATTRA Nordell’s whole-farm vegetable system. Booklet http://www.attra.org ($10) also available (postpaid) from: Eric and Appropriate Technology Transfer for Rural Areas Anne Nordell, Beech Grove Farm, 3410 Route (ATTRA), a nation-wide sustainable farming infor- 184,Trout Run, Pa. 17771.

RECOMMENDED RESOURCES 165 APPENDIX D SEED SUPPLIERS

This list is for information purposes only. Inclusion does not Ampac Seed Co. imply endorsement, nor is criticism implied of firms not P.O. Box 318 mentioned. Tangent, OR 97389 Adams-Briscoe Seed Co. Inc. 800-547-3230 P.O. Box 19 fax 541-928-2430 325 E. Second St. [email protected] Jackson, GA 30233-0019 http://ampacseed.com 770-775-7826 forage grasses, legumes fax 770-775-7122 [email protected] Barenbrug http://www.abseed.com 33477 Highway 99 East forage/grain legumes, grains, summer annuals, Tangent, OR 97389 wildlife 541-926-5801 800-547-4101 Alabama Farmers Co-op fax 541-926-9435 P.O. Box 2227 forage legumes, grasses Decatur,AL 35609 256-353-6843 Birkett Mills fax 256-350-1770 P.O. Box 440 small grains, forage/grain legumes, summer Penn Yan, NY 14527 annuals (120 retail outlets) 315-536-3311 fax 315-536-6740 Albert Lea Seedhouse Inc. buckwheat P.O. Box 127 Albert Lea, MN 56007 Brett-Young Seeds Ltd. 800-352-5247 Box 99, St. Norbert Postal Station [email protected] Winnipeg, MB, Canada R3V 1L5 http://www.alseed.com 204-261-7932 grains, forage/grain legumes, grasses 800-665-5015 (Canada) fax 204-275-7333 Albright Seed Company [email protected] 487 Dawson Drive, Bay 5S forage legumes Camarillo, CA 93012 805-484-0551 Budd Seed 800-423-8112 191 Budd Blvd. fax 805-987-9021 Winston-Salem, NC 27114-5087 [email protected] 800-543-7333 http://www.albrightseed.com 336-760-9060 legumes, grasses and grains adapted to fax 336-765-3168 California bioregions grasses, red clover, subclover

166 MANAGING COVER CROPS PROFITABLY Cal/West Seeds Fedco Seeds Box 1428 P.O. Box 520 Woodland, CA 95776-1428 Waterville, ME 04903 800-327-3337 207-873-7333 800-824-8585 fax (same) fax 530-666-5317 grains, forage/grain legumes, brassicas whl: legumes, forages, clovers, Sudangrasses, vetches Fizzle Flat Farms—Marvin Manges 18773 E. 1600 Ave. Corland Seeds Yale, IL 62481 P.O. Box 336 618-793-2060 Guelph, ON N1H 6K5 fax (same) 519-763-2059 buckwheat, hairy vetch, rye (some certified 800-265-4321 organic) fax 519-763-5192 legumes, forages Frazier Seed Co. 309 W.Main St. DEKALB Genetics Corporation Anthony,KS 67003 3100 Sycamore Road 316-842-5106 DeKalb, IL 60115-9600 grains, cowpeas, winter peas 800-833-5252 [email protected] Harmony Farm Supply & Nursery http://www.dekalb.com P.O. Box 460 whl: sorghum-Sudangrass hybrids, forages Graton, CA 95444 707-823-9125 Discount Seed Inc. fax 707-823-1734 P.O. Box 84 forage/grain legumes 2411 9th Ave SW Watertown, SD 57201 Hobbs and Hopkins Ltd. 605-886-5888 1712 SE Ankeny Street fax 605-886-3623 Portland, OR 97214 grains, forage/grain legumes, forage grasses 503-239-7518 fax 503-230-0391 Ernst Conservation Seeds [email protected] 9006 Mercer Pike grasses RD 5 Box 806 Meadville, PA 16335 Hytest Seeds 814-336-2404 454 Railroad Ave. fax 814-336-5191 P.O. Box 3147 [email protected] Shiremanstown, PA 17011 http://www.ernstseed.com 717-737-4529 forage legumes, native species, wildlife 800-442-7391 fax 717-737-7168 grains, forage legumes, summer annuals

SEED SUPPLIERS 167 Johnny’s Selected Seeds Missouri Southern Seeds Foss Hill Road P.O. Box 699 Albion, ME 04910 Rolla, MO 65402 207-437-9294 573-364-1336 fax 207-437-2165 800-844-1336 [email protected] fax 573-364-5963 http://www.johnnyseeds.com wholesale (w/retail outlets): grains, forage grains, forage/grain legumes, rapeseed legumes, grasses, summer annuals (some untreated) North Country Organics Kamprath Seed Co. P.O. Box 372 205 Stockton St. 203 Depot St. Mateca, CA 95337 Bradford,VT 05033 209-823-6242 802-222-4277 800-325-4621 fax 802-222-9661 fax 209-823-2582 forage legumes, summer annuals many medics, subclovers, clovers, grasses, other legumes Olds Seed Solutions 2901 Packers Avenue Kaufman Seeds Madison,WI 53704 P.O. Box 398 608-249-9291 Ashdown,AR 71822 800-356-7333 870-898-3328 fax 608-249-0695 800-892-1082 forage legumes, brassicas, summer annuals, wholesale (50-lb. min.): grains, forage/grain grasses legumes, grasses, summer annuals Peaceful Valley Farm Supply Lohse Mill P.O. Box 2209 7752 County Road 29 Grass Valley,CA 95945 Glenn, CA 95943 916-272-4769 530-934-2157 fax 530-272-4794 fax 530-934-9106 http://www.groworganic.com grains, forage/dryland legumes grains, grasses, forage/grain legumes, brassicas, sunn hemp McDonald Ag Corp. P.O. Box 828 Pennington Seeds McMinville, OR 97128 P.O. Box 290 503-472-5158 Madison, GA 30650 [email protected] 800-285-7333 crimson and red clover by cultivar [email protected] http://www.penningtonseed.com Minnesota Seed Solutions grains, grasses, forage legumes 7800 State Highway 101 Shakopee, MN 55379 612-445-2606 wholesale (50-lb. min.): forgage/grain legumes, grains, grasses

168 MANAGING COVER CROPS PROFITABLY Pick Seed Canada Sweeney Seed Company P.O. Box 304 110 South Washington St. 1 Greenfield Rd Mount Pleasant, MI 48858 Lindsey,ON K9V 4S3 517-773-5391 905-623-2660 800-344-2482 fax 705-878-9249 fax 517-773-1216 clovers, grasses forage legumes, peas, summer annuals, rape

P.L. Rohrer & Bro. Co. Tennessee Farmers Co-op P.O. Box 250 200 Waldron Road Smoketown, PA 17576 P.O. Box 3003 717-299-2571 LaVergne,TN 37086 fax 717-299-5347 615-793-8506 grains, grasses, forage legumes, brassicas grains, forage legumes, peas

Rupp Seeds, Inc. Timeless Seeds 17919 Co. Rd. B P.O. Box 881 Wauseon, OH 43567 Conrad, MT 59425 419-337-1841 406-278-5770 fax 419-337-5491 fax 406-278-5720 grains, grasses, forage legumes [email protected] dryland forage/grain legumes Seedway Inc. P.O. Box 250 The Wax Co., Inc. Hall, NY 14463 204 Front St. N 800-836-3710 Amory,MS 38821 fax 716-526-6832 662-256-3511 Grains, forage/grain legumes, grasses, brassicas, annual ryegrass summer annuals Welter Seed and Honey Co. Seimer/Mangelsdorf Seed Co. 17724 Hwy.136 96300 Collinsville Rd. Onslow,IA 52321-7549 East St. Louis, IL 62201 319-485-2762 800-467-7333 800-728-8450 fax 618-271-4199 800-470-3325 grains, cowpeas, summer annuals, wildlife grains, grasses, forage/grain legumes, summer annuals Southern States Cooperative 2600 Durham St. Wolf River Valley Seeds Richmond,VA 23220 N2976 County M 800-868-6273 White Lake,WI 54491 wholesale (retail outlets in 6 states): grains, 715-882-3100 forage legumes, cowpeas, summer annuals 800-359-2480 [email protected] grains, forage/grain legumes

SEED SUPPLIERS 169 INOCULANT SUPPLIERS Urbana Laboratories LiphaTech Inc. (Nitragin inoculants) P.O. Box 1393 3101 W.Custer Ave. 310 S.Third St. Milwaukee,WI 53209 St. Joseph, MO 64502 414-462-7600 816-233-3446 800-558-1003 800-892-2013 fax 414-462-7186 fax 816-233-8295 [email protected] [email protected] http://www.liphatech.com inoculants for major/minor inoculants for major/minor temperate, temperate climate legumes tropical climate legumes

APPENDIX E FARMING ORGANIZATIONS WITH COVER CROP EXPERTISE

This list is for information purposes only. Inclusion does not Chesapeake Wildlife Heritage imply endorsement, nor is criticism implied of organizations P.O. Box 1745 not mentioned. Easton, MD 21601 Note: CC denotes cover crop(s) or cover cropping. 410-822-5100 fax 410-822-4016 ORGANIZATIONS—NORTHEAST [email protected] The Accokeek Foundation http://www.cheswildlife.org 3400 Bryan Point Road CC in organic & sustainable farming systems; Accokeek, MD 20607 consulting & implementation in Mid-shore Md 301-283-2113 area as they relate to farming & wildlife fax 301-283-2049 [email protected] Pennsylvania Association for Sustainable http://www.accokeek.org Agriculture (PASA) land stewardship and ecological agriculture P.O. Box 419 using CC 114 W.Main St Millheim, PA 16854 Center for Sustainable Agriculture 814-349-9856 590 Main St. fax 814-349-9840 Burlington,VT 05405 [email protected] 802-656-5459 http://www.pasafarming.org fax 802-656-8874 on farm CC demonstrations [email protected] http://www.uvm.edu/~susagctr

170 MANAGING COVER CROPS PROFITABLY SARE Northeast Region Office Leopold Center for Sustainable Agriculture University of Vermont Iowa State University 10 Hills Building 209 Curtiss Hall Burlington,VT 05405-0082 Ames, IA 50011-1050 802-656-0471 515-294-3711 fax 802-656-4656 fax 515-294-9696 [email protected] [email protected] http://www.uvm.edu/~nesare/index.html http://www.ag.iastate.edu/centers/leopold support research, demos, education projects in Iowa on CC systems ORGANIZATIONS—NORTH CENTRAL Center for Integrated Agricultural Systems SARE North Central Region Office (CIAS) University of Nebraska-Lincoln University of Wisconsin-Madison 13-A Activities Bldg. 1450 Linden Drive P.O. Box 830840 Madison,WI 53706-1562 Lincoln, NE 68583 608-262-5200 402-472-7081 fax 608-265-3020 fax 402-0280 [email protected] [email protected] http://www.wisc.edu/cias/ http://www.sare.org/ncrsare/ CC resource locator in Wisconsin/ Upper Midwest ORGANIZATIONS—SOUTH Appropriate Technology Transfer for Rural Conservation Technology Information Areas (ATTRA) Center (CTIC) P.O. Box 3657 1220 Potter Drive, Rm 170 Fayetteville,AR 72702 West Lafayette, IN 47906 1-800-346-9140 765-494-9555 http://www.attra.org/ fax 765-494-5969 ATTRA is a leading information source for [email protected] farmers and extension agents thinking about http://www.ctic.purdue.edu sustainable farming practices conservation tillage series fact sheets provider Educational Concerns for Hunger Land Stewardship Project Organization 2200 4th Street ECHO White Bear Lake, MN 55110 17430 Durrance Rd. 612-653-0618 North Ft. Myers, FL 33917 fax 612-653-0589 941-543-3246 [email protected] fax 941-543-5317 http://www.misa.umn.edu/~lsp/ [email protected] http://www.echonet.org/ provides technical information and seeds of tropical cover crops

ORGANIZATIONS 171 The Kerr Center for Sustainable Northern Plains Sustainable Agriculture Inc. Agriculture Society PO Box 588 9824 79th St S.E. Highway 271 South Fullerton, ND 58441-9725 Poteau, OK 74953 701-883-4304 918-647-9123 fax 701-883-4304 fax 918-647-8712 [email protected] http://www.kerrcenter.com/ http://www.npsas.org CC systems demonstrations & research CC systems for small grains

SARE Southern Region Office SARE Western Region Office University of Georgia Utah State University 1109 Experiment Street 4865 Old Main Hill Georgia Station Room 322 Griffin, GA 30223-1797 Logan, UT 84322 770-412-4787 435-797-2257 fax 770-412-4789 [email protected] [email protected] http://wsare.usu.edu/ http://www.griffin.peachnet.edu/sare/ Small Farm Center Texas Organic Growers Association University of California P.O. Box 15211 One Shields Avenue Austin,TX 78761 Davis, CA 95616 1-877-326-5175 530-752-8136 fax 512-842-1293 fax 530-752-7716 [email protected] [email protected] http://www.texasorganicgrowers.com/ http://www.sfc.ucdavis.edu/ TOGA is helping to make organic agriculture serves as a clearinghouse for questions from viable in Texas and offers a quarterly periodical. farmers, marketers, farm advisors, trade associations, government officials and agencies, and the ORGANIZATIONS—WEST academic community Center for Agroecology & Sustainable Food Systems University of California SAREP 1156 High Street One Shields Avenue Santa Cruz, CA 95064 Davis, CA 95616-8716 831-459-4367 530-752-7556 fax 831-459-2799 fax 530-754-8550 http://zzyx.ucsc.edu/casfs/ [email protected] facilitates the transfer of successful organic http://www.sarep.ucdavis.edu/ farming and technical advice

172 MANAGING COVER CROPS PROFITABLY APPENDIX F REGIONAL EXPERTS

These individuals are willing to briefly respond to specific Jim Crawford questions in their area of expertise, or to provide referral to New Morning Farm others in the sustainable agriculture field. Please respect their schedules and limited ability to respond. HCR 71, Box 168B Hustontown, PA 17229 Note: CC denotes cover crop(s) or cover cropping. 814-448-3904 fax 814-448-2333 NORTHEAST 25 years of CC in vegetable production systems Aref A.Abdul-Baki USDA/ARS Vegetable Lab Mark Davis BARC-West USDA/ARS Soil Microbial Systems Bldg. 010A Rm 213 BARC-West 10300 Baltimore Ave Bldg. 001, Rm 137 Beltsville, MD 20705 Beltsville, MD 20705-2350 301-504-5057 301-504-9068 x342 fax 301-504-5555 fax 301-504-8370 [email protected] [email protected] CC systems for vegetables, soil permeation & fer- CC for organic cropping systems tility A. Morris Decker C.E. Beste 5102 Paducah Rd. 27664 Nanticoke Rd. College Park, MD 20740 Salisbury,MD 21801 301-441-2367 410-742-8780 Prof. Emeritus, University of Maryland. 40 years fax 410-742-1922 forage mgt., CC & agronomic cropping systems [email protected] research CC systems & no-till equipment for vegetables Steve Groff Andy Clark-SAN Coordinator Cedar Meadow Farm Sustainable Agriculture Network 679 Hilldale Rd. National Agricultural Library Holtwood, PA 17532 10301 Baltimore Ave Rm. 304 717-284-5152 Beltsville, MD 20705 fax 717-284-5967 301-504-6425 [email protected] fax 301-504-6409 http://www.cedarmeadowfarm.com [email protected] CC/no-till strategies for vegetable & http://www.sare.org agronomic crops technical information specialist for sustainable agriculture; legume/grass CC mixtures

REGIONAL EXPERTS 173 H.G. Haskell Jack Meisinger 4317 S. Creek Rd. USDA/ARS Chadds Ford, PA 19317 BARC-West tel/fax 610-388-0656 Bldg. 007 Rm 205 rye/vetch mix for green manure and erosion 10300 Baltimore Ave control Beltsville, MD 20705 301-504-5276 x431 Zane R. Helsel, Director of Extension [email protected] Rutgers Cooperative Extension nitrogen management in CC systems Rutgers,The State University of NJ 88 Lipman Dr. Anne and Eric Nordell New Brunswick, NJ 08901-8525 3410 Route 184 732-932-5000 x581 Trout Run, PA 17771 fax 732-932-6633 570-634-3197 [email protected] rotational CC for weed control http://www.rce.rutgers.edu CC for field crop systems Marianne Sarrantonio University of Maine Stephen Herbert 102 Deering Hall University of Massachusetts Orono, ME 04469 Dept. of Plant & Soil Sciences 207-581-2913 Bowditch Hall, Box 30910 fax 207-581-2999 Amherst, MA 01003 [email protected] 413-545-2250 legumes, soil health & nitrogen cycling fax 413-545-0260 [email protected] Eric Sideman CC culture, soil fertility,crop nutrition & nitrate Maine Organic Farmers & Gardeners Assoc. leaching P.O. Box 170 Common Ground County Fair Bob Hofstetter Unity,ME 04988 Indian Rock Produce 207-568-4142 530 California Road fax 207-568-4141 Quakertown, PA 18951 [email protected] 215-538-1328 http://www.mofga.org/ CC for inter-seeding and over-seeding in field & MOFGA offers information & technical bulletins vegetable crops on CC selection & growth

Dr. Amadou Makhtar Diop John Teasdale Information Coordinator USDA/ARS The Rodale Institute BARC-West 611 Siegfriedale Rd. Bldg. 001 Rm 323 Kutztown, PA 19530 10300 Baltimore Ave 610-683-1400 Beltsville, MD 20705 fax 610-683-8548 301-504-5504 [email protected] fax 301-504-6491 http://www.rodaleinstitute.org [email protected] 333 acre farm & demonstration garden w/ CC; CC mgt./mixtures & weed suppression contact info and publications provider

174 MANAGING COVER CROPS PROFITABLY David W. Wolfe Greg Endres Cornell University Carrington Research Extension Center 168 Plant Science Bldg. NDSU-CREC Ithaca, NY 14853 Box 219 607-255-7888 Carrington, ND 58421 fax 607-255-9998 701-652-2951 x108 [email protected] fax 701-652-2055 CC for improved soil quality in vegetable [email protected] cropping systems cropping systems & weed mgt. in the Dakotas

NORTH-CENTRAL Rick Exner Dan Anderson Practical Farmers of Iowa University of Illinois Agroecology/Sustainable ISU Extension Service Agriculture Program 2104 Agronomy Hall W-503 Turner Hall Ames, IA 50011 1102 S. Goodwin 515-294-5486 Urbana, IL 61801 fax 515-294-9985 217-333-1588 [email protected] fax 217-333-7370 http://www.pfi.iastate.edu [email protected] on farm CC research for the upper Midwest on-farm CC trials throughout Illinois Carmen M. Fernholz Rich Bennett State Chair of the SFA of MN RR 5 Rt. 2 Box 9A 7 740 P3 Madison, MN 56256 Napoleon, OH 43545 320-598-3010 419-748-8187 fax 320-598-7347 CC for soil quality & herbicide/pesticide reduc- [email protected] tion Robert N. Fogg John Cardina Fogg Organic Farms Ohio State University-OARDC 2665 Bellevue Rd. 215 Williams Hall Leslie, MI 49251 Wooster, OH 44691 517-589-5590 330-263-3644 fax 517-589-5596 [email protected] CC for soil improvement in a closed organic CC for sustainable weed control system

Stephan A. Ebelhar Dr. Mohammadreza Ghaffarzadeh Dixon Springs Agricultural Center Research Manager Route 1, Box 256 Agronomy Services Simpson, IL 62985 Pioneer Hi-Bred International 618-695-2790 6900 NW 62nd Ave. fax 618-695-2492 Johnston, Iowa 50131-0256 [email protected] [email protected] CC systems for no-till corn & soybeans sustainable cropping systems using berseem clover

REGIONAL EXPERTS 175 Walter Goldstein or Jim Stute Rob Myers Michael Fields Agricultural Institute Jefferson Institute W2493 County ES 601 West Nifong Blvd, Suite 1D East Troy,WI 53120 Columbia, MO 65203 262-642-3303 573-449-3518 fax 262-642-4028 fax 573-449-2398 [email protected] [email protected] CC for nutrient cycling & soil health in biody- CC systems and crop diversification namic & conventional systems Michael Rahe Richard R. Harwood Bureau of Land and Water Resources Michigan State University Illinois Dept. of Agriculture Crop & Soil Sciences Dept. P.O. Box 19281 260 Plant & Soil Sciences Bldg. Springfield, IL 62794-9281 East Lansing, MI 48824 217-782-6297 517-432-1611 fax 217-524-4882 fax 517-353-3834 [email protected] [email protected] CC information for referrals, research & projects CC systems & field crop agroecology David R. Swaim Frederick Kirschenman Swaim & Associates Rt 1 Box 73 Agronomic Consulting Winsor, ND 58424 1730 Camp Rotary Road 701-763-6287 Crawfordsville, IN 47933 fax 701-486-3580 765-362-4946 CC systems for cereal grains, soil quality fax 765-361-9096 & pest mgt. [email protected] CC with conservation tillage, soil fertility & crop Matt Liebman nutrition Iowa State University Department of Agronomy Richard Thompson 3218 Agronomy Hall Thompson On-Farm Research Ames, IA 50011 2035 190th St. [email protected] Boone, IA 50036-7423 green manures & CC for field and vegetable 515-432-1560 systems CC system in corn-soybean-corn-oats-hay rotation

Dale Mutch SOUTH W.K.Kellogg Biological Station Philip J. Bauer District IPM Agent USDA/ARS 3700 E. Gull Lake Dr. Cotton Production Research Center Hickory Corners, MI 49060-9505 2611 Lucas St. 616-671-2412 Florence, SC 29501-1241 fax 616-671-4485 843-669-5203 x7250 [email protected] fax 843-662-3110 http://www.msue.msu.edu/sycamore/cover.htm [email protected] general CC information provider CC systems for cotton production

176 MANAGING COVER CROPS PROFITABLY Bob Burdette Greg D. Hoyt Southern Seed Certification Assoc. MHCREC P.O. Box 2619 2016 Fanning Bridge Rd. Auburn,AL 36831 Fletcher, NC 28732 334-821-7400 or 334-844-4995 828-684-3562 specialty CC & seed development [email protected] CC for vegetables, tobacco & corn Nancy Creamer North Carolina State University Noah N. Ranells Horticultural Science Dept. North Carolina State University Box 7609 1114A Williams Hall Raleigh, NC 27695 Box 7620 919-515-9447 Raleigh, NC 27695-7620 fax 919-515-2505 919-515-7597 [email protected] fax 919-515-5885 CC systems for no-till vegetables & weed control [email protected] grass/legume CC for improved water quality Seth Dabney USDA/ARS D. Wayne Reeves National Sedimentation Lab USDA/ARS P.O. Box 1157 National Soil Dynamics Laboratory Oxford, MS 38655 411 S. Donahue St. 662-232-2975 Auburn,AL 36832-5806 fax 662-232-2915 [email protected] [email protected] 334-844-4666 legume reseeding & mechanical control of CC in fax 334-887-8597 the mid-South K.H. Quesenberry Phillip Davis University of Florida Route 1 Box 208 P.O. Box 110500 Old Fort, NC 28762 Gainesville, FL 32611 tel/fax 828-668-9800 352-392-1811 CC for corn, soybeans & tobacco fax 352-392-1840 [email protected] Mario DeLuca CC systems in Florida McDowell County Extension Service County Administration Bldg., Rm 226 Jac Varco Marion, NC 28752 Mississippi State University 828-652-7121 ext. 249 Plant & Soil Sciences Dept. Box 9555 fax 828-659-3484 Mississippi State, MS 39762 [email protected] 662-325-2737 http://mcdowell.ces.state.nc.us/staff/mdeluca/pe fax 662-325-8742 rsonalold.html [email protected] CC information for corn and soybean CC & fertilizer mgt. in no-till cotton production production mgt. systems

REGIONAL EXPERTS 177 Michael G. Wagger Ron Delaney North Carolina State University University of Wyoming Dept. of Soil Science Dept. of Plant Sciences P.O. Box 7619 P.O. Box 3354 Raleigh, NC 27695-7619 Laramie,WY 82071-3354 919-515-4269 307-766-3103 fax 919-515-2167 fax 307-766-5549 [email protected] [email protected] nutrient cycling in CC based production systems semi-arid annual legumes

WEST Richard Dick Miguel A. Altieri Oregon State University University of California at Berkeley Dept. of Crop & Soil Science 215 Mulford Hall Ag and Life Sciences, Bldg 3067 Berkeley,CA 94720-3112 Corvallis, OR 97331 510-642-9802 541-737-5718 fax 510-642-7428 fax 541-737-5725 [email protected] [email protected] http://nature.berkeley.edu/~agroeco3 nitrogen cycling & environmental applications of CC to enhance biological pest control in peren- CC systems nial systems Charlotte Eberlein Robert Bugg University of Idaho University of California at Davis Twin Falls Research and Ext. Center 159 DANR Building 317 Falls Avenue Davis, CA 95616 Twin Falls, ID 83303-1827 530-754-8549 208-736-3600 fax 530-754-8550 fax 208-397-4311 [email protected] [email protected] CC selection, growth & IPM CC for weed control in potatoes

David Chaney-SAREP Education Chuck Ingels Coordinator UC Cooperative Extension University of California 4145 Branch Center Rd. One Shields Avenue Sacramento, CA 95827-3898 Davis, CA 95616-8716 916-875-6913 [email protected] fax 916-875-6233 530-754-8551 [email protected] fax 530-754-8550 farm advisor-pomology,viticulture, & environmental horticulture

178 MANAGING COVER CROPS PROFITABLY Shiou Kuo Clara I. Nicholls Washington State University University of California Research & Extension Center Department of Environmental Science Policy 7612 Pioneer Way East and Management Puyallup,WA 98371 Division of Insect Ecology 253-445-4573 Berkeley,CA 94704 fax 253-445-4621 510-642-9802 [email protected] fax 510-642-7428 CC effects on soil, water quality and crop [email protected] productivity CC for biological control in vineyard systems

John M. Luna James R. Sims Oregon State University 21 Border Lane Dept. of Horticulture Bozeman, MT 59715 4143 Agricultural and Life Sciences Bldg. tel/fax 406-582-1576 Corvallis, OR 97331 dryland & alternate cropping systems 541-737-5430 fax 541-737-3479 Fred Thomas [email protected] CERUS Consulting CC for integrated vegetable production systems 766 E.Avenue, & agroecology #C Chico, CA 95926 Nancy Matheson 530-891-6958 3845 Hart Lane fax 530-891-5248 Helena, MT 59602 [email protected] 406-227-9161 CC systems specialist for all 406-227-0389 agricultural crops [email protected]

Dwain Meyer North Dakota State University Loftsgard Hall, Room 470E Extension Service Fargo, ND 58105 701-231-8154 [email protected] yellow blossom sweet clover specialist

REGIONAL EXPERTS 179 APPENDIX G CITATIONS BIBLIOGRAPHY

The publications cited in the text (in parentheses) are listed 10 Badaruddin, M. and D.W.Meyer. 1990. Green- here by reference number. manure legume effects on soil nitrogen, grain yield, and nitrogen nutrition of wheat. 1 Abdul-Baki,Aref A. and John R.Teasdale. 1993.A Crop Sci. 30:819-825. no-tillage tomato production system using hairy vetch and subterranean clover mulches. 11 Bagegni,Ali. M. et al. 1994. Herbicides with HortSci. 28:106-108. crop competition replace endophytic tall fescue (Festuca arundinacae). Weed Tech. 8:689-695. 2 Abdul-Baki,Aref and John R.Teasdale. 1997. Sustainable Production of Fresh-Market 12 Ball, Donald M. and Robert A.Burdett. 1977. Tomatoes and Other Summer Vegetables with Alabama Planting Guide for Forage Grasses. Organic Mulches. Farmers’ Bulletin No. 2279, Alabama Cooperative Extension Service, Chart USDA/ARS, Beltsville, Md. 23 pp. ANR 149.Auburn Univ.,Auburn,Ala.

3 Alger, Jess. 1997. Personal communication. 13 Ball, Donald M. and Robert A.Burdett. 1977. Stanford, Mont. Alabama Planting Guide for Forage Legumes. Alabama Cooperative Extension Service, Chart 4 American Forage and Grassland Council ANR 150.Auburn Univ.,Auburn,Ala. National Fact Sheet Series. Subterranean clover. http://forages.orst.edu/main.cfm?PageID=33 14 Barker, Kenneth R. 1996.Animal waste, winter cover crops and biological antagonists for 5 Anderson, Glenn. 1997. Personal sustained management of Columbia lance and communication. Hilmar, Calif. other nematodes on cotton. pp. 19-20. Southern Region 1996 Annual Report. Griffin, Ga. 6 Angers, D.A. 1992. Changes in soil aggregation and organic carbon under corn and alfalfa. Soil 15 Barnes, Robert F.et al. 1995. Forages:The Sci. Soc.Am. J. 56:1244-1249. Science of Grassland Agriculture. 5th Edition. Iowa State Univ.Press,Ames, Iowa. 7 Appropriate Technology Transfer for Rural Areas (ATTRA). 1991 Cover Crops and Green 16 Bauer, P.J. et al. 1993. Cotton yield and fiber Manures. ATTRA. Fayetteville,Ark. quality response to green manures and nitrogen. Agron. J. 85:1019-1023. 8 Arshad, M.A. and K.S. Gill. 1996. Crop production, weed growth and soil properties under 17 Bauer, P.J. 1997. Personal communication. three fallow and tillage systems. J. Sustain.Ag. USDA-ARS. Florence, S.C. 8:65-81. 18 Beale, P.et al. 1985. Balansa Clover—a New 9 Badaruddin, M. and D.W.Meyer. 1989.Water use Clover-Scorch-Tolerant Species. South Australia by legumes and its effects on soil water status. Dept. of Ag. Fact Sheet. Crop Sci. 29:1212-1216. 19 Beste, C. Edward. 1997. Personal communication. Univ.of Maryland-Eastern Shore, Salisbury,Md.

180 MANAGING COVER CROPS PROFITABLY 20 Bird, George. 1997. Personal communication. 32 Bruce, R.R, P.F.Hendrix and G.W.Langdale. Michigan State Univ.East Lansing, Mich. 1991. Role of cover crops in recovery and maintenance of soil productivity.pp.109-114. In W.L. 21 Bloodworth, L.H. and J.R. Johnson. 1995. Hargrove (ed.), Cover Crops for Clean Water.Soil Cover crops and tillage effects on cotton. J. Prod. and Water Conservation Society.Ankeny,Iowa. Ag. 8:107-112. 33 Bruce, R.R. et al. 1992. Soil surface 22 Bollich, P.K.1997. Personal communication. modification by biomass inputs affecting rainfall Louisiana State Univ..Crowley,La. infiltration. Soil Sci. Soc.Am. J. 56:1614-1620.

23 Boquet, D.J. and S.M. Dabney.1991. Reseeding, 34 Brunson, K.E. 1991.Winter cover crops in biomass, and nitrogen content of selected winter the integrated pest management of sustainable legumes in grain sorghum culture. Agron. J. cantaloupe production. M.S.Thesis. Univ.of 83:144-148. Georgia,Athens, Ga.

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189 Lanini,W.T.et al. 1989. Subclovers as living 198 MacGuidwin,A.E. and T.L.Layne. 1995. mulches for managing weeds in vegetables. Response of nematode communities to sudan- Calif.Agric. 43:25-27. grass and sorghum-sudangrass hybrids grown as green manure crops. J. Nematol. 27:609- 616. 190 Leach, S.S. 1993. Effects of moldboard plowing, chisel plowing and rotation crops on the 199 Maddox, Erol. 1997. Personal Rhizoctonia disease of white potato. American communication. Hebron, Md. Potato Journal 70:329-337. 200 Mackay.1981. Medics, general. Univ.of Calif. 191 LeCureux, James P.1996. Integrated system SAREP Cover Crops Resource Page. for sustainability of high-value field crops. Project http://www.sarep.ucdavis.edu/ccrop/ Report #LNC94-64. North Central Region SARE. Lincoln, Neb. 201 Mahler, R.L. 1989. Evaluation of the green manure potential of Austrian winter pea in 191.1 Leroux, G.D. et al. 1996. Effect of crop rota- northern Idaho. Agron. J. 81:258-264. tions in weed control, Bidens cernua and Erigeron canadensis populations, and carrot yields in organ- 202 Mahler, R.L. 1993. Evaluation of the nitrogen ic soils. Crop Protection 15:171-178. fertilizer value of plant materials to spring wheat production. Agron J. 85:305-309. 192 Lichtenberg, E., J.C. Hanson,A.M. Decker and A.J. Clark. 1994. Profitability of legume cover 203 Malik, N. and J.Waddington. 1988. Polish crops in the mid-Atlantic region. J. Soil Water rapeseed as a companion crop when Cons. 49:582-585. establishing sweetclover for dry matter production. Can. J. Plant. Sci. 68:1009-1015. 193 Linn, D.M. and J.W.Doran. 1984. Effect of water-filled pore space on carbon dioxide and 204 Marks and Townsend. 1973. Buckwheat. nitrous oxide production in tilled and nontilled Univ.of Calif. SAREP Cover Crops Resource Page. soil. Soil Sci. Soc.Am. J. 48:1267-1272. http://www.sarep.ucdavis.edu/ccrop/

194 LiphaTech. 1997. Personal communication. 205 Martin,Todd. 1997. Personal communication. Milwaukee,Wis. Michigan State Univ.W.K.Kellogg Biological Station, Hickory Corners, Mich.

BIBLIOGRAPHY 189 206 Marshall, H.G. and Y.Pomeranz. 1982. 216 Michigan State Univ.Extension. 1996. Cover Buckwheat: description, breeding, production Crops: MSU/KBS (factsheet packet).“Cover and utilization. pp. 157-210. In Advances in Crops General Information,”“Cover Crop Seeding Cereal Science and Technology (Y.Pomeranz, Methods and Equipment,”“Managing Cover ed.).Amer.Assn. of Cereal Chemists, Inc., Crops in Michigan,”“Red Clover,”“Annual St. Paul, Minn. Medics,”“Sources of Cover Crop Seed for Michigan.”MSU. East Lansing, Mich. http://www. 207 Matthews,Allen. 1997.Alternative rotation kbs.msu.edu/extension/Covercrops/home.htm system for vegetables. Project Report #FNE96- 146. Northeast Region SARE. Burlington,Vt. 217 Michigan State Univ..1996. Cover Crops Symposium Proceedings. Michigan State Univ., 208 Matthews,Allen. 1997. Personal W.K.Kellogg Biological Station, Battle Creek, communication. Scenery Hill, Pa. Mich.

209 McCraw,Dean et al. 1995. Use of Legumes 218 Miller, Michelle M. 7/21/97. Reduced input, in Pecan Orchards. Oklahoma Cooperative diversified systems. Press release via electronic Extension Service. Current Report CR-06250, 4 transmission from Univ.of Wisconsin Extension- pp. Stillwater, OK. Agronomy,Madison,Wis.

210 McGuire, C.F.et al. 1989. Nitrogen contribution 219 Miller, P.R.et al. 1989. Cover Crops for of annual legumes to the grain protein content of California Agriculture. University of California, ‘Clark’ barley (Hordeum disticum L.) production. SAREP.Div.of Agriculture and Natural Resources. Applied Ag. Res. 4:118-121. Davis, Calif. 24 pp.

211 McLeod. Medics, general. Univ.of Calif. 220 Miller, M.H. et al.1994. Leaching of nitrogen SAREP Cover Crops Resource Page. and phosphorus from the biomass of three cover http://www.sarep.ucdavis.edu/ccrop/ crops. J. Environ. Qual. 23:267-272.

212 McSorley,R. and R.N. Gallagher. 1994. Effect 221 Miller, 1989. Medics, general. Univ.of Calif. of tillage and crop residue management on SAREP Cover Crops Resource Page. nematode densities on corn. J. Nematol. http://www.sarep.ucdavis.edu/ccrop/ 26:669-674. 222 Millhollon, E.P.1994.Winter cover crops 213 Meisinger, J.J. et al.1991. Effects of cover improve cotton production and soil fertility in crops on groundwater quality.pp. 57-68. In Northwest Louisiana. La.Ag. 37:26-27. Cover Crops for Clean Water (W.L.Hargrove, ed.). Proc. Int’l Conf.April 9-11, 1991.West 223 Mishanec, John. 1996. Use of sorghum- Tennessee Experiment Station, Jackson,Tenn. Soil sudangrass for improved yield and quality of and Water Conservation Society.Ankeny,Iowa. vegetables produced on mineral and muck soils in New York: Part II—Sudan trials on 214 Meyer, Dwain. 1997. Personal communica- muck soils in Orange County. Research report. tion. North Dakota Extension Service. Fargo, N.D. Cornell Cooperative Extension. Ithaca, N.Y.

215 Meyer, D.W.and W.E.Norby.1994. Seeding 224 Mishanec, John. 1997. Personal rate, seeding-year harvest, and cultivar effects on communication. Ithaca, N.Y. sweetclover productivity. North Dakota Farm Res. 50:30-33. 225 Mississippi State Univ.website. http://ext.msstate.edu/pubs/

190 MANAGING COVER CROPS PROFITABLY 226 Mohler, Charles L. 1994.A living mulch 236 Murphy,A.H. et al. 1976. Medic, bur. Univ.of (white clover)/dead mulch (compost) weed Calif. SAREP Cover Crops Resource Page. control system for winter squash. Unpublished http://www.sarep.ucdavis.edu/ccrop/ research paper. Ecology and Systematics, Cornell Univ.,Ithaca, NY. 237 Murray,Glen A.1997. Personal communication. Univ.of Idaho. Moscow,Idaho. 227 Mojtahedi, H. et al. 1993. Suppression of Meloidogyne chitwoodi with sudangrass culti- 238 Mutch, D.R., Gary L. Zehr,Todd E. Martin and vars as green manure. J. Nematol. 25:303-311. Tim Duckert. 1996. Evaluation of low-input corn system. In Cover Crops Symposium Proceedings. 228 Moomaw,R.S. 1995. Selected cover crops Michigan State Univ.,W.K.Kellogg Biological established in early soybean growth stage. J. Soil Station. Battle Creek, Mich. and Water Cons. 50:82-86. 239 Mutch, D.R. et al. 1996. Evaluation of over- 229 Moore, Steve. 1997. Personal seeded cover crops at several corn growth stages communication. Center for Sustainable Living. on corn yield. In Cover Crops Symposium Wilson College. Chambersburg, Pa. Proceedings. Michigan State Univ.,W.K.Kellogg Biological Station, Battle Creek, Mich. 230 Moyer, Jeff. 1997. Personal communication. Rodale Institute Experimental Farm. 240 Mutch, Dale R. 1997. Personal Kutztown, Pa. communication. Michigan State Univ.Hickory Corners, Mich. 231 Moynihan, J.M. et al. 1996. Intercropping barley and annual medics. In Cover Crops 241 Mwaja,V.N., J.B. Masiunas and C.E. Eastman. Symposium Proceedings. Michigan State Univ., 1996. Rye and hairy vetch intercrop W.K.Kellogg Biological Station, Battle Creek, management in fresh-market vegetables. Mich. J.Amer.Soc Hort. 121:586-591.

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194 MANAGING COVER CROPS PROFITABLY 309 Shrestha,A. et al. 1996.“Annual Medics.”In 320 Smith, Michael W.1997.Personal communica- Cover Crops: MSU/KBS (factsheet packet). tion. Oklahoma State Univ.,Stillwater Okla. Michigan State Univ.Extension. East Lansing, Mich. 321 Snider, Joe et al. 1994. Cover crop potential of white clover: Morphological characteristics 310 Sideman, Eric. 1991. Hairy vetch for fall and persistence of thirty-six varieties. Mississippi cover and nitrogen:A report on trials by MOFGA Agricultural and Forestry Experiment Service in Maine. Maine Organic Farmer & Gardener Research Report 19:1-4. 18:43-44. 322 Stark, Jeffrey C. 1995. Development of 311 Sims, James R. 1980. In Timeless Seeds. sustainable potato production systems for the “Seeding George black medic,”“George Black Pacific NW.Project report #LW91-29.Western medic in rotation,”“George black medic as a Region SARE. Logan, Utah. green manure.”Conrad, Mont. 323 Stiraker, R.J. et al. 1995. No-tillage vegetable 312 Sims, James R. 1982. Progress Report. production using cover crops and alley crop- Montana Ag.Extension Service. Research Project ping. pp.466-474. In Soil Management in #382. Bozeman, Mont. Sustainable Agriculture. Proc.Third Int’l Conf. on Sustainable Agriculture. 31 August to 4 313 Sims, James R. 1988. Research on dryland September 1993.Wye College, University of legume-cereal rotations in Montana. Montana London, UK. State Univ.Bozeman, Mont. 324 Stivers, L.J. and C. Shennan. 1991. Meeting the 314 Sims, James R. et al. 1991.Yield and bloat haz- nitrogen needs for processing tomatoes through ard of berseem clover and other forage legumes winter cover cropping. J. Prod Ag. 4:330-335. in Montana. Montana AgResearch 8:4-10. 325 Stoskopf. Barley.Univ.of Calif. SAREP 315 Sims, James R. 1995. Low input legume/- Cover Crops Resource Page. http://www.sarep. cereal rotations for the northern Great Plains- ucdavis.edu/ccrop/ Intermountain Region dryland and irrigated systems. Project Report #LW89-14.Western 326 Stute, James K. 1997. Personal communica- Region SARE. Logan, Utah. tion. Michael Fields Agricultural Institute. East Troy,Wis. 316 Sims, Jim. 1996. Beyond Summer Fallow. Prairie Salinity Network Workshop, June 6, 1996, 327 Stute, Jim. 1996. Legume Cover Crops in Conrad, Mont. Available from Montana Salinity Wisconsin.Wisconsin Department of Agriculture, Control Association, Conrad, Mont. 59425. Sustainable Agriculture Program. Madison, Wis. 27 pp. 317 Singogo,W.,W.J. Lamont Jr. and C.W.Marr. 1996. Fall-planted cover crops support good 328 Stute, J.K. and J.L. Posner. 1995a. Legume yields of muskmelons. HortSci. 31:62-64. cover crops as a nitrogen source for corn in an oat-corn rotation. J. Prod.Agric. 8:385-390. 318 Smith, G.R. 1997. Personal communication. Texas A&M Univ.Overton,Texas. 329 Stute, J.K. and J.L. Posner. 1995b. Synchrony between legume nitrogen release and corn 319 Smith and Sharpley.Sorghum and sudan- demand in the upper Midwest. grass. Univ.of Calif. SAREP Cover Crops Resource Agron. J. 87:1063-1069. Page. http://www.sarep.ucdavis.edu/ccrop/

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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

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198 MANAGING COVER CROPS PROFITABLY Based on interviews with more than 60 farmers in • Put Your Ideas to the Test: How to Conduct eight states, The Real Dirt summarizes practical Research on Your Farm or Ranch methods for ecological soil, pest, disease, crop, This 12-page bulletin, which won a publications greenhouse and livestock management. First award from the American Society of Agronomy, released in 1994, The Real Dirt was edited by outlines how to conduct research at the farm Miranda Smith and members of the Northeast level, offering practical tips for both crop and Organic Farming Association and Cooperative livestock producers, as well as a comprehensive Extension. 1998 reprinting includes completely list of more in-depth resources. (August 1999) updated appendices. Print only,$13.95 plus s/h. • Diversify Crops to Boost Profits and Stewardship The Source Book of Sustainable Agriculture is Join farmers and ranchers who have broadened a comprehensive guide to hundreds of free or mod- the scope of their crop and livestock operations erately priced newsletters, brochures, reports, for higher profits and better stewardship.This books, videos and software. It lists 559 resource 12-page bulletin offers practical information materials, from how to market sustainably grown about how to diversify,featuring methods to vegetables to locating the latest sustainable choose and grow alternative oilseeds, legumes, research findings on the World Wide Web. The cereal grains and other specialty crops. It also 136-page book includes contacts and ordering details how to use cover crops and agroforestry information. Released in 1997. $12 plus s/h. practices such as alley-cropping, windbreaks and buffer strips. (January 1999) Informational bulletins These free bulletins cover specific sustainable How to Order SAN Publications agriculture topics, featuring a combination of Please send your check or purchase order (payable research results and success stories from the field. to Sustainable Agriculture Publications) to: Each includes a comprehensive list of more Sustainable Agriculture Publications, Hills Building, in-depth resources and how to get them. Room 10, University of Vermont, Burlington, VT Download printable versions of the bulletins at 05405-0082. To order by credit card, or for www.sare.org/htdocs/pubs/ information about bulk discounts and rush orders, • ‘Naturalize’ Your Farming System: contact (802) 656-0484; [email protected]. A Whole-Farm Approach to Managing Pests Add $3.95 shipping/handling for the first book This 20-page bulletin helps producers—and or CD-ROM; for 1-9 books, add $0.95 per addition- the educators who work with them—design al book;for more than 9 books,call (802) 656-0484. farm-wide approaches to control pests. It lays Please clearly indicate each item and the quantity, out basic ecological principles for managing along with your mailing address and phone pests and suggests how to apply them to real number. For the first book sent outside North farm situations. (May 2000) America, add $6. For each additional book sent • Reap New Profits: Marketing Strategies for outside North America, add $2. Farmers and Ranchers This 20-page bulletin offers snapshots of the Visit SAN On-Line many alternatives to marketing commodities SAN’s web site at www.sare.org lists sustainable through conventional channels. It describes agriculture grant opportunities, research results, how to break into farmers markets; establish events and contact information for SAN and SARE pick-your-own operations and farm stands; staff. More than 900 individuals with an interest in begin entertainment farming; open a some facet of sustainable agriculture participate in Community Supported Agriculture (CSA) sanet-mg,SAN’s electronic listserv.Sign up on SAN’s farm; join or start a cooperative; sell to web site. restaurants or through mail order and the Internet; and more. (November 1999)

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200 MANAGING COVER CROPS PROFITABLY INDEX A Beneficial insects. See Insect for pest management, 31 Alfalfa, 10, 42, 84, 88, 94 management and sources planting, 51,78 Alkaloids, 60–61, 161 Biomass. See also Organic Buffalo rolling stalk chopper, Allelopathy matter; Residue 32–33 black oats, 159 berseem clover, 88, 90 Burclover. See Medics comparison of species, crimson clover, 100–101 Bur medic. See Medics 45–46, 52–53 field peas, 105–106 hairy vetch, 113 hairy vetch, 112 C oats, 62, 64 legumes, 85 Calcium, 19 rye,70 medics, 126 California. See West sorghum-sudangrass hybrids, oats, 62 Canadian field peas. See Field 81 sorghum-sudangrass hybrids, peas subterranean clovers, 136 81 Canola, 125 sweetclovers, 144 subterranean clovers, 132 Carbon to nitrogen ratio, woollypod vetch, 152, 154 sweetclovers, 140 22–23, 54 Ammonia, 24 Birdsfoot trefoil, 131 field peas, 110–111 Annuals. See also specific cover Blackeye peas. See Cowpeas grasses, 54 crops Black medic. See Medics hairy vetch, 113, 114 grasses, 54 Black oats, 159 legumes, 86 legumes, 85–86 Brassica campestris. See Cereal grains. See Small grains; uses, 54 Rapeseed specific crops Austrian winter peas. See Field Brassica napus. See Canola Cereal rye. See Rye peas Brassicas Choppers/chopping, 32–33, 91, Avena sativa. See Oats cash crops 116, 129, 153–154. See also Avena strigosa. See Oats, black cover crop rotations for, Forage clover. See also 15, 37 Sweetclovers; specific clover B sweetclover overseeding, species. Bacteria. See Disease manage- 146 vs. medics, 125 ment and sources; white clover, 150 mixtures, 135 Microorganisms cover crops for orchards, 14 Barley,58–61 erosion prevention, 11 reseeding, 13 advantages and disadvan- for nematode manage- for weed management, 33 tages, 11, 52–53, 58–59 ment, 32 Clover, alsike clover, 131 crop systems, 41–42 for pest reduction, 10 Clover, arrowleaf, 88 cultural traits, 50 Buckwheat, 54, 77–79 Clover, balansa, 40, 158–159 management, 59–61 advantages and disadvan- Clover, berseem, 87–94 mixes of cover crops, 124, tages, 52–53, 77–78 advantages and disadvan- 145 comparative notes, 79 tages, 52–53, 87–88 performance and roles, cowpea mixtures, 98–99 comparative notes, 94 48–49 cropping systems, 37, 41, 42 crop systems, 34, 36, 89, planting, 51, 59-61 cultural traits, 50 92–94 Barrel medic. See Medics management, 78–79 cultural traits, 50 Bees, 149 performance and roles, inoculant, 92–93 Bell beans, 148, 159 48–49 management, 89–91

INDEX 201 performance and roles, comparative notes, 151 fertilizer cost reduction, 9–10 48–49 cultural traits, 50 field pea seeds, 106 planting, 51, 88-90, 94 management, 148–150 inoculant, 92 Clover, crimson, 100–104 for orchards, 14 lupins, 160 advantages and disadvan- performance and roles, 13, medics, 124 tages, 52–53, 100–101 48–49 oat crops, 62 comparative notes, 104, 122, planting, 51, 148-149 pesticides, 10, 27, 114 158 types, 147 red clover, 127–128, 131 in crop rotations, 13, 35, 89, for vegetable production, 37 seed, 45, 51, 156 109–111 Companion crops. See also sunn hemp, 161 cultural traits, 50 Nurse crops sweetclovers, 140 grazing, 88 annual ryegrass, 55–56 white clover, 149 management, 101–104 berseem clover, 88, 91, 92–94 Cotton crop systems mixtures, 112, 113, 118, 135 cowpeas, 96 cowpeas, 96 performance and roles, crimson clover, 101 crop rotations, 39–40 48–49 oats, 63 field peas, 111 for pest management, 26–27, rye,67 hairy vetch, 117–118 30 sweetclover, 142 pest management, 26–27, planting, 51, 101-104 white clover, 148 28, 29 residue, 91 Conservation strips. See Strip wheat, 74 Clover, red, 127–131 cropping Cover crops. See also specific advantages and disadvan- Corn Belt. See Midwest crops tages, 52–53, 127–128 Corn cropping systems advantages and disadvan- comparative notes, 131 berseem clovers, 89, 92–93 tages for specific crops, for corn>soybean systems, crimson clover, 89, 102 45–46, 52–53 34, 36, 73 fertilizer cost reduction, 9–10 benefits, 9–11 cultural traits, 50 field peas, 111 crop rotations, 34–42 fertilizer cost reduction, 9–10 hairy vetch, 112–113, cultural traits, 44–45, 50 management, 129–131 115–116 performance and roles, performance and roles, medic, 123–124 43–44, 48–49 48–49 planting time, 35 for pest management, 25–33 planting, 51, 129, 131 red clover, 128, 129, 130, 131 planting recommendations, wheat nurse crop, 74 rotations, 34–36, 37–38, 41 45, 51 Clover, rose, 135 selecting cover crop, 14 promising species, 158–162 Clover, subterranean, 132–138 sorghum-sudangrass hybrids, regional species, 43, 47 advantages and disadvan- 80 selection criteria, 12–15 tages, 52–53, 132, 133–134 subterranean clover, 133, for soil fertility and tilth comparative notes, 138 137–138 development, 16–24 cultural traits, 50 sweetclovers, 145 testing on your farm, management, 134–138 wheat, 72 156–158 performance and roles, white clover, 148, 150 Cowpeas, 95–99 48–49 woollypod vetch, 152 advantages and disadvan- for pest management, 31 Costs tages, 52–53, 95–96 planting, 51, 132-135, 138 comparison of species, 44, comparative notes, 99 types and cultivars, 132–133 49 crop rotations, 72, 98–99 Clover, white, 147–151 conventional vs. cover crop cultural traits, 50 advantages and disadvan- systems, 27 management, 96–98 tages, 52–53, 147–148 corn crop systems, 130 mixtures, 82

202 MANAGING COVER CROPS PROFITABLY performance and roles, sweetclovers, 145–146 subterranean clovers, 136 48–49 white clover, 149–150 sunn hemp, 161 planting and seeds, 51, 96-97, Crotalaria juncea. See Sunn sweetclover, 145 99 hemp vegetable production, 37 for vegetable production, 38 Crowder peas. See Cowpeas wheat, 76 Crop residue. See Residue Cultivation white clover, 149, 150 Crop rotations. See also Crop comparison of, 46, 52–53 woollypod vetch, 154 systems cowpeas, 98 Disking. See Tillage berseem clover in, 92–94 in disease management, Drought. See also Soil moisture buckwheat in, 79 29–30 berseem clover, 90 corn-soybean systems, 34–36, field peas, 108 hairy vetch, 114 72–73 hairy vetch, 116 sweetclovers, 140–14 for cotton production, red clover, 129–130 Dryland production 26–27, 39–40 cereal-legume crop rotations, cowpeas in, 98–99 D 40–42 crimson clover in, 102–103 Dairy farming, 14 cover crops, 11 dryland cereal-legume sys- Damping off, 30 field peas, 106, 107, 108–109 tems, 40–42 Data collection for trials, 157 medics, 120, 125 fertilizer application, 10 Decomposition sweetclovers, 139–146, 144, field peas in, 106, 108–109 carbon to nitrogen ratio, 146 foxtail millet in, 160 22–23 Dry matter. See Residue hairy vetch in, 112–113 crimson clover, 103–104 Dutch white clover. See Clover, legumes in, 85 of grasses, 54 white medics in, 121, 123–124 microorganisms in, 17–18, 19 pesticide and herbicide Denitrification, 24 E reduction, 10 Disease management and Economics. See Costs planning, 12–15, 34 sources Egyptian clover. See Clover, red clover in, 128, 130 annual ryegrass, 57 berseem rye in, 66 balansa clover, 158 Eragrostis tef. See Teff sorghum-sudangrass hybrids barley,60, 61 Erosion prevention in, 83–84 berseem clover, 91 annual ryegrass, 55 sunn hemp in, 161 black oats, 159 barley,58 for vegetable production, in corn-soybean system, 36 cover crops, 10–11, 16 36–39 cover crop benefits, 10, 27, medics, 121 winter wheat in, 72–73 29–32 mixtures, 86–87 Crop systems. See also Crop cowpeas, 96, 97–98 performance and roles of rotations crimson clover, 103, 104 species, 44, 48 berseem clover, 92–94 field peas, 108 regional species comparison, cowpeas, 98–99 hairy vetch, 117 47 field peas, 108–111 lupins, 161 rye,66 hairy vetch, 117–118 medics, 125 white clover, 149 incorporating cover crops, oats, 64 winter wheat, 72 13 red clover, 130–131 Establishment. See sorghum-sudangrass hybrids, rye, 57–71 Seeding/seeds, specific cover 83–84 sorghum-sudangrass hybrids, crops subterranean clovers, 81–83, 85 Estrogen, 136 137–138 species comparison, 45–46, 52–53

INDEX 203 F Moyer–no-till rye into sweetclovers, 142, 146 Faba beans. See Bell beans standing vetch white clover, 148 Fagopyrum esculentum. Nordell–early plowing to woollypod vetch, 155 See Buckwheat avoid slugs, 144; sweet- Foxtail millet, 160 Fallow clover-clover mixes, 146; Freedom to Farm Act,98 in dryland production, 40–42 weed management in veg- Frost damage, 152 vs. grain legumes, 109 etables, 38–39 Frostseeding, 129, 143, 148–149 vs. medics, 120 Podoll–sweetclover weevil Fruits. See also Orchards; selecting cover crops for, cycle, 144 Vineyards 12–13 Farming organizations, 170–172 rye for,66 sweetclover rotations, 142, Fava beans. See Bell beans subterranean clovers, 134 144, 145 Feed supplements, 65 Farmer accounts Fertilizer G Alger–perennial medic for for fallow systems, 109 German millet. See Foxtail soil quality,fertility,121 red clover systems, 128, 130, millet Anderson–woollypod vetch 131 Grain rye. See Rye reseeding, 153; as frost reducing, 9–10, 93 Grains. See Small grains; specific protectant and recognizing for subterranean clover, 136 crops seedlings, 152 Fescue, 81, 114, 115 Grasses Bartolucci–establishing Field peas, 105–111 carbon to nitrogen ratio, 23, 54 woollypod vetch, 153 advantages and disadvan- for fertilizer reduction, 10 Bennett–rye for weed man- tages, 52–53, 105–107 for moisture conservation, 11 agement in soybeans, 67 cropping systems, 34, 41 for nematode management, Burkett–winter peas for dis- cultural traits, 50 32 ease suppression, 108 for fertilizer reduction, 10 nitrate conservation, 18–19 Carter–wheat production, 74 for grazing and nitrogen, 110 in soil health, 17, 18, 24 de Wilde–killing rye, 69; rye management, 107–111 subterranean clover for mulch, 70 performance and roles, mixtures, 134 Erisman–timing rye kill, 69 48–49 Grass waterways, 57 French–cowpeas in rotation, planting and seed, 51, 106- Grazing 98 108, 111 annual ryegrass, 56, 57 French–field peas, 110 Flail choppers for sorghum- berseem clover, 88, 90 Granzow–sweetclovers for sudangrass hybrids, 82, 83 in corn-soybean system, 41 grazing and green manure, Flail mowers. See cowpeas, 96 142 Mowers/mowing crimson clover, 104 Groff–incorporating rye seed Flax, 42 in dryland cereal-legume 68; killing rye, 69 Forage systems, 42 Guenther–crimson-berseem berseem clover, 88, 90, 91 field peas, 106, 110, 111 clover with corn, 89 cowpeas, 96 grass cover crops, 54 Kirschenmann–sweetclover field peas, 106, 110 hairy vetch, 119 with nurse crops, 145 hairy vetch, 119 livestock poisoning, 81, 85, LaRocca–barley in vineyard medics, 121, 126 139–140, 142 mix oats, 64–65 lupins, 161 Matthews–white clover in red clover, 131 medics, 121 contour strips, 149 rye,71 oats, 64–65 Mazour–managing sweet- sorghum-sudangrass hybrids, performance and roles of clover escapes, 146 81 species, 44, 48 subterranean clovers, 136 rye,71

204 MANAGING COVER CROPS PROFITABLY sorghum-sudangrass hybrids, for medics, 121, 125 woollypod vetch, 152 85 for oilseed species, 145 Integrated Pest Management subterranean clovers, for red clover, 129–130 (IPM), 28–29, 95–96 134–135, 136 for rye, 67, 70 Interseeding sweetclovers, 139–140, 141, for sorghum-sudangrass barley,60 142, 144, 146 hybrids, 82 in corn-soybean system, 36, wheat, 76 for subterranean clovers, 41 Greenchopping berseem 135, 138 cowpeas, 96 clover, 91 for sweetclovers, 144 in dryland cereal-legume Green fallow systems, 145 for wheat and potatoes, 75 crop rotations, 37 Green manures for white clover, 150 legumes and cereal grains, 12 berseem clover, 88, 89, High chopping woollypod medic, 89, 121 90–91, 94 vetch, 153–154 performance and roles of cowpeas, 95 Hordeum vulgare. See Barley species, 44, 49 field peas, 106, 109 Hubam. See Sweetclovers subterranean clovers with oats, 63 Humus. See Organic matter wheat, 137 red clover, 127 sweetclover and corn, 145 subterranean clovers, 133 I in vegetable crop rotations, sweetclovers, 140, 142 Inoculants, 45, 51, 92–93, 149, 37 Groundwater, 109 156, 158 IPM. See Integrated Pest Insecticides, 26–27 Management H Insect management and Irrigation Habitats. See Insect manage- sources barley,60 ment and sources annual ryegrass, 57 potatoes with wheat, 75 Hay barley,61 subterranean clovers, 136 annual ryegrass, 57 bell beans, 159 for underseeding, 12 berseem clover/oats, 88 berseem clover, 91 woollypod vetch, 153, 154 in corn-soybean system, 41 buckwheat, 78, 79 Italian ryegrass. See Ryegrass, cowpeas, 96 cotton, 40 annual crimson clover, 104 cover crops for reducing, 10, medic/grass mixtures, 25–29, 30–31 K 124–125 cowpeas, 95–96, 97, 104 Killing and controlling, 57 oats, 64–65 crimson clover, 101, 103 annual ryegrass, 56–57 sweetclovers, 141 field peas, 106 barley,60 Health and safety issues, 11 hairy vetch, 117 berseem clover, 91 Hemp, sunn, 161 lupins, 161 cowpeas, 97 Herbicides medics, 122 crimson clover, 103 for annual ryegrass, 57 oats, 64 field peas, 108 for berseem clover, 91 red clover, 128 hairy vetch, 115–116 buckwheat sensitivity to, 79 rye,70 medics, 124 in corn production, 26–27 sorghum-sudangrass hybrids, oats, 64 in cotton production, 40 82, 83 red clover, 129–130 cover crops for reducing, 10 species comparison, 45–46, rye, 69–70 for cowpeas, 97 52–53 subterranean clovers, 135 crimson clover and, 101, 103 subterranean clovers, 134 sweetclovers, 143–144 for foxtail millet, 160 sweetclovers, 141, 144–145 white clover, 149 for hairy vetch, 116 wheat, 76 winter wheat, 76 white clover, 149, 150

INDEX 205 L advantages and disadvan- oats, 63 Labor, 39 tages, 52–53, 119–123 red clover, 129–130, 130 Ladino clover. See Clover, white comparative notes, 125, 138 rye, 66, 69, 70 Lana vetch. See Vetch, crop systems, 41, 89 sweetclovers, 141, 142 woollypod cultural traits, 50 top species for, 47 Leaching, 11, 18–19. See also management, 123–125 winter wheat, 73 Nitrogen management and performance and roles, Millets, 131, 160 sources 48–49, 121 Mixtures/mixed seeding. See Legumes. See also specific planting and seeding, 51, also Companion crops; crops 122-123, 125–126 Nurse crops benefits, 85–86 Medigo spp. See Medics annual ryegrass, 56 carbon to nitrogen ratio, 23 Medium red clover. See Clover, barley,59–60 in crop rotations, 14, 37, red benefits, 86–87 40–42, 108–111 Melilotus alba. See berseem clover, 92–94 erosion prevention, 10–11 Sweetclovers carbon to nitrogen ratio, 23 humus production, 17 Melilotus officinalis. See cowpeas, 98–99 mixtures, 62–63, 72–73 Sweetclovers crimson clover, 103 mycorrhizae, 19 Microorganisms field peas, 105 nitrogen fixation and release, humus production, 17–18, 19 hairy vetch, 112, 113–114, 9, 20–21, 92–93, 130, 148 nitrogen fixation, 20–21 118 for pest management, 26–27, plant surface, 29–30 medic, 124–125 33 rhizobium bacteria, 92–93 red clover, 128 Lentils, 41 Mid-Atlantic rye, 67, 68, 69 Ley cropping subterranean crimson clover, 103 sorghum-sudangrass hybrids, clovers, 136 field pea crop systems, 108, 82 Ley system, medics for, 122, 124 111 wheat, 74 Livestock poisoning, 81, 85, hairy vetch, 112–113, 115, Mow and blow system, 94 139–140, 142 116, 118 Mowers/mowing Living mulches rye, 66–71 berseem clover, 90–91, 94 for soil improvement, 13 subterranean clovers, 133, buckwheat, 78 for weed management, 33 137–138 cowpeas, 97 white clover, 148, 149–150 sweetclovers, 146 fescue, 114 Lolium multiflorum. See top species for, 47 flail Ryegrass, annual vegetable production, 37, for berseem clover, 91 Lotus corniculatus. See 38–39 for cowpeas, 97 Birdsfoot trefoil weed management, 33 hairy vetch, 116 Lupins, 160–161 winter wheat, 73 hairy vetch, 115–116 Lupinus albus. See Lupins Midwest insect management, 29 Lupinus angustifolius. See berseem clover, 89–90, 91, medics, 121 Lupins 92–94 red clover, 129–130, 131 buckwheat, 79 rye,69 M in corn-soybean system, 36 sicklebar Malting barley,10 cowpeas, 98 cowpeas, 96 Mammoth clover. See Clover, crimson clover, 103 hairy vetch, 116 red field peas, 110 sorghum-sudangrass Management. See specific hairy vetch crop systems, hybrids, 82, 83 aspects of management 113, 115 sorghum-sudangrass hybrids, Medics, 119–126 medics, 120, 123–125 80–81, 82

206 MANAGING COVER CROPS PROFITABLY subterranean clovers, 133, cover crop effect on humus production, 17 137 conservation and leaching, management, 54 sweetclovers, 143, 144, 146 11, 18–19 nitrogen, 18–19, 54 white clover, 149–150 legume fixation and uses, 54 woollypod vetch, 153–154 release, 20–21 Northeast Mucuna deeringiana. See organic matter, 17 buckwheat, 79 Velvetbeans potential losses, 23–24 crimson clover, 102 Mulches. See also Living regional species field pea crop systems, 108 mulches comparison, 47 hairy vetch, 116 hairy vetch, 117–118 species comparison, 43, 48 oats, 63 rye, 70–71 in specific crops, 14–15 rye,66 sorghum-sudangrass hybrids, tillage systems, 21–23 sorghum-sudangrass hybrids, 82 cowpeas, 95, 98 80–81, 82, 83–84 subterranean clovers, 133 crimson clover, 100, 101, top species for, 47 for weed management, 102, 103 vegetable production, 37 32–33 in crop rotations Northern Plains woollypod vetch, 151–152 corn-soybean system, 36 berseem clover, 91 Mycorrhizae, 19, 140 dryland cereal-legume crimson clover, 102 systems, 42 field pea crop systems, 106, N vegetable production, 38, 107, 108–109 Nematodes 39 medics, 119–122 annual ryegrass, 57 field peas, 106, 109–111 subterranean clovers, 138 balansa clover, 158 grasses, 54 sweetclovers, 143, 144, 145, barley,60, 61 hairy vetch, 112–113, 115, 146 berseem clover, 91 116 Northwest. See Pacific black oats, 159 legumes, 85–86 Northwest cowpeas, 96, 97–98 lupins, 161 No-till systems. See also Tillage crimson clover, 104 medics, 120, 121, 124 corn hairy vetch, 117 mixtures, 86 with hairy vetch, 9, management using cover oats, 62 112–113 crops, 10, 27, 30–32 plant counts for estimation, selecting cover crop, 14 oats, 64 130 with subterranean clover, sorghum-sudangrass hybrids, red clover, 127, 129, 130, 131 133 81, 85 rye, 66, 67, 69 cotton production, 40, species comparison, 45–46, sorghum-sudangrass hybrid 117–118 52–53 management, 83–84, 85 cowpeas, 97 subterranean clovers, 136 subterranean clovers, 133, crimson clover, 102, 103 sunn hemp, 161 136, 137, 138 erosion prevention, 10–11 sweetclover, 145 sweetclovers, 140, 143–144, hairy vetch, 114, 115–116, New Zealand white clover. 146 117–118 See Clover, white wheat, 73 for insect management, Nitrogen management and white clover, 147–148, 148, 27–28 sources 150 nitrogen conservation, 18–24 annual ryegrass, 55 winter wheat, 72 sorghum-sudangrass hybrids, bell beans, 159 woollypod vetch, 151–152, 81, 82 berseem clover, 87–93 152 subterranean clovers, 136 calculating amount in cover Nonlegumes. See also specific sweetclovers in grain crop, 22–23 crops stubble, 143

INDEX 207 vegetables, 15 rye,66 Potatoes, 10, 30, 37, 75, 83–84 wheat, 74 sorghum-sudangrass hybrids, Press-wheel drill, 141 Nurse crops 84 Profitability. See Costs annual ryegrass, 55–56 wheat, 73 barley,58–59 woollypod vetch, 152 R berseem clover, 88 Overseeding. See Underseeding Rainfall. See Drought; Soil buckwheat, 78 moisture medics, 123, 125 P Rapeseed, 85, 145 mixtures, 87 Pacific Northwest Reseeding oats, 62–63 sorghum-sudangrass hybrids, balansa clover, 158 rapeseed for sweetclover, 83 barley,60 145 species for, 47 berseem clover, 88 wheat, 74 subterranean clovers, 136 clovers, 13 Nutrients. See Nitrogen; wheat with potatoes, 75 comparison of species, 45, Phosphorus Pasture. See also Grazing 51 in corn-soybean system, 41 in cotton crop rotations, 40 O sorghum-sudangrass hybrids, crimson clover, 100, 103 Oats, 62–65 81 medics, 121–122, 126 advantages and disadvan- Peanuts, 26–27, 29 mixtures, 86 tages, 52–53, 62–63 Pearl millet, 160 subterranean clovers, comparative notes, 61, 65 Peas. See Cowpeas; Field peas 135–136, 137–138 crop systems, 36, 37, 113, Perennials. See also specific sweetclovers, 141 160 crops woollypod vetch, 154 cultural traits, 50 grasses, 54 Residue fertilizer reduction, 9 legumes, 85 berseem clover, 90, 91, 94 management, 63–65 nitrogen fixation, 92 buckwheat, 77 mixtures, 88, 89, 92–94, 143 Pest management. See Disease in corn-soybean system, 35 performance and roles, management and sources; in cotton production, 40 48–49 Insect management and cowpeas, 98 planting, 51, 63-64 sources;Weed management and crimson clover, 103, 104 Oats, black, 159 sources field peas, 111 Orchards Phosphorus grasses, 54 annual ryegrass, 55–57 buckwheat, 77–78, 79 performance and roles of cowpeas, 96 conservation by cover crops, species, 44, 49 insect management, 28–29 19 sorghum-sudangrass hybrids, medics, 120 crimson clover, 101 82, 83, 85 mixtures for, 86 hairy vetch, 114 species comparison, 43, 48 selecting cover crop, 14 red clover leaching, 131 Rhizobium bacteria, 92–93 subterranean clovers, 132, sweetclovers, 140 Rice, 137 133, 136, 137 winter wheat, 72 Rice straw,59 woollypod vetch, 154 Pisum sativum subsp. arvense. Rollers for berseem clover, 91 Organic matter See Field peas Rolling stalk chopper, 32–33, barley,58 Plant counts for nitrogen esti- 116, 129 buckwheat, 77, 79 mation, 130 Rotations. See Crop rotations components, 17 Planting. See Establishment; Runoff reduction, 101 medics, 120–121 Seeding/seeds Rye, 65–71 microorganisms and aggrega- Plastic mulches, 118 advantages and disadvan- tion, 17–18, 19 Potassium, 19, 66, 72 tages, 52–53, 65–67

208 MANAGING COVER CROPS PROFITABLY comparative notes, 71 Setaria italica. See Foxtail vegetable production, 39 crop systems, 34–36, 39, 40, millet wheat, 73, 74 41, 160 Shading, 150 white clover, 148 cultural traits, 50 Small grains. See also specific woollypod vetch, 152 hairy vetch mixtures, 114, crops Soil moisture. See also Drought; 115, 118 berseem clover as compan- Dryland production management, 68–71 ion crop, 91 barley,60 nitrate conservation, 11, for corn-soybean systems, in corn-soybean systems, 35 18–19 35–36, 41 cover crops for conserving, performance and roles, erosion prevention, 11 11 48–49 fertilizer reduction, 10 cowpeas, 96, 98 for pest management, 26–27, field pea mixtures, 105, field peas, 106, 109, 111 30, 32, 70–71 107–108 foxtail millet, 160 planting and seed, 51, 67-68, humus production, 17 hairy vetch, 114 71 interseeding, 12 legumes, 145 Ryegrass, annual, 55–57 medics in rotation, 124 medics, 125 advantages and disadvan- overseeding with berseem mixtures, 86 tages, 52–53, 55–56 clover, 90 in nitrogen fixation, 21 cultural traits, 50 red clover plantings, 129 potatoes with wheat, 75 management, 56–57 selecting cover crop for, 13, rye killing and, 69 vs. perennial, 57 14 subterranean clovers, performance and roles, Small-seeded horse beans. See 132–133, 136, 137 48–49 Bell beans sweetclovers, 146 planting, 51, 56-57 Snail medic. See Medics white clover, 148 for vegetable production, 37 Soil erosion. See Erosion Soil organisms, 24. See also Ryegrass, perennial, 13, 57 prevention Microorganisms Soil fertility and tilth. See also Soil temperature, 21, 130 S Nitrogen management and Sorghum, 133, 136 Safflower, 37–39 sources Sorghum-sudangrass hybrids, Secale cereale. See Rye annual ryegrass, 55 80–85 Seeding/seeds. See also barley,58 advantages and disadvan- Interseeding; Reseeding; buckwheat, 78–79 tages, 52–53, 80–81, 84 specific cover crops cover crops for improving, comparative notes, 80, 84–85 Underseeding 10, 16–24 in corn-soybean system, 41 balansa clover, 158 crop rotations for, 13 cultural traits, 50 bell beans, 159 dryland cereal-legume management, 82–84 black oats, 159 systems, 42 performance and roles, comparison of species, 51 hairy vetch, 113 48–49 in corn>soybean system, 35 red clover, 128 planting and seed, 51, 82, 85 foxtail millet, 160 regional species comparison, for vegetable production, 37, grasses, 54 47 38 lupins, 160 rye,71 Sorgoleone, 81 sunn hemp, 161 sorghum-sudangrass hybrids, South teff, 161–162 81, 84 berseem clover, 90, 91 testing on your farm, species comparison, 43, 48, crimson clover, 101, 102, 103 156–157 52–53 field pea crop systems, 108, Seed suppliers, 166–170 subterranean clovers, 133 109–111, 111 Sesbania mixtures, 82 sweetclovers, 140

INDEX 209 hairy vetch crop systems, advantages and disadvan- woollypod vetch, 153–154 112, 115, 117–118, 122 tages, 52–53, 139, 140–141 Trials on your farm, 156–158 rye, 66, 69 comparative notes, 146 Trifolium alexandrinum. See subterranean clovers, 135, in crop rotation, 72 Clover, berseem 136, 137 cultural traits, 50 Trifolium balansae. See Clover, top species for, 47 management, 141–146 balansa weed management, 33 performance and roles, 13, Trifolium brachycalcycinum. Southern peas. See Cowpeas 48–49 See Clover, subterranean Southern spotted bur medic. planting and seed, 51, Trifolium incarnatum. See See Medics 141-143, 145-146 Clover, crimson Soybeans types, 139–140 Trifolium pratense. See Clover, berseem clover for, 92–93 for vegetable production, 37, red cotton intercropping, 96 38–39 Trifolium repens. See Clover, crop rotations, 34–36, 41 wheat nurse crop, 74 white field pea overseeding, 111 Trifolium subterraneum. See hairy vetch overseeding, 114 T Clover, subterranean medics in, 124 Teff, 161–162 Trifolium yanninicum. See nematode management, 32 Tillage. See also No-till systems Clover, subterranean red clover for, 129, 130 conservation tillage Triticum aestivum. See Wheat, rye for, 66, 67 for disease management, winter wheat for, 72, 74, 75 30–31 Spring oats. See Oats for insect management, U Spring peas. See Field peas 26–27 Undercutters, 32–33, 116, 135 Straw,59 conventional till Underseeding Strip cropping corn and subterranean annual ryegrass, 56 annual ryegrass, 57 clover, 133 berseem clover, 89, 90, 94 berseem clover, 94 nitrogen conservation, in corn-soybean system, 35 in cotton production, 40 18–24 crimson clover, 102 cowpeas, 97 organic matter accumula- in crop rotation, 12–13 rye,66 tion, 18 field peas, 111 white clover, 150 cotton and peanuts, 26–27 hairy vetch, 114 Subclover. See Clover, field peas, 108 medics, 123–124, 124–125, subterranean oats, 64 126 Subsoil looseners, 47, 52–53, reduced tillage for rye, 71 oats, 63 80–81 ridge-till for medics in corn, red clover, 128, 129 Sudangrass, 83. See also 124 rye,66 Sorghum–sudangrass hybrids rotary tillage for white sweetclovers, 142, 145, 146 Sudax. See Sorghum-sudangrass clover, 150 for weed management, 33 hybrids sorghum-sudangrass hybrids, wheat, 73 Sudex. See Sorghum-sudangrass 82, 83 white clover, 148 hybrids strip-till Universal Soil Loss Equation, 16 Sugarbeets, 10, 32, 59, 60 corn and peanuts, 26–27 Sunflowers, 145 crimson clover, 102 V Sunn hemp, 161 for insect management, Vegetables Sustainable Agriculture 27–28 annual ryegrass for, 55–57 Network, 198–199 rye,70 berseem clover for, 91, 94 Sweetclovers, 139–146 white clover, 150 in corn-soybean system, 41 sweetclovers, 142, 145–146 cowpeas for, 98

210 MANAGING COVER CROPS PROFITABLY crimson clover for, 102, 103 Vetch, woollypod, 119, 151–155 species comparison, 47, crop rotations, 13, 36–39 advantages and disadvan- 52–53 disease management, 30 tages, 52–53, 151–152 cowpeas, 95, 99 foxtail millet for, 160 comparative notes, 155 foxtail millet, 160 hairy vetch for, 116, 117, 118 cultural traits, 50 hairy vetch, 113 insect management, 27–29 management, 152–155 medics, 120, 124 medics for, 125 performance and roles, oats, 62, 63, 64 rye for, 66, 68, 70–71 48–49 rye, 66–67, 70 selecting cover crop, 15 planting, 51, 151-155 sorghum-sudangrass hybrids, sorghum-sudangrass hybrids, for vegetable production, 81, 82, 84, 85 81, 83 37–39 subterranean clovers, 133, subterranean clovers for, 133, Vicia dasycarpa. See Vetch, 137–138 134, 136, 137–138 woollypod sweetclovers, 146 sweetclover overseeding, 146 Vicia faba. See Bell beans teff, 162 white clover for, 148, Vicia villosa. See Vetch, hairy vegetable production, 37, 149–150 Vicia villosa ssp. dasycarpa. See 38–39 woollypod vetch for, 152 Vetch, woollypod wheat, 73, 74–75 Velvetbeans, 99 Video resources, 165 white clover, 150 Vetch, 87, 159 Vigna unguiculata. See woollypod vetch, 152, 154 Vetch, bigflower, 70 Cowpeas West Vetch, cahaba white, 31 Vineyards barley,58 Vetch, common, 37–39, annual ryegrass for, 55–57 berseem clover, 90 109–111, 155 barley for, 59–60, 61 buckwheat, 79 Vetch, hairy,112–119 buckwheat for, 79 cowpeas, 95–96 advantages and disadvan- cowpeas for, 96 field pea crop systems, tages, 52–53, 112–114 medics for, 120 107–108 comparative notes, 155 sorghum-sudangrass hybrids, hairy vetch, 112 for corn-soybean systems, 84 medics, 120, 123–124, 126 34–36, 41, 72 woollypod vetch for, 151, subterranean clovers, crop systems, 117–119 153–154 133–138 cultural traits, 50 Virus. See Disease management top species for, 47 fertilizer reduction, 9–10 and sources vegetable crop systems, management, 114–117 37–39 performance and roles, W woollypod vetch, 151–155 48–49 Water quality,11 Wheat, winter, 72–76 for pesticide reduction, 10 Weed management and sources advantages and disadvan- planting and seed, 51, annual ryegrass, 55, 57 tages, 52–53, 72–73 114-119 barley,58, 60–61 berseem clover as residue, 91 berseem clover, 88 companion, 94 rye mixtures, 68 black oats, 159 crop rotations, 36, 41–42, in small grain production, 14, buckwheat, 77 160 109–111 cotton production, 40 cultural traits, 50 strip cropping with wheat, cover crops management, 73–76 94 management using, 27, medic plantings and, 120, for vegetable production, 39 32–33 121, 124–125 Vetch, purple, 37–39, 155 performance and roles of performance and roles, species, 44, 48 48–49

INDEX 211 for pest management, 30 planting and seed, 51 red clover plantings, 129, 130 subterranean clover interseeding, 137 sweetclover rotations, 140, 142, 144 for vegetable production, 37 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

212 MANAGING COVER CROPS PROFITABLY SUSTAINABLE $19.00 Managing Cover Crops Profitably AGRICULTURE NETWORK THE NATIONAL OUTREACH ARM OF USDA-SARE Managing Cover HANDBOOK SERIES SECOND Managing Cover Crops Profitably BOOK 3 Crops Profitably EDITION SECOND EDITION

armers 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 F 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 EDITION SECOND 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 partic- NetworkAgriculture ularly impressed with the way information is supported by personal experiences of

farmers and researchers.” Sustainable John R.Teasdale, research scientist, USDA-ARS, Beltsville, Md.

ISBN 1-888626-04-6 SUSTAINABLE AGRICULTURE NETWORK THE NATIONAL OUTREACH ARM OF USDA-SARE A publication of the Sustainable Agriculture Network with funding by the Sustainable Agriculture Research and Education program of the CSREES, 9 781888 626049 U.S. Department of Agriculture USDA Plant Hardiness Zone Map

AVERAGE ANNUAL MINIMUM TEMPERATURE

Temperature (ûC) Zone Temperature (ûF)

-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

Agricultural Research Service, USDA

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).

Source: Bailey,1994