Vegetables

Midwest Cover Crops Council (MCCC-129)

University of Guelph (SAG-FS-21-003)


This publication is intended to provide a starting point for farmers who are new to growing cover crops. With experience, many farmers fine-tune the use of cover crops for their systems.

Introduction

This recipe provides an introductory approach to integrating a cover crop mix of oats and radish after an early harvested processing vegetable, such as snap beans, cucumbers, peas, or early tomatoes. Both oat and radish can successfully establish in late summer to early fall and usually winter-kill. It is a low-risk mix that will help control tough perennial or winter annual weeds, minimize erosion, build soil structure, reduce compaction, and add some extra diversity to your rotation.

Planning and Preparation
  • Planning—Keep it simple. Start small on one field. Be timely. Prioritize cover crop management based on your goals. Fine-tune the recipe for your needs over time. If cole or other Brassica crops are grown in the rotation, it’s best to use peas instead of radish in order to avoid a buildup of pest pressures.
  • Vegetable planting—No modifications to the crop are required for the successful use of cover crops.
  • Residual herbicides—Oats and radish are tolerant of most herbicides applied to the vegetable crop in-season.
  • Seed purchase—Seed supplies and prices can vary depending on the time of year; it is good practice to order seed early (before harvest). The Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) has compiled a list of reputable cover crop seed suppliers (see Resources).
  • Fertility or manure—Fall fertilizer incorporation can damage the living cover crop. Plan for fertilizer or manure application before planting the cover crop or after the cover crop winter-kills, or use a low-disturbance injection method to minimize damage.
Summer/Fall Work
  • Vegetable harvest—Ensure that crop residues are spread evenly. Some light tillage can help with residue breakdown under the cover crop canopy. If the field was heavily tracked or rutted during harvest, level the field with tillage. For early harvested vegetables, such as peas, waiting a few weeks may allow for breakdown of crop residues and improve the seedbed for the cover crop.
  • Timing of planting—Plant the oat-radish mix between mid-August and mid-September. Planting radish prior to August is not recommended as it will often result in flowering and seed production instead of quick coverage and biomass accumulation.
  • Seeding rate in oats/radish mix—Mix seeds prior to planting. For oat, use 30–60 lbs/acre. Use the higher end of that range if manure application and/or erosion control are your goals; the lower end of that range should be sufficient if you want to build soil structure or have land covered. Radish should be seeded at no more than 2 lbs/acre if drilling and 2–3 lbs/acre if broadcasting.
  • Planting method—An oat-radish cover crop can be planted with a drill at a depth of 0.50–0.75 inch or broadcast with light incorporation. An oat-radish cover crop can also be mixed with dry fertilizer, applied with a spreader, and then lightly incorporated.
  • Fertility or liming—After most processing vegetables, extra nitrogen (manure or fertilizer) is not required. Use a current soil test (no older than four years) to determine lime or phosphorus and potassium nutrient requirements for the next year’s crop. Fertilizers can be applied at the same time as seeding to reduce costs. Lime should be applied separately as it will need to be incorporated deeper than the cover crop seed.
  • Manure—Up to 4 tonnes/acre of solid manure or litter can be surface-broadcast to growing oats and radish provided it is evenly distributed; otherwise it should be done prior to seeding. If injecting manure, low-disturbance injectors are available that will minimize damage to oats and radish. See Use and Management of Manure and Other Organic and/or Prescribed Materials in Resources for more information about recommended practices in Ontario.
  • Tillage or no-tillage—The cover crop can be established with no tillage, but light tillage can help suppress weeds to allow the cover crop to get established. Fall full-width tillage is not necessary and minimizes the benefits of soil cover over the winter.
Figure 1. This shows a well-established oat-radish mix. Radish is very competitive; do not use more than 2 lbs/acre if drilling and 2-3 lbs/acre if broadcasting in a mix with oats. (OMAFRA)
Spring Work
  • Fertilizer—No modifications to a typical fertilization program are required after an oat-radish cover crop mix.
  • Termination—Both oats and radish should winter-kill. However, mild winters and good snow cover sometimes allow overwintering of radish. If this occurs, it is easily terminated with a typical pre-plant herbicide application for broadleaf weeds.
  • Direct-seeding—Most modern planters are fully capable of planting corn, soybean, or vegetables into the expected low spring-residue cover from an oat-radish mix. But if direct-sowing vegetables, consider strip or zone tillage to prepare the seedbed. Check planting depth and seed furrow closure shortly after beginning to plant as some adjustments may be needed.
  • Transplanting—Scout fields early and adjust timing of operations accordingly. An oat-radish cover crop reduces winter annuals, such as chickweed, so tillage for weed control may not be necessary. Cover crop residues can slow the early spring drying and warming of the soil, particularly for early crops such as cole crops; it is unlikely to affect warm-season crops such as tomatoes.
  • Scouting—After planting, scout for crop emergence and population. Additionally, scout for weeds since cover crop residue on the soil surface can delay the emergence of annual weeds, which may delay the application of post-emergence herbicides.
Resources

Cover Crop Selector Tool —available from Midwest Cover Crops Council

Best Management Practices: Winter Cover Crops (OMAFRA)

Cover Crop Seed Suppliers (OMAFRA)

Use and Management of Manure and Other Organic and/or Prescribed Materials (Ontario Soil and Crop Improvement Association Infosheet #17)

Guide to Weed Control: Hort Crops (OMAFRA publication 75B)

Vegetable Crop Protection Guide (OMAFRA publication 838)

Vegetable Production Information—Commercial Vegetable Production (OMAFRA)

Authors

Jordan Grigg, Cameron Ogilvie, and Laura Van Eerd, University of Guelph; and Anne Verhallen, OMAFRA (Note: This publication was adapted with consent from MCCC under a joint project to produce customized introductory guidance about cover crops for all member states/provinces.)

Reviewers and Contributors

Kris McNaughton, University of Guelph, and Elaine Roddy, OMAFRA

The Midwest Cover Crops Council (midwestcovercrops.org) aims to facilitate widespread adoption of cover crops throughout the U.S. Midwest and Ontario by providing educational/outreach resources and programs, conducting new research, and communicating about cover crops to the public.
Funding for this project was provided by McKnight Foundation.

November 2021

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. ©2021 by MCCC. All rights reserved.

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Midwest Cover Crops Council (MCCC-126)


This publication is intended to provide a starting point for farmers who are new to growing cover crops. With experience, farmers may fine-tune the use of cover crops for their systems.

Introduction

A canning or processing crop such as green bean, sweet corn, or pea is harvested early or by midsummer and offers an excellent window to get adequate cover crop growth before any following crop. Cover crops following canning crops will protect soil from erosion and improve soil structure after heavy harvesting equipment is used to take off the canning crop. Some canning crops leave significant residual nitrogen (N) in the soil that is vulnerable to leaching, and a cover crop can retain that soil N for future crops. Since growers follow canning crops with any number of different rotations, a fast-growing species such as oats mixed with a light seeding of radish is a safe choice as both will winter-kill. With this combination, no spring termination is needed, and there is little chance of tying up N for the following year.

Planning and Preparation
  • Planning—Educate yourself. Go to field days, learn from farmers who are currently planting cover crops, read about cover crops, check out cover crop research results from local universities, and work with your local Natural Resources Conservation Service (NRCS) and Soil and Water Conservation District (SWCD). Identify your goals in planting a cover crop as these will drive many decisions. Start small, and choose a field that has low weed pressure to create the best conditions for success. Consult with your crop insurance representative to ensure planned practices will not affect your insurance coverage.
  • Canning crop management—Follow best management practices regarding fertility and weed management, and make sure to notify the canning company that you’re planning on a cover crop after a canning crop harvest.
  • Residual herbicides—Commonly used herbicides can negatively impact cover crop establishment, so check the history of herbicide application for your field. Oats can tolerate many preemergence and postemergence herbicides. However, if the oats/radish biomass is to be grazed or used for feed or forage, you must follow the rotational crop restrictions listed on the label of any applied herbicides. Rotational restrictions should be checked for herbicides used in the current and previous cropping season if the cover crop is to be grazed or used for feed or forage. (See Using Herbicides and Cover Crops in Corn and Soybean in Resources.)
  • Seed purchase—Order cover crop seed early from a reputable source. If you grow your own, get it tested for germination, purity, and weed seed. Named varieties can produce more growth and have more predictable development, but they are usually more expensive than VNS (variety not stated) seed. Use good quality seed that has been cleaned and tested for germination and weed seed contamination. Utilize local sources of seed as much as possible to help prevent the introduction of invasive noxious weeds such as Palmer amaranth.
  • Fertility or manure—Fall fertilizer incorporation could damage the cover crop and destroy any structure gained, so plan to apply any needed fertility after the cover crop has winter-killed. If manure will be applied in the fall, use low-disturbance injectors to minimize damage to the cover crop.
Summer/Fall Field Work
  • Timing of cover crop planting—After canning crop harvest, some light tillage may be necessary to create a seedbed for the cover crop. Using a leveling tool such as a vertical tillage bar with an air seeder on top allows for tilling and seeding the cover crop at the same time. Try to time seeding when rain is in the forecast, or if you use irrigation, you can water in the seed for reliable establishment.
  • Planting method—Drill the seed to a depth of 0.75 inch, or broadcast the seed with a shallow incorporation to less than 1 inch to allow for good seed-to-soil contact and enhanced establishment.
  • Seeding rate—For oats, a minimum seeding rate of 21 lbs./acre of pure live seed (PLS) is suggested when seed is drilled or incorporated. The seeding rate should be increased to a minimum of 45 lbs./acre of PLS if broadcast. For radish, the rate is 1.2 lbs./acre if drilled or incorporated, and 1.7 lbs./acre if broadcast. These rates are based on a mixture of 70% oats–30% radish. If another ratio is desired, rates should be adjusted using the Minnesota Cover Crop Design Tool (see Resources).
  • Tillage—No fall tillage is needed. The oat/radish residue will freeze, then decompose over the winter, and a cash crop such as field corn or soybeans can be no-tilled into the residue if you wish. While full-width tillage may be used in the spring, this will reduce soil structural improvements the cover crop provided over the winter.
  • Future considerations—An oat/radish mixture is promoted here as the entry-level cover crop mixture post-canning crop. In future years, you may consider grasses that survive the winter (e.g., winter rye or triticale) for spring erosion control or legumes (e.g., crimson clover, which winter-kills, or red clover, which survives the winter) to supply N to the next cash crop. However, both of these options will have separate considerations and management recommendations. Use the Cover Crop Selector Tool (see Resources), or visit with local representatives of NRCS or Extension for more specific information on seeding other species.
Figures 1 and 2: An oat-radish mixture planted Aug. 25 in Dakota County, MN, pictured on Sept. 24 (top) and on Oct. 14 (bottom). (Ashley Gallagher, Dakota SWCD)
Spring Work
  • Scouting—In the spring, scout the remaining cover crop residue, and note whether any oat seed that remained dormant over the winter begins to sprout in the spring. Any grass-target herbicide should take care of these escapes.
  • Cash crop planting—Most modern row planters are fully capable of planting corn or soybeans into residue from a dead oat/radish cover crop. Row cleaner attachments may be beneficial. Check planting depth and seed furrow closure shortly after beginning to plant in case any planter adjustments are needed, such as increasing down pressure to move through increased residue.
  • Scouting after planting—After planting, scout for emergence and population as well any insect, disease, or weed pressure.
Resources

University of Minnesota Extension Cover Crop website

Cover Crop Selector Tool —available from Midwest Cover Crops Council

Minnesota NRCS Resources, including Minnesota Cover Crop Design Tool

USDA-NRCS Cover Crop Termination Guidelines

Using Herbicides and Cover Crops in Corn and Soybean (University of Minnesota Extension)

Authors

Anna Cates, University of Minnesota Extension; Ashley Gallagher, Dakota Soil and Water Conservation District (Minnesota); Steve Lawler, Mower Soil and Water Conservation District (Minnesota); and Matt Ruark, University of Wisconsin–Madison Division of Extension

Reviewers and Contributors

Carl Rosen, University of Minnesota; Ken Schroeder and Dan Smith, University of Wisconsin–Madison Division of Extension; and Carissa Spencer, Minnesota NRCS

The Midwest Cover Crops Council (www.https://www.midwestcovercrops.org) aims to facilitate widespread adoption of cover crops throughout the Midwest by providing educational/outreach resources and programs, conducting new research, and communicating about cover crops to the public.
Funding for this project was provided by McKnight Foundation.

March 2021

The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or a part of an individual’s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA’s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410 or call (800) 795-3272 (voice) or (202) 720-6382 (TDD). USDA is an equal opportunity provider and employer. ©2021 by MCCC. All rights reserved.

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