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South Dakota Cover Crop Recipe – Post Small Grains, Going to Soybean or Corn: Use a Cool-Season Mix

Midwest Cover Crops Council (MCCC-135)

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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

The following recipe provides an introductory approach to integrating a cover crop into a wheat-based rotation with soybean or corn. Planting a cover crop blend that predominantly consists of cool-season species and is winter-killed adds diversity and provides soil armor through summer and spring. However, in some situations added ground cover in the spring in combination with excess soil moisture could be a problem unless winter cereals (winter rye, wheat, or triticale) are included in the mix.

Planning and Preparation
  • Planning—Consult with university Extension staff, local NRCS staff, and experienced producers to gain insight on the practice. Start small while exploring new practices. In South Dakota, timeliness is important due to the shorter growing window. Always focus on your objectives, such as whether you are growing the cover crop for ground cover, fall grazing, nutrient cycling, etc.
  • Small-grain variety and planting—Small-grain varieties such as wheat or oats do not need to be changed or modified to incorporate cover crops following grain harvest or haying. Planting small grains early in the spring is important for good growth and development, which also typically results in earlier harvest and allows more time for cover crops to grow before a frost.
  • Residual herbicides—A blend consisting primarily of cool-season cover crops such as cereal grains (oat, barley), brassicas (radish, turnip, rapeseed), and legumes (field pea), and some warm-season grasses such as millet and sorghum-sudangrass have shown good tolerance to commonly used herbicides. If the cover crop is intended for grazing in the fall/winter, it is critical to follow grazing restrictions stated on the herbicide label.
  • Seed source—Planning ahead and ordering seed early with the objective in mind is important. Most cover crop seed dealers have their own pre-mixed blends but are willing to custom-mix upon request. Follow the seed label and review the individual species to make sure that the growth habit of each is ideal for the planting time. If opting for a mix of only one or two species, labeled varieties usually perform better than variety not stated (VNS) seeds.
Summer/Fall Work
  • Harvest—Harvest wheat/oats at the normal time. If weed pressure is high, you can spray glyphosate or other herbicides with the least residual effects. Herbicides are a better option than tillage as stirring the soil can dry it out and reduce germination. Baling small-grain residue is common in South Dakota but can make establishment of the cover crop difficult where the windrows were present.
  • Timing of planting—In South Dakota, wheat and/or oats are generally harvested from the second week of July to the first week of August. Planting cover crops immediately following harvest is recommended so that the seasonal window can be maximized. A mix consisting mostly of cool-season annual species grows well as temperatures start to gradually decrease. Use the Cover Crop Selector Tool (in Resources section) for precise seeding dates.
  • Planting method—Determining seeding depth is tricky when planting a mix with various seed sizes. Drilling to a moderate depth of 0.50–0.75 inch will be good for most mixes. Tilling or soil disturbance is not recommended as this may cause unwanted weed growth.
  • Cover crop types—Diversity of species in a mix is good and typically will provide the best benefits. The general rule of thumb is to select cover crops that are of contrasting growth habit to the subsequent cash crop. For example, if the next season’s cash crop is corn, planting cover crop blends that have a higher proportion of cool-season broadleaves is suggested; if the next season’s crop is soybean, then a mix with more cool-season grasses would be ideal. If wheat or other small grains are to be raised for seed purposes, cover crop blends that contain winter cereals (e.g., winter wheat, winter rye, winter triticale) are not suggested.
  • Seeding rate—Seed size and proportion in the mix determines the seeding rates. For example, a mix high in large-seed species such as peas and oats can be higher than the ones dominant in brassicas. Typically, the seeding rate of commonly marketed cover crop mixes can range from 15 to 30 lbs./acre. The full seeding rate of individual species can be found in Cover Crop: Common Species and Properties of South Dakota (see Resources).
  • Tillage—Tillage or soil disturbance is not suggested.
  • Fertility—Fertilizer is not usually required for a cover crop mix with well-balanced species. However, producers who have livestock and intend to maximize growth for fall/winter grazing have shown interest in using low rates of fertilizer. Although there are no specific guidelines on fertilizer rates for various cover crop blends, using nitrogen rates in the range of 30–40 lbs. N/acre can enhance cover crop growth and establishment, especially following high-yielding wheat crops.
  • Grazing—Producers who prefer to grow cover crops after small grains for grazing in the fall/winter can slightly increase the proportion of cool-season grass species such as oats and barley. Include at least 60% grasses in the mix for grazing. To assist in calculating the amount of grazing your cover crop can offer, refer to the Grazing Cover Crop Calculation App (in Resources).
Figure 1: Frost-killed cover crops seeded after oats in southeast South Dakota (Peter Sexton)
Spring Work
  • Starter fertilizer—No modifications to your typical fertilization program are required for planting soybean or corn. However, there are a few considerations for planting corn. After a cover crop has winter-killed, get a current soil test to look at nitrates and sulfur. Cover crops can sequester nitrogen, which is a desired attribute to reduce leaching or runoff. But mixes with a high proportion of Brassica species (radish, turnip, rapeseed) can use quite a bit of sulfur. Soil-testing and applying these nutrients as needed to minimize the chance of nutrient deficiency is a good practice.
  • Termination—Typical cover crop blends should winter-kill in South Dakota. However, mild winters can leave a few plants the next spring. Timely scouting and herbicide application as needed is suggested for uniform control of cover crop plants that survived the winter. Some mixes with winter annuals such as winter triticale, cereal rye, or winter camelina will require spring termination.
  • Soybean or corn planting—It is usually best to no-till plant cash crops into the dead/dry or standing cover crop. Almost all modern planters and drills are fully capable of planting soybean or corn into terminated cover crop residue. Check planting depth and seed furrow closure shortly after beginning.
  • Scouting—After planting soybean or corn, scout for crop emergence and population. Additionally, scout for weeds since cover crop residue can often delay emergence of annual weeds, which may delay the application of post-emergence herbicides.
Figure 2: This photo shows cover crop growth mid-September in Lake County, SD. The field was seeded after cereal rye was hayed in June (David Karki)
Resources

Cover Crop Selector Tool—available from the Midwest Cover Crops Council, www.midwestcovercrops.org

Cover Crop Species Selection for Grazing (USDA-NRCS publication SD-FS-56)

Herbicide Residual Effects on Cover Crops after Wheat (South Dakota State University Extension)

Cover Crop: Common Species and Properties of South Dakota (USDA-NRCS)

Grazing Cover Crop Calculation App (Jotform app)

Author

David Karki, South Dakota State University Extension (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

Eric Barsness, USDA-NRCS; Anthony Bly, South Dakota State University Extension; Eileen Kladivko, Purdue University; Anna Morrow, Midwest Cover Crops Council

The Midwest Cover Crops Council (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.

December 2022

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. ©2022 by MCCC. All rights reserved.

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South Dakota Cover Crop Recipe – Post Corn, Going to Soybean: Use Cereal Rye

MCCC-134

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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

With much attention focused on soil health and crop diversity, interest in cover crops has increased greatly in recent times. Generally, following small grains (after harvest or early season hay crop), a wide range of cover crop species can be selected due to an ample seasonal window for establishment and growth. However, for the row-crop growers who practice a strict corn-soybean rotation, the species selection is limited. Winter rye (cereal rye, Secale cereale L.) has been a go-to cover crop choice among many row-crop growers in the Midwest, including in South Dakota. Some producers have also used winter wheat and/or winter triticale as a cover crop. One of the most important attributes that winter rye possesses over other winter cereals such as winter wheat or triticale is its tolerance to extreme cold temperatures. Further, its rapid early spring growth and allelopathic characteristics, which allow it to suppress tough weeds, have also been favored by producers.

Planning and Preparation
  • Planning—Having a clear objective on why the cover crop is being used is critical as preparation can vary for different uses. For example, depending on the farm situation, cereal rye can also be used for supplemental forage in the spring. Consulting university Extension and NRCS staff, and fellow producers who have been in this practice longer can be of great help. If you are new to the practice, starting small and gradually increasing acres over the years is suggested.
  • Rotation—Planting rye after corn and ahead of soybean is a better fit than after soybean and before corn because soybeans can tolerate later planting in the spring better than corn. This allows rye to accumulate more spring biomass. Studies conducted in southeastern South Dakota have shown no negative impact on soybean yields when planted in late May to the first week of June in fields with preceding rye cover crops. However, in years with below-average precipitation, terminate rye early in the spring so that soil moisture can be preserved for the following soybean crop. The sequence of winter rye within the cropping rotation is crucial for maintaining the agronomic performance of cash crops. When planted after soybean and terminated close to corn planting, rye has shown negative effects on corn yields in South Dakota. However, when rye was terminated at least two weeks prior to planting corn, most of those detrimental effects were negated. More studies are needed to examine the true effects of a rye cover crop on a subsequent corn crop. Growing a cereal grain crop after a cereal rye cover crop is not suggested due to weed control issues and possible contamination of the cereal grain crop.
  • Corn maturity—Do not plant earlier-maturing corn hybrids in an effort to establish rye earlier in the fall. Planting recommended-maturity hybrids maintains the optimal performance of the corn crop and produces higher yields that outweigh any rye biomass gain in the spring.
  • Residual herbicides—Herbicides with a longer residual period can have a significant impact on cover crop establishment and growth. However, cereal rye planted in the fall has shown good tolerance to common herbicides used on corn. Keep in mind the grazing restriction of herbicides used if cereal rye is to be grazed in the winter or the following spring.
  • Seed source—Quality seeds produce quality plants. Acquiring seeds of a known variety from a reliable source increases the chances of better growth and performance. Variety not stated (VNS) seeds are less expensive but can have inferior growth.
Fall Work
  • Broadcast-seeding rye into corn—Cereal rye is broadcast-planted into standing corn from late August to the first half of September, or when corn starts to open up the canopy (R5, dent stage, to R6, physiological maturity). Usually an airplane or high-clearance seeder is used for broadcast seeding. Planting when rain is in the forecast is ideal for good early growth and establishment.
  • Planting after corn harvest—In addition to broadcast-seeding, some producers in South Dakota also choose to drill cereal rye immediately after corn harvest (silage and/or grain). Drilling allows for better seed-to-soil contact, resulting in a uniform stand. Although fall plant growth can be somewhat limited after grain harvest, the stand in the spring is more uniform when compared to broadcast-seeding. Biomass for both seeding types are comparable when broadcast-seeded fields receive precipitation immediately after seeding. In other cases, rye in drill-seeded fields can yield up to 30% more biomass in the spring.
  • Seeding rate—For ground cover, 40 lbs./acre (bulk seeding rate) is a suggested in South Dakota. A higher seeding rate in the range of 60–70 lbs./acre can be used for weed suppression.
  • Tillage—Soybeans are usually no-till planted into growing rye in the spring, which is a green planting. Tillage can take away any benefit a cover crop has provided to the health of the soil. Cover crops and no-till usually go hand-in-hand.
Figure 1: This photo shows cover crop growth in mid-September in Lake County, SD. This field was seeded after cereal rye was hayed in June (David Karki)
Spring Work
  • Soil moisture—Cereal rye growth in the spring is usually good even when the previous fall was dry. If the winter and spring are dry and the spring weather forecast does not call for potential precipitation, spraying the rye by late April or early May is required. In South Dakota, rye grows rapidly in May and can use up already depleted soil moisture. In conditions with good soil moisture, rye can be allowed to grow until normal soybean planting time.
  • Termination timing—When soil moisture is adequate, the effects of termination timing of cereal rye on soybean yields has been minimal. Lower yields on soybean have usually been associated with lower soil moisture rather than termination timing. Soybean is usually planted into green rye, with the rye terminated by chemical spray at the time of soybean planting. Details on cover crop termination can be found in NRCS Cover Crop Termination Guidelines: Non-Irrigated Cropland (see Resources).
  • Herbicides—A full rate of glyphosate is the most common method used to terminate rye in the spring. Herbicide efficacy improves if sprayed when rye is actively growing and on a warm sunny day (>60°F). When sprayed well ahead of planting soybean, a broadleaf herbicide such as 2,4-D can also be tank-mixed as a general burndown mix.
  • Soybean planting—It is best to no-till plant soybean into either green rye (terminated at the time of planting) or dead residue (terminated about 10 days prior to planting). Check planting depth and seed furrow closure shortly after beginning in case any planter adjustments are needed. Although not suggested in South Dakota, if corn needs to be planted on fields with rye cover crop due to unusual circumstances, it is best to terminate rye at least 14 days prior to planting corn.
Figure 2: This photo shows rye cover crop growth in late April near Garretson, SD. This rye was aerial seeded the previous fall at corn physiological maturity (Anthony Bly)
Resources

Cover Crop Selector Tool—available from the Midwest Cover Crops Council, www.midwestcovercrops.org

Thinking Cover Crops? Winter Rye Between Corn and Soybean (South Dakota State University Extension website)

Management Implications of a Rye Cover Crop on Nutrient Cycling and Soybean Production in Southeast South Dakota: Focus on Rye Seeding Rates and Termination Timing (South Dakota State University thesis)

NRCS Cover Crop Termination Guidelines: Non-Irrigated Cropland (USDA-NRCS)

Author

David Karki, South Dakota State University Extension

(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

Eric Barsness, USDA-NRCS; Anthony Bly, South Dakota State University Extension; Eileen Kladivko, Purdue University; Anna Morrow, Midwest Cover Crops Council

The Midwest Cover Crops Council (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.

December 2022

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. ©2022 by MCCC. All rights reserved.

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The Midwest Cover Crop Council was first organized in 2006. Since its inception the organization has grown into a community that facilitates the sharing of cover crop knowledge within the Midwest and beyond.

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