Iowa

Midwest Cover Crops Council (MCCC-121)

Iowa State University Extension (CROP 3165)


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 for planting a cover crop after corn silage harvest and then planting corn for grain or silage as the next crop. The early harvest of corn silage provides an extended planting window for establishing a cereal rye cover crop.

Planning and Preparation
  • Planning—Read about cover crops. Go to field days. Start small. Be timely. Prioritize management based on purpose and objectives. Arrange for equipment, custom operators, or additional labor as needed.
  • Corn hybrid and planting—If possible, plant the preceding corn silage crop early, and use a hybrid within the adapted maturity range for your location.
  • Residual corn herbicides—Cereal rye can be planted in the fall and produce a successful stand following most spring-applied residual corn herbicides. If cereal rye is to be grazed or harvested for forage, there are some time-interval restrictions. (See Herbicide Use May Restrict Grazing Options for Cover Crops -Resources.)
  • Seed purchase—Pre-order cereal rye seed in early summer. Named rye varieties can produce substantially more growth and have predictable development, but they are usually more expensive than variety not stated (VNS) seed. Use good quality seed that has been cleaned, tested for germination and weed seed contamination, and purchased from a reputable seed dealer.
Fall Work
  • Corn silage harvest—Prioritize harvest of fields where cereal rye is to be planted.
  • Tillage or no-tillage—Generally, it is easier to integrate cover crops into no-till or strip-till systems. If tillage is necessary to incorporate manure, fertilizer, or lime, or to smooth the seed bed after corn silage harvest, it should take place prior to rye seeding.
  • Timing of planting—Ideally, plant cereal rye as soon as possible after silage harvest. Plant no later than the following dates: October 21 in northern Iowa, October 28 in central Iowa, and November 7 in southern Iowa.
  • Seeding rate—Use 55 lbs./acre for drilled seed and 60 lbs./acre for shallow incorporation. Seed should have a germination rate greater than 85%.
  • Planting method—Drill to a depth of 0.75–1.50 inches or broadcast with shallow incorporation to 1.50 inches.
  • Manure, P, K, or lime—For best rye establishment, any manure, P, K, or lime should be injected, subsurface banded, or surface applied and incorporated before planting the cover crop. Manure can also be injected with a low-disturbance applicator after the rye cover crop is at least 4 inches tall, but significant damage to the cover crop may occur. Surface-applying granular P, K, or lime before the ground completely freezes can be done with minimal cover crop damage if the soil is not too wet.
Figure 1: This cereal rye cover crop, shown here in early April, was planted the previous fall following corn silage in northeast Iowa. (Tom Kaspar)
Figure 1: This cereal rye cover crop, shown here in early April, was planted the previous fall following corn silage in northeast Iowa. (Tom Kaspar)
Spring Work
  • Termination timing—Terminate the cereal rye in spring when plants are 6 to 12 inches tall and actively growing or at least 10 days before planting corn—whichever comes first. Check current crop insurance rules regarding timing of termination of cover crops. (See NRCS Cover Crop Termination Guidelines -Resources.)
  • Termination herbicide—Cereal rye can typically be terminated with a full rate of glyphosate (1 lb. acid equivalent/acre) after the rye begins growing in the spring. Use best management practices for glyphosate to improve effectiveness. Glyphosate will kill rye more quickly if the rye is rapidly growing and temperatures are greater than 55°F during the day and greater than 40°F at night. Rye sprayed during cooler weather can be more difficult to kill, may require higher glyphosate rates, or will die more slowly.
  • Termination modifications for wet weather—In a wet or windy spring, be ready to take advantage of any break in the weather and/or use low axle weight sprayers.
  • Option to harvest cereal rye as a silage crop—A rye cover crop planted in the fall and harvested at boot stage can provide a substantial amount of good quality forage. However, waiting for cereal rye to reach the boot stage (mid-May to early June) will delay planting of the next corn crop and may decrease its yield. If the following corn crop will be insured, then rye should be terminated and corn planted before the crop insurance late-planting deadline. (See Resources.)
  • Corn planting—Almost all modern row planters are fully capable of planting corn into a dead cereal rye cover crop. Row cleaner attachments can sometimes be beneficial to increase soil warming, but setting them too deep can cause problems. Planter adjustments are usually needed to ensure correct planting depth and seed furrow closure.
  • Starter fertilizer—Consider equipping your corn planter with a 2×2 starter fertilizer applicator and aim for a starter fertilizer rate between 30–50 pounds of actual N per acre.
  • Scouting after planting—Scout for corn emergence, population, and insect pests. Additionally, scout for weeds because substantial cereal rye residue can often delay emergence of annual weeds, which may then delay the application of post-emergence herbicides.
Resources

Cover Crop Selector Tool —available from Midwest Cover Crops Council

Effect of residual herbicides on cover crop establishment (Iowa State Extension and Outreach Integrated Crop Management Encyclopedia Article)

Herbicide Use May Restrict Grazing Options for Cover Crops (Iowa State Extension and Outreach publication CROP 3082, revised January 2017)

NRCS Cover Crop Termination Guidelines (version 4, June 2019)—available from the USDA Natural Resources Conservation Service

Planting Winter Rye after Corn Silage: Managing for Forage, J. Stute, K. Shelley, D. Mueller, and T. Wood. 2009.

Cover Crop Management (Iowa Agronomy Technical Note 38)—available from the USDA Natural Resources Conservation Service

Post Soybean, Going to Corn: Use Oats (Iowa Cover Crop Recipe series, MCCC-104)

Post Corn, Going to Soybean: Use Cereal Rye (Iowa Cover Crop Recipe series, MCCC-103)

Authors

Tom Kaspar, USDA-ARS (retired); and Mark Licht, Iowa State University (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

Stefan Gailans, Practical Farmers of Iowa; Michael Henderson and Kevin Kuhn, USDA-NRCS; Eileen Kladivko, Purdue University; Keith Kohler, USDA-ARS; Anna Morrow, Midwest Cover Crops Council; and Matt Ruark, Kevin Shelley, and Dan Smith, University of Wisconsin-Madison

Acknowledgments

This publication was developed with contributions and collaboration from Iowa Learning Farms and Practical Farmers of Iowa.

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 2020

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. ©2020 by MCCC. All rights reserved.

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Midwest Cover Crops Council (MCCC-104)

Iowa State University Extension (CROP 3159)


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 soybean-corn rotation. Often the easiest place to begin is to plant a cover crop ahead of a soybean cash crop following corn, so consider starting with the companion recipe titled Post Corn, Going to Soybean: Use Cereal Rye (publication MCCC-103; see Resources).

Planning and Preparation
  • Planning—Read about cover crops. Go to field days. Start small. Be timely. Prioritize management based on purpose and objectives.
  • Soybean cultivar and planting—If possible, plant preceding soybean crop early and use an early-maturity-group cultivar. Some possible strategies are to try cover crops in a field that is usually harvested first, on sloping ground, or where you plan to plant your earliest-maturity-group soybean cultivar.
  • Residual soybean herbicides—Oats can be planted in the fall and produce a successful stand following spring application of most residual soybean herbicides. If the oats are grazed, there are some time-interval restrictions. (See Resources.)
  • Seed purchase—Order oat seed early, usually by early August. Named oat varieties can produce substantially more growth, but they are usually more expensive than VNS (variety not stated) seed. Use good quality seed that has been cleaned, tested for germination and weed seed contamination, and purchased from a reputable seed dealer.
Fall Work
  • Soybean harvest—Harvest fields where oats are to be planted as early as possible. This is not as critical if cover crops are seeded before harvest.
  • Tillage or no-tillage—Generally, it is easier to integrate cover crops into no-till or strip-till systems. If full-width tillage is planned, it should be delayed until after the oats are killed by freezing in late fall to allow time for oat cover crop growth. Usually it is more desirable to delay tillage until spring to maintain surface cover and prevent erosion.
  • Timing of planting—Oats are relatively frost tolerant but are not winter hardy. In general, oats will grow well in the fall if they are planted at least six weeks before the average hard frost date (28ºF). To allow for adequate growth, in northern Iowa this should be before September 9; in central Iowa, before September 16; and in southern Iowa, before September 23. (See Cover Crop Management publication in Resources.)
  • Seeding rate—Minimum seeding rate: 60 lbs./acre. Beginners should consider higher seeding rates for broadcast seeding methods with or without incorporation. Note that these rates assume the seed will have germination rates greater than 85%.
  • Planting method—Aerial seed with a plane or helicopter or broadcast/drop seed with a ground-based vehicle into the standing soybean crop. In most of Iowa, aerial or broadcast seeding should take place in late August and/or just before soybean leaves begin to yellow. Rainfall after seeding is essential for establishment, but normal average weekly rainfall totals in Iowa decrease as fall progresses, so in most years, it is usually better to seed late in August rather than wait for leaf yellowing.
  • Alternative planting method—Drill to a depth of 0.75–1.50 inches or broadcast with shallow incorporation to less than 1.50 inches immediately after soybean harvest but before recommended dates above. For this method, the seeding rate is also 60 lbs./acre.
  • Scouting—In the fall, scout your oat cover crop to determine how well it is growing and its coverage.
  • Fertility or liming—Surface applying P, K, or lime before the ground freezes can be done without harming the cover crop too much if the soil is not too wet, although some damage will occur in the wheel tracks. If P, K, or N fertilizer, or manure is injected in the fall, it is usually best to wait until after the cover crop has winter-killed. In this case, use a low-disturbance applicator to minimize incorporation of surface residues.
Figure 1: Dead oat cover crop residue in the spring after oats and some radishes were drilled following an early soybean harvest in Indiana (Eileen Kladivko)
Figure 1: Dead oat cover crop residue in the spring after oats and some radishes were drilled following an early soybean harvest in Indiana (Eileen Kladivko)
Spring Work
  • Scouting before planting—In the spring, scouting relative to the cover crop is usually not needed because it has winter-killed.
  • Termination—Unlike overwintering cover crops, oats winter-kill, so termination is not needed.
  • Corn planting—Almost all modern row planters are fully capable of planting corn into a dead oat cover crop and soybean residues without preplant tillage. Row cleaner attachments can sometimes be beneficial to increase soil warming. As usual, check planting depth and seed furrow closure shortly after beginning to plant because some adjustments may be needed with higher residue levels.
  • Starter fertilizer—If N fertilizer has not been applied before planting, consider equipping your corn planter with a 2×2 starter fertilizer applicator and aim for a starter fertilizer rate between 30–50 pounds of actual N per acre.
  • Scouting after planting—As usual, scout for corn emergence, population, and insect pests after planting. Additionally, scout for weeds because substantial oat and soybean residue may delay emergence of annual weeds, which may then delay the application of post-emergence herbicides.
Resources

Cover Crop Selector Tool — available from the Midwest Cover Crops Council

Cover Crop Management (Iowa Agronomy Technical Note 38)—available from the USDA Natural Resources Conservation Service

Effect of residual herbicides on cover crop establishment (Iowa State Extension and Outreach Integrated Crop Management Encyclopedia Article)

Post Corn, Going to Soybean: Use Cereal Rye (Iowa Cover Crop Recipe series, MCCC-103)—available from the Midwest Cover Crops Council

Authors

Tom Kaspar, USDA-ARS (retired); Mark Licht, Iowa State University (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

Shalamar Armstrong, Purdue University; Marisol Berti, North Dakota State University; Eileen Kladivko, Purdue University; Keith Kohler, USDA-ARS; Anna Morrow, Midwest Cover Crops Council; DeAnn Presley, Kansas State University; Vaughn Sothman, Sharp Brothers Seed Co., Kansas; and Anne Verhallen, Ontario Ministry of Food and Agriculture

Acknowledgments

This publication was developed with contributions and collaboration from Iowa Learning Farms and Practical Farmers of Iowa.

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.

Revised May 2019

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. ©2019 by MCCC. All rights reserved.

Share

Midwest Cover Crops Council (MCCC-103)

Iowa State University Extension (CROP 3158)


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 corn-soybean rotation. Planting a cover crop ahead of a soybean cash crop is often the easiest way to introduce cover crops into your rotation.

Planning and Preparation
  • Planning—Read about cover crops. Go to field days. Start small. Be timely. Prioritize management based on purpose and objectives.
  • Corn hybrid and planting—If possible, plant preceding corn crop early and use an early maturity hybrid. Possible strategies are to use cover crops in a field that is usually harvested first, on sloping ground, or where you plan to plant your earliest maturity hybrid, corn silage, or seed corn.
  • Residual corn herbicides—Cereal rye can be planted in the fall and produce a successful stand following most spring-applied residual corn herbicides. If cereal rye is grazed or harvested for forage, there are some time-interval restrictions. (See Resources.)
  • Seed purchase—Order cereal rye seed early, usually by early August. Named rye varieties can produce substantially more growth and have predictable development, but they are usually more expensive than VNS (variety not stated) seed. Use good quality seed that has been cleaned, tested for germination and weed seed contamination, and purchased from a reputable seed dealer.
Fall Work
  • Corn harvest—Harvest fields where cereal rye is to be planted as early as possible.
  • Tillage or no-tillage—Generally, it is easier to integrate cover crops into no-till or strip-till systems. If full-width tillage is planned, do it immediately after corn harvest or delay it until after the planned cover crop termination date in the spring to allow time for cover crop growth.
  • Timing of planting—Ideally, plant cereal rye as soon as possible after corn harvest and before two weeks after the average hard frost date (28˚F). In northern Iowa, this would roughly be before October 21; in central Iowa, before October 28; and in southern Iowa, before November 7. (See Cover Crop Management publication in Resources).
  • Seeding rate—Minimum seeding rate: 45 lbs./acre. Beginners should consider 55 lbs./acre for drilled seed and 61 lbs./acre for shallow incorporation. Note that these rates assume the seed will have germination rates greater than 85%.
  • Planting method—Drill to a depth of 0.75–1.50 inches or broadcast with shallow incorporation to less than 1.50 inches.
Figure 1: Cereal rye cover crop planted following corn in late April on the Steve Berger farm in Iowa (Tom Kaspar)
Figure 1: Cereal rye cover crop planted following corn in late April on the Steve Berger farm in Iowa (Tom Kaspar)
Spring Work
  • Scouting before planting—In the spring, scout your cereal rye cover crop to determine how well it is growing and its coverage. If rainfall is below normal, then scout to monitor soil moisture in case earlier cover crop termination is needed.
  • Termination timing—Terminate the cereal rye in spring when the plants are 6 to 12 inches tall and actively growing or more than 10 days before planting soybean—whichever comes first. Many experienced cover crop users will successfully terminate cereal rye much taller than 12 inches or less than 10 days before planting, but termination and planting may be more difficult for new users.
  • Termination herbicide—Cereal rye can easily be terminated with a full rate of glyphosate (1 lb. acid equivalent/acre) after the rye begins growing in the spring. Effectiveness and rapidity of termination improves if rye is rapidly growing and air temperatures are warmer (> 60˚F). Larger rye, rye past the boot stage, or rye sprayed during cooler weather can be more difficult to kill, may require higher glyphosate rates, or will die more slowly. Use best management practices for glyphosate to improve effectiveness.
  • Termination modifications for wet weather—In a wet or windy spring, when it has been very difficult to get into the fields to spray, be ready to take advantage of any break in the weather and/or use low axle weight sprayers. If projected soybean planting is less than 10 days away and the rye is tall, then it often works better to spray a day or two before planting. Crop insurance requires that cover crops be terminated at the very latest by five days after soybean planting in the southeastern two-thirds of Iowa and before soybean planting in the northwestern one-third of Iowa.
  • Soybean planting—It is usually easiest to no-till plant soybean into the dead, brown cereal rye cover crop. Almost all modern row planters and drills are fully capable of planting soybean into a dead cereal rye cover crop. If wet or windy weather has delayed cereal rye termination, it is usually better to plant into standing green plants rather than into large green plants that are dying and have fallen on the soil surface, forming a mat. For either scenario, check planting depth and seed furrow closure shortly after beginning to plant because some adjustments are usually needed.
  • Scouting after planting—Scout for soybean emergence, population, and insect pests. Additionally, scout for weeds because substantial cereal rye residue often can delay emergence of annual weeds, which may then delay the application of post-emergence herbicides.
Resources

Cover Crop Selector Tool  — available from the Midwest Cover Crops Council

Cover Crop Management (Iowa Agronomy Technical Note 38)—available from the USDA Natural Resources Conservation Service

Effect of residual herbicides on cover crop establishment (Iowa State Extension and Outreach Integrated Crop Management Encyclopedia Article)

NRCS Cover Crop Termination Guidelines: Non-Irrigated Cropland—available from the USDA Natural Resources Conservation Service

Post Soybean, Going to Corn: Use Oats (Iowa Cover Crop Recipe series, MCCC-104)—available from the Midwest Cover Crops Council

Authors

Tom Kaspar, USDA-ARS (retired); Mark Licht, Iowa State University (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

Shalamar Armstrong, Purdue University; Marisol Berti, North Dakota State University; Eileen Kladivko, Purdue University; Keith Kohler, USDA-ARS; Anna Morrow, Midwest Cover Crops Council; DeAnn Presley, Kansas State University; Vaughn Sothman, Sharp Brothers Seed Co., Kansas; and Anne Verhallen, Ontario Ministry of Food and Agriculture

Acknowledgments

This publication was developed with contributions and collaboration from Iowa Learning Farms and Practical Farmers of Iowa.

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.

Revised May 2019

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. ©2019 by MCCC. All rights reserved.

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