Using Corn and Soybean as cover crops on Prevented Planted acres in Wisconsin during 2019

June 25, 2019
RE: Using Corn and Soybean as cover crops on Prevented Planted acres in Wisconsin
during 2019

To whom it may concern:
For a crop to be considered a cover crop RMA states that “For crop insurance purposes, a cover crop is a crop generally recognized by agricultural experts as agronomically sound for the area for erosion control or other purposes related to conservation or soil improvement.” Soybean and corn both meet this requirement. However please remember that BMP’s must be followed to meet this requirement. Every producer who  eclares Prevent Planting must get approval from his or her crop insurance agent before any Prevent Planting management plan is implemented.

Farmers taking the full prevented plant indemnity should note that they cannot ever harvest the cover crop for grain or seed. RMA rules allow, only after September 1, grazing and harvest as hay (for bedding or feed) and now for silage, haylage or baleage. If a farmer wants to harvest it as grain or seed, then they should declare it as an alternative crop and only collected the partial (35%) prevented plant indemnity.”

Briefly the goal of a cover crop is to protect the soil from erosion (wind and water), to improve water quality by capturing nutrients, to build organic matter, and to suppress weeds. Agronomic guidance regarding the use of corn and soybean as a cover crop include:

Seed: Conventional hybrids and open-pollinated varieties are less expensive than bioengineered hybrids. Neither seed nor grain from bio-engineered corn hybrids can be used as cover crop seed. Upon purchase of bio-engineered hybrids, farmers sign a contract that: 1) limits  usage of grain to specific end product channels, 2) restricts ownership of bio-engineered traits, and 3) requires a refuge (stewardship). There has been some discussion of using the F2 (grain) of 2018 production (“bin-run” seed/grain). A 10-20% grain yield drag would be expected for F2 seed, however, little grain yield is expected anyway with July planting dates. Using bin-run grain as seed might be possible for conventional hybrids and open-pollinated varieties. Check seed labels and grower agreements to make sure. Again, it is illegal to use bio-engineered hybrids. For specifics about contracts for bio-engineered hybrids, see

Performing any ONE of the following practices, if different from the current on-farm commercial production practice, indicates that the objective of growing corn for grain has changed to to the objective of growing corn as a cover crop.

Plant population and seed costs: Higher populations lead to faster ground cover and helps with weed suppression. Minimum populations upwards of 35,000 plants/A are needed for corn grown as a cover crop. However, seed costs can be prohibitive for higher populations.

Narrow row spacing: Corn is a row crop. Using a narrower row corn planter (< 30-inches), twin-row planter, or a grain drill can lead to faster ground cover by the corn canopy and weed suppression. Criss-crossed rows can lead to quicker canopy cover.

Crop rotation: Rotating crops helps with interrupting pest cycles and promotes early growth and quicker canopy coverage. The choice of the cover crop this year should be based upon the subsequent crop intended next year. For example, if soybean is planned for the field next year then corn (or some grass crop) should be the cover crop this year. Planting into residue: Seeding into fields with > 30% residue provides some ground cover between planting and canopy establishment.

Pesticides: Herbicides should be used to help with weed control. Use care about pre-grazing and/or pre-harvest restrictions after September 1.

Nitrogen: The most important nitrogen applied to corn is the first 40 to 60 lb N/A. Even this may not be needed if N credits can be taken. Reducing N rate would improve cost of production, especially since little grain is expected.

July plantings rarely result in corn grain production in Wisconsin. A killing frost usually occurs
during September or early October. If grain is produced and kernels develop beyond the milk to
dough (R3-R4) stage then the crop should be cut with a haybine.

In a late planted, soybean cover crop situation, plant a minimum of 150,000 seeds per acre and
strive to plant in narrow row spacings (<30 inches). This recommendation is intended to
minimize soil erosion, maximize ground cover and weed suppression as well as provide
adequate N fixation. I do however understand if a farm operation is limited by equipment
restrictions (e.g. they only have a 30 inch row planter) I would not preclude them from being
eligible to plant soybean as a cover crop. The next consideration is cost. Normally the cost of
soybean seed to be used as a cover crop on a per acre basis would be cost prohibitive; however
since soybean seed is usually not saved from year to year and treated seed is often devitalized it
is often offered at a deep discount late in the year so shop around. Frankly with only 60% of the
WI crop planted there should be some reasonably priced seed to be used as cover crops.

Joseph G. Lauer
Professor & Extension Corn Specialist
Department of Agronomy
University of Wisconsin, Madison
1575 Linden Drive
Madison, WI 53706
Phone: 608-263-7438
Shawn P. Conley
Professor & Soybean/Wheat Extension Specialist
Department of Agronomy
University of Wisconsin, Madison
1575 Linden Drive
Madison, WI 53706
Phone: 608-800-7056


2019_06 – RMA Letter – Corn Soybean As Cover Crop (PDF, 1PG).

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