Using Corn as a Cover Crop

By:  Peter Thomison, Ben Brown, Sam Custer, Greg LaBarge, CPAg/CCA, Sarah Noggle, Mark Sulc, Eric Richer, CCA, Harold Watters, CPAg/CCA

Based on information from across the Corn Belt, including states where they have more experience with delayed planting of corn (University of Wisconsin – http://wisccorn.blogspot.com/2019/06/B102.html) and Iowa State University – https://crops.extension.iastate.edu/cropnews/2019/05/cover-crop-options-prevented-planting-fields), these are our best recommendations for using corn as a cover crop.

Although the yield potential of corn planted in July for grain and silage is very low, corn makes an excellent “emergency” forage when planted in July. Moreover, unlike some other forage crops, Ohio producers know how to grow it. We also are aware of limited seed supply for several alternatives that typically could be used. Farmers should consult with their insurance agent to see if harvesting as forage will affect any current or future insurance payments on prevented plant acres.

As a cover crop, corn can establish a canopy rapidly. It has a deep root system that is highly effective in scavenging nutrients. Even when planted as late as July, it can produce a significant residue.

To optimize the use of corn as a cover crop, consider the following agronomic practices.

1. It is illegal to use seed or grain with transgenic hybrid (bioengineered or GMO) to plant a corn cover crop. For more specifics, see https://www.agcelerate.com/Home (URL verified 6-25-2019).
2. Plant corn at a higher seeding rate than normal: 40,000 seeds per acre or greater and in narrow rows (22-inch row spacing or less). This will promote canopy closure and result in better erosion and weed control (OSU Agronomy Guide, 15th edition –  https://stepupsoy.osu.edu/sites/hcs-soy/files/Ohio%20Agronomy%20Guide_11APR18.pdf URL verified 6-25-2019).
3. Corn may be the only choice for a cover crop depending on herbicide applications earlier in the year.
4. If corn planted in July as a cover crop produces seed, grain produced must not be harvested.
5. Corn seeded as a cover crop on Prevented Planting acres may be hayed, grazed, or chopped on or after September 1 for 2019 – https://www.rma.usda.gov/News-Room/Press/Press-Releases/2019-News/RMA-Announces-Change-to-Haying-and-Grazing-Date (URL verified 6-25-2019).
6. Before grazing, check the herbicide label to ensure there are no restrictions on feeding forage to livestock.
7. Reduce tillage as much as possible (no-tillage preferable) to ensure soil moisture necessary for germination and to reduce erosion potential while the cover crop develops.