Cover crops can be successfully incorporated into various corn rotation systems. The KBS/MSUE cover crop program, through grants from the Michigan Department of Agriculture Groundwater Stewardship program has researched cultivars, timing and economics for seeding cover crops in corn.
CULTIVARS AND TIMING
Cover crops can be seeded into corn at any of three different corn growth stages. A on the chart represents overseeding when the corn is at stage V-4 to V-8 immediately before or after your last cultivation. The cultivars we have had the most success with are crimson clover, mammoth red clover, medium red clover, red/sweet clover mix and annual ryegrass.
B on the chart represents a seeding that requires special equipment, such as a highboy or an airplane. This seeding is most successful when the corn crop just begins drying down. At this time, sunlight begins breaking through the canopy, allowing cover crop growth. The cultivars that have been most successful for seeding at this time are oilseed radish, oats, rape/turnip, crimson clover, hairy vetch and red/sweet clover mix. Cereal rye can be seeded into standing corn successfully from mid to late August.
Another window for seeding cover crops into corn occurs when the corn plants are drying down and/or harvested for silage (see C on the chart). For shelled corn, use highboy or aerial seeding. Silage corn fields can be seeded with a bulk spreader followed by shallow tillage. The cover crops that have worked best at this corn stage are cereal rye, wheat* and triticale.
The KBS/MSUE cover crop program has created an economical method for overseeding cover crops into corn. This system includes a ten-inch banded herbicide treatment followed by one or two cultivations. The 67 percent cost savings from the herbicide allows farmers to purchase cover crop seeds. To cut costs on cover crop seed, place the seed in a 20-inch band between the corn rows, thus reducing cover crop seed by 33 percent. This system only works with the early overseeding practice (letter A on the chart).
Researchers' success incorporating cover crops into corn can be directly correlated to environmental conditions. Adequate moisture and light are critical in establishing cover crops. The KBS/MSUE project team continues research on manipulating corn systems to provide a better habitat for cover crops. These projects include: determining the best corn plant population, corn hybrid characteristics and development, and cover crop tolerance to herbicides.
* After Hessian fly-free date.
Funding for this bulletin was provided by the Michigan Groundwater Stewardship Program.