Cover Crops Interseeded into Corn and Soybeans: Performance and Cash Crop Yield.

To reduce the costs associated with seeding a cover crop farmers want to know how a cover crop interseeded within 45 days of corn or soybean planting will affect cash crop yield. Six peer reviewed scientific studies from 1984 to 2008 evaluated crop yield with or without a cover crop interseeded within 45 days after planting. Studies were conducted in Minnesota, Michigan, New York, Brazil, Ontario and Quebec. Across these six studies, 48 comparisons were made of corn yields, six comparisons were made of corn silage yield, and 58 were made of soybean yields. Cover crops evaluated included AC greenfix, alfalfa, Austrian winter pea, barrel medic, berseem clover, black medic, brachiaria (signalgrass), cereal rye, creeping red fescue, crimson clover, Dutch white clover, fenugreek, hairy vetch, perennial ryegrass, Persian clover, pigeon pea, red clover, red clover + ryegrass, ryegrass, strawberry clover, subterranean clover, wheat, white clover + ryegrass and yellow sweetclover. In corn, cover crops interseeded near V6 had no effect on yield 71% of the time. In silage, cover crops interseeded near V6 had no effect on yield. In soybeans, cover crops seeded within 45 days after planting resulted in no difference in yield 84% of the time. In six of these instances, cover crop growth reached high enough into the soybean canopy to stain the soybeans harvested, thus potentially reducing the marketability of the bean. Results from these six studies are chosen because of the large number of cover crops they tested suggest that interseeding a cover crop into corn, corn silage or soybean cash crops is unlikely to reduce crop yield.