Oat and rye overseeded into soybean as fall cover crops in the Upper Midwest

Oat, rye, and an oat-rye mixture were overseeded into soybean in August to determine the shoot dry matter and residue cover produced by these cover crops and their effect on subsequent soybean and corn yield. The oat cover crop reduced soybean yield in only one year and the other cover crops had no effect. Fall cover crop shoot dry matter averaged 440 kg ha^-1 and did not differ among the three cover crops. Rye shoot dry matter measured in the spring averaged 1660 kg ha^-1 for the rye and oat-rye mixture. Cover crops increased surface residue cover by 7 to 18% in some years. Corn yields were reduced following rye and oat-rye cover crops, but were not reduced by the oat cover crop. Oat overseeded into soybean is a viable cover crop system in Iowa and unlike rye, does not reduce yield of the following corn crop.