Crop rotation influences yield and various soil properties due to changes in availability of nutrients and water, physical properties, and incidence of pests and weeds. A rotation crop study was started in 1979 to assess the effects of various crop sequences and nitrogen (N) fertilization for corn on crop yield. The rotations are continuous corn for grain and for silage, continuous soybean,several corn-soybean sequences with one to three corn crops for every soybean crop, and corn-corn-oats/alfalfa. Alfalfa is undersown with oats and only oats grain is harvested the first year.