The yield of crops can be significantly affected by the crop rotation. Crop characteristics and associated management practices influence physical and chemical properties of soil; water availability; and incidence of diseases, weeds, and pests. Including legumes in a rotation usually increases soil nitrogen (N) availability for grain crops. A crop rotation was started in 1984 to study the effect on crop yields of seven crop sequences and N fertilization rates for corn. Table 1 shows the sequences and N rates used since 1984. Nitrogen treatments of 0, 80, 160, and 240 lb N/acre were applied only for corn. Granulated urea was incorporated into the soil by plowing or field cultivating in the spring or fall for continuous corn and in the spring for other rotations. Oats were always undersown with alfalfa. No hay was harvested after harvesting oats, but three harvests were made in other years. Hay yields for rotation 5 (one year) and rotation 6 (two years) are not shown.