Traditionally in the northern Corn Belt crop rotations consist of corn/soybean with little if any small grains included. This short two-year rotation has resulted in significant problems with various pests (weeds, insects and disease). A field experiment located near Brookings, SD on a Barnes clay loam (fine-loamy, mixed, superactive, frigid Calcic Hapludolls) was established in the fall of 2000 to evaluate the impact of diversified four-year crop rotations on crop yield and quality. The experimental design was a randomized complete block with four replications. Eight four-year rotations were evaluated with crops including corn, soybean, winter wheat, spring wheat, oat, dry pea, canola, and sunflower. Plots were set-up such that each phase of the rotation was present each year. A corn/soybean rotation was also included for comparison purposes. Rotation effects will be evaluated by comparing the corn phase of each rotation. Analysis will be performed on grain yield, quality and in season crop phenology. Initial results show that there was a significant difference in corn yield when compared between the different rotations. Corn yield following dry peas resulted in the highest yield (>8,000 kg ha-1), while corn following corn in a four-year rotation with spring wheat and soybean had yield lowest yields (<3,500 kg ha-1). The traditional two-year rotation of corn/soybean resulted in grain yield was just under 7,000 kg ha-1. Initial grain yield data shows that corn only once in four years results in higher yields compared to corn grown every other year or grown in a shorter rotation.