Objective of this project wasto study corn nitrogen (N) fertilization requirement and corn/soybean yield response when grown in a rye cover cropping system. Multiple rates of N fertilizer were applied, with measurement of corn yield response to applied N and soybean yield with and without a fall-planted winter rye cover crop. The study was conducted at multiple research farms, with the intent for comparison of with and without a cover crop system across varying soil and climatic conditionsin Iowa.