Winter cereal rye continues to be promoted as a viable cover crop within Iowa for corn and soybean production systems. Several environmental benefits accrue with use of cover crops, including reduction of nitrate in drainage water, soil erosion control, and reduced phosphorus (P) runoff loss. In the Iowa Nutrient Reduction Strategy, a rye cover crop is estimated to reduce nitrate-N concentration by 31%, a sizeable impact. However, questions remain about rye cover crop effects on corn nitrogen (N) fertilization requirement, N supply from the cover crop, and crop yield. To help answer these questions, a series of studies were conducted to evaluate corn economic optimum N rate (EONR), rye cover crop degradation and N recycling following termination, rye shoot and root biomass and nutrient composition, corn and soybean yield, and agronomic practices to improve corn yield in a rye cover crop system.