Cereal Rye in Continuous Corn with Fall Fertilizer N Application.

Our results demonstrate that cereal rye after corn has great potential to take up soil nitrate, thereby decreasing nitrate concentrations and loads in tile drainage water; however, can we grow cereal rye ahead of corn and get the same soil health and water quality benefits without jeopardizing corn yields? Cereal rye has been shown to negatively affect corn yields and a number of factors likely contribute such as N immobilization, allelopathy, soil moisture and temperature, and disease. Unfortunately, our results have shown that a radish and oat mixture following corn did not produce sufficient biomass or accumulate enough N to affect tile nitrate loss. Therefore, we believe that it is critical to develop a system’s approach to overcome the yield depression associated with cereal rye ahead of corn. The main objective of this study is to learn how to best manage cereal rye as a winter cover crop before corn in continuous corn. Our experimental design will accommodate three corn N fertilizer treatments: (1) 50% in the fall-25% at planting-25% side-dress; (2) 100% in the spring preplant; and (3) 25% at planting and 75% side-dress with and without cereal rye and also with three spring cover crop termination dates (approximately 2 weeks apart). This approach will allow us to investigate N release from the cover crop under various N fertilizer regimes and to evaluate N immobilization vs. allelopathy in regard to negative cover crop effects on the subsequent corn crop. In addition, soil sampling and early season corn growth measurements will provide evidence as to what soil N pool was accessed by cereal rye. We hope this study can identify the combination of management practices that generates sufficient cereal rye growth to attain the numerous benefits and ecosystem services provided by the cover crop and still produce maximum corn yield.