McNay Research and Demonstration Farm
This project is designed to study the N fertilization needs of continuous corn (C-C) and corn rotated with soybeans (C-S) as influenced by location and climate. Multiple rates of fertilizer N are spring applied, with the intent to measure yield response to N within each rotation on a yearly basis for multiple years at multiple sites across Iowa. This will help determine N requirements for each rotational practice, differences that exist between the two rotations, and responses to applied N across different soils and different climatic conditions. It will also allow for the evaluation of tools used to adjust N application.
Iowa State University
Sawyer, John E. and Barker, Daniel W., "Seasonal and Rotational Influences on Corn Nitrogen Requirements" (2003). Iowa State Research Farm Progress Reports. 1462.