Nitrogen is essential for growth and reproduction of crops and is involved in many important plant biochemical processes. Nitrogen management is critical for optimal yields for corn production systems. This publication discusses long-term research done in Iowa and shows corn yields average about 60 bu/acre for continuous corn and 115 bu/acre for corn following soybean when corn is not fertilized. However, corn fertilized with N will easily yield 200 bu/acre or more. This means soil management and nitrogen fertilization practices, such as using economical optimum N rates, should be used to help optimize crop yields, use N efficiently, and enhance water quality.

The regional Corn Nitrogen Rate Calculator website, which has been helping farmers determine profitable nitrogen rates since 2005, can be found at: cnrc.agron.iastate.edu. This tool provides a process to calculate economic return to N application with different nitrogen and corn prices and to find profitable N rates directly from recent N rate research data. Using the Maximum Return to Nitrogen concept within the calculator helps farmers implement the most economical nitrogen rate inputs, which helps moderate water quality issues.