Dialing in the Most Corn-Profitable and Environmentally Responsible Nitrogen Rate

Fabian Fernandez

Corn production is an important activity for Minnesota’s economy and the livelihood of many Minnesotans. Corn requires substantial amount of nitrogen to optimize its productivity. However, nitrogen is expensive and farmers cannot afford over application because it affect their bottom-line and unused nitrogen degrades environmental quality. While many studies have focused on determining the economic optimum nitrogen rate (EONR) for corn production, relatively little has been done to determine the environmental impact of nitrogen rates at, above, and below the EONR. Partially for this reason, environmental groups arguing that the only consideration in nitrogen rate guidelines is economic return with no thought for the environment often confront university researchers and farmers. Research that takes a hard look at the intersection of profitable corn production and the various nitrogen loss pathways to the environment is needed to determine what that optimum nitrogen rate is. Having this information will allow more informed discussions and decisions to determine where the compromise should be and what compensation or allowances, if any, should be made in order to obtain the greatest overall economical, societal, and environmental benefits. This study aims at bridging this gap in knowledge. The study will use the common approach to calculate EONRs by establishing several nitrogen rates from zero to well above where a corn response is expected. However, in addition to corn-yield response curves, there will be integration of a comprehensive measurement of response curves for nitrogen loss pathways (nitrate leaching, nitrous oxide emissions, and ammonia volatilization).