Henry J Mascagni Jr., LSU Agricultural Center - Northeast Research Station, St. Joseph, LA and Brenda Tubana, School of Plant, Environmental, and Soil Sciences, LSU AgCenter, Baton Rouge, LA
Nitrogen (N) fertilization is a critical cultural practice required for producing maximum corn yield and profitability. Calibrating yield response to N rate is an evolving process for better defining the economic optimum N rate (EONR). This not only enhances profitability but also, at the same time, minimizes environmental risks associated with excess nitrate-N. Field N-calibration studies were conducted for the last ten years at the Northeast Research Station on Commerce silt loam and Sharkey clay. Nine trials were conducted on Commerce silt loam and 17 trials (5 low-yield potential and 12 high-yield potential) on Sharkey clay. Nitrogen was knifed in as 32-0-0 or 30-0-0-2 N solutions at about the 2-leaf growth stage. On Commerce silt loam, maximum corn yield occurred at 220 lb N/acre and EONR was 190 lb N/acre. On Sharkey clay, maximum yield occurred at 250 lb N/acre and EONR was 220 lb N/acre in both the low-yield and high-yield categories.