Nitrogen Recommendations in North Carolina: Evaluation of Adapt-N.

As awareness of the environmental and economic cost of excess nitrogen (N) applications in agriculture increases, the need for producers to be able to confidently make precise N management decisions is critical. Adapt-N, a nitrogen recommendation tool, is designed to recommend N application rates in corn at or after V-6 and quantify the fate of N in corn fields including mineralization and leaching. However, its use has been mainly in the Northeast and Midwest. Soils and climate data from North Carolina have recently been incorporated into Adapt-N but the tool has not been validated against field conditions (e.g. soil, management, crop, yield goals, and weather parameters) in the Southeast. Two different trial types will be included: 1) N rate strip trials (farmer N rate, +/- 25%, and Adapt-N rate) in the lower Coastal Plain of North Carolina, and 2) three N response trials (Coastal Plain, Piedmont and Mountains). Corn yield data are evaluated with linear-plateau, quadratic, and quadratic plateau models to determine agronomic optimum N rates (AONR) and economic optimum N rates (EONR) for 26 corn trials over 2 years. These rates are then compared to N rate recommendations based on Adapt-N, the North Carolina Realistic Yield Expectation (RYE) database recommendations, and farmer rates. Year one data will be presented.