Nitrogen Rate Recalibration in North Dakota.

Historical data from 1970 through 2004 that examined the nitrogen response of spring wheat and durum were added to a database of recent N rate studies from 2005-2008 in order to update N recommendations to wheat in North Dakota. Yield and protein response to N rates, combined with residual fall soil nitrate to 60-cm and consideration of the N contribution by previous crop were compared in both a state-wide basis, and by agri-climatology region. The responses were subjected to economic scrutiny by imposing costs for N fertilizer together with possible wheat prices to graph the economic response to N. These economic response curves were different by region. In addition, the contribution of soil organic matter is being considered. New N recommendations for wheat will vary by region within the state and may include a credit or deficit organic matter consideration.