353-2 Using Maximum Yield Response to Nitrogen to Verify Corn Nitrogen Recommendations.
See more from this Division: ASA Section: Agronomic Production SystemsSee more from this Session: Adaptive Nutrient Management: I
Wednesday, November 5, 2014: 1:15 PM
Long Beach Convention Center, Room 101A
Nitrogen (N) rates recommended for corn production are rarely field verified for their accuracy partially due to the difficulty associated with in-field determination of actual corn N requirements. Measuring delta-yield, the maximum yield response associated with applying a non-limiting N fertilizer rate, offers the potential for a simplified verification of corn N fertilizer recommendations. A database of 600 Ontario corn multi-rate N response trials were fitted with a quadratic-plateau model that provided estimates of maximum yield response to nitrogen (YRTN) and the associated N rate at which it occurs (Nmax). Estimates of economically optimum N rates are based on a rectangular hyperbolic relationship between YRTN and agronomic efficiency of N (kg Grain/kg N applied) at Nmax (r2= 0.55). The maximum potential agronomic efficiency of N (AE) is estimated at 63 kg Grain/kg N applied. Increasing YRTN is associated with increasing AE. AE is also increased by about 8% when N was sidedress applied at growth stage V5-V8 compared to spring pre-plant applications. The potential exists for integrating two rate, YRTN estimations of optimum N rates on a site specific basis in order to verify N rate recommendations.
See more from this Division: ASA Section: Agronomic Production SystemsSee more from this Session: Adaptive Nutrient Management: I