Fertilizer Placement Effects on Nitrogen Uptake and Corn Grain Yield.

Current Mississippi State University corn N recommendations suggest knifing N fertilizer in the row middle. While this may avoid root pruning for split N applications, such placement could potentially result in increased N loss, leading to reduced N use efficiency and grain yield. The objective of this research was to evaluate crop N uptake and corn grain yield, as influenced by urea-ammonium-nitrate (UAN) fertilizer placement distance from the corn row. Treatments included ¹⁵N labeled fertilizer applied at 6, 12, and 18 in. distances from the corn row using both surface and subsurface banded application. Following university recommendations, fertilizer N was split-applied, with 50% applied at planting followed by 50% applied at the V6 corn growth stage. Samples included ear leaves at VT, and whole plant and grain samples at physiological maturity for determination of ¹⁵N recovery. Results from this study could potentially help further our knowledge of fertilizer N placement effects on corn N uptake, as well as refine current university N placement recommendations. Initial results will be presented at the ASA Southern Branch 2012 Annual Meeting.