Optimal Placement of Nitrogen Fertilizer Sources to Improve Corn Growth.

Optimal Placement of Nitrogen Fertilizer Sources to Improve Corn Growth Authors: Tyler W. Steusloff1, Peter P. Motavalli1, Kelly A. Nelson1 1School of Natural Resources, University of Missouri, Columbia, MO 65211 and 2Division of Plant Sciences, University of Missouri, Novelty, MO 63460. The application of nitrogen (N) fertilizers for row-crop production is essential to achieve crop yields that will help meet the demand for food as world population grows. Attention is focused on agriculture management practices that improve N use efficiency to increase corn yields. Application of N fertilizers can differentiate between placement strategies such as broadcasting uniformly over the soil surface, banding the fertilizer in the soil profile near the root zone, or injection. This study was conducted in Northeastern Missouri at the University of Missouri-Greenley Memorial Research Center on a poorly drained claypan soil starting in 2014. The objective of this research was to determine the effectiveness of different N fertilizer placement practices corn yields. The N fertilizer strategies utilized in this study consisted of five replications of deep banded urea (UDB) or urea plus a nitrification inhibitor (UDB+NI) at a depth of 20 cm compared to urea broadcast surface applied (USA) or incorporated to a depth of 8 cm (UAA). Corn grain and silage yields were collected form each plot for determination of test weight, grain moisture, and analysis of starch and protein concentration. Corn grain yields in 2016 were much higher on average than 2015 but slightly lower than 2014. Excessive rainfall in 2015 caused corn grain yields to be on average 47% lower in 2015 compared to those in 2014. Corn grain yields were higher for UAA, UDB, and UDB+NI in both 2016 and 1014. The UDB+NI was the most consistent in obtaining higher yields among the N placement practices evaluated from 2014 to 2016. Results indicate that response to N fertilizer placement was affected by climatic conditions, the timing of rainfall events and soil moisture content.