Corn Grain Yield and Nitrogen Uptake Response to Preplant Placement of Nitrogen At Different Distances From the Row.

Equipment with RTK Global Positioning Systems correction can provide sub-inch accuracy for fertilizer applications and planting.   When mid-season nitrogen (N) is applied closer to the row, there is a positive response to grain yield. This study was conducted to evaluate the effect of preplant N placement at different distances from maize rows on grain yield, N grain content, and N use efficiency.  Field studies were established at Lake Carl Blackwell (LCB), OK on a Pulaski fine sandy loam (coarse loamy, mixed, superactive, nonacid, Udic Ustifluvents) and at Hennessey, OK on a Bethany silt loam (fine, mixed, superactive, thermic Pachic Paleustolls).  Preplant N rates were 0, 56, 112, and 224 kg N ha^-1, where 224 kg N ha^-1 used as a non-limiting N reference.  Preplant distances from the row included 0, 8, 15, 25, 38 cm and were achieved by using an RTK equipped tractor. Treatments were arranged in a randomized complete block with 3 replications. Grain yield results and conclusions for 2013 growing season will be presented.