1a.Objectives (from AD-416):
To use labeled fertilizer nitrogen (N) applied to corn to quantify the ability of a winter wheat commodity cover crop (wheat without fall N fertilizer) vs. a traditional winter wheat crop (wheat with fall fertilizer N) to scavenge corn residual nitrate N, and to compare the fertilizer N uptake efficiencies of two modern corn hybrids, one with and one without multiple pest-resistant genomics.
1b.Approach (from AD-416):
Two field-plot experiments will be conducted, each with a two year corn-wheat rotation. The corn treatments will be six rates of 15N labeled fertilizer on each of two corn hybrids, one with and one without multiple pest-resistant genomics. The corn fertilizer N uptake efficiencies of each hybrid will be determined by total 15N uptake at physiologic maturity, as well as grain 15N removal. After corn harvest, soil samples will be taken to determine the quantity of labeled N remaining in the root zone. Fall winter wheat will be established on all plots with half the plots receiving no fall fertilizer-N (commodity wheat cover crop), and the other half receiving the recommended rate of unlabeled fertilizer-N (traditional winter wheat). All wheat will be grown to maturity with grain and straw samples collected for determining the total recovery of the fall residual-15N by each winter wheat system. These data will provide estimates of the N uptake efficiency of two modern corn hybrids, and the ability of a wheat commodity cover crop vs. a traditional wheat crop to recycle corn residual N in this grain-cropping system.
Excellent progress has been made toward achieving the objectives of this research and implementing the above approaches. The specific progress tasks that have been completed include: the review of several possible sites for the research, the final selection of a site, the collection of initial soil samples, the planting and establishment of the two corn cultivars, and the application of six rates of labeled fertilizer N to the corn. Research is progressing well, as planned.