Can a Cover Crop In Continuous Corn Decrease Tile Nitrate Load and Increase Crop NUE?.

In dry-land corn production systems, severe droughts limit plant growth and fertilizer N uptake, increasing the risk of nitrate leaching during the following winter and spring, especially in field containing pattern tile drainage. The objective of this study was to assess the effect of using a cover crop on nitrate leaching and NUE in a continuous corn system. Using a paired watershed approach (adjacent pattern drained fields with individual tile outlets) we planted annual ryegrass with radish on one of the two fields and monitored tile flow and nitrate concentration from both fields for a cover versus no-cover comparison. Following drought conditions that limited corn productivity and N uptake in 2012, the cover crop mix was aerially seeded into standing corn on September 8. Clip plot analysis of the cover crop mix on November 8 determined that above ground biomass production was approximately 2 Mg ha^-1 and contained approximately 60 kg N ha^-1. Cover crop was terminated with glyphosate on April 8, 2013 and corn was planted approximately one month later. Sidedress fertilizer was applied to corn at a rate of 194 and 224 kg ha^-1 for cover and no cover fields, respectively. Tile nitrate loads and corn performance measurements (i.e. NUE) will be detailed and discussed.