Managing Urea Fertilizer for Optimal N Use and Productivity of Corn.

Corn (Zea mays L.) yield is usually limited by nitrogen (N) availability more than any other nutrient in agricultural soils. Urea is the primary source of inorganic nitrogen fertilizer used worldwide, either as a crystalline solid containing 46% N, or a urea-ammonium nitrate solution (UAN, 28-32%). A major caveat, however, to urea as an N fertilizer is its susceptibility to loss through volatilization when applied to the soil surface. Many products are marketed as nitrogen stabilizers to prevent volatilization losses, including Agrotain, Nutrisphere-N, and humic acids. The overall goal of this project was to evaluate the efficacy of different urea-N management products and techniques on the fate of fertilizer N and corn yields. This experiment was conducted in Champaign and Harrisburg, IL in 2016 using a commercially available hybrid planted at 84,000 plants ha^-1. Preplant treatments included 90 and 179 kg ha¹ of N as urea in Champaign and 79 and 157 kg ha^-1 of N as urea in Harrisburg with and without nitrogen stabilizer products. Treatments that received the half- preplant N rates were sidedressed at V8 with the remaining N as UAN using a Y-drop technique with and without nitrogen stabilizer products. Soil samples were taken 3 weeks after the sidedress application for determination of residual ammonium and nitrate. Plants were sampled at maturity to ascertain total aboveground biomass, N uptake, and yield. Results will indicate which urea management techniques, including timing, placement, and/or stabilizer products, impacted the applied N stability, uptake, and final corn grain yield.