Evaluation of Enhanced Efficiency Nitrogen Fertilizers on Corn Production Systems in the Mid-South

Abstract

Nitrogen (N) is often the most yield limiting nutrient, particularly in corn (Zea mays L.) production systems. In the Mid-South, high N application rates have the potential to lead to high N loss. To minimize this loss, proper N management should focus on improving N use efficiency (NUE) while optimizing productivity. The potential to achieve both tasks can be met using enhanced efficiency N fertilizer (EENF). However, limited research has directly compared the active chemicals in EENFs for corn production in the Mid-South. A study was conducted in 2013 and 2014 at two locations in Louisiana to determine the effectiveness of EENFs on yield, grain N uptake, and NUE over varying N rates. Corn grain yield significantly increased when using EENFs compared to untreated urea (average of 1.54 Mg ha-1 Winnsboro, LA and 1.30 Mg ha-1 Saint Joseph, LA [P <0.0001]). Two stabilizers paired together (NBPT and DCD) in Super U™, improved yields by nearly 3.0 Mg ha-1 when applied at the recommended N rate. The rate of N transformation was observed in greenhouse experiments, to determine the effectiveness of EENFs over multiple durations of time based on NH4+ and NO3- content in the soil system. While NH4+ concentration declined within 7 days post-application, nitrification inhibitors particularly Instinct had high NH4+ concentration and low NO3- concentration in both trials. This slower transformation minimizes the potential of N fertilizer to be lost. These results suggest crop uptake of N fertilizer would increase with higher NUE. Utilizing EENFs has the potential to increase NUE through specified conditions and time periods.