Effects of Fertilizer Nitrogen Stabilizers on Corn (Zea mays) Grain Yield and Nitrogen Use Efficiency.

Urea-containing fertilizers applied to corn in conservation tillage systems are prone to N loss via NH₃ volatilization, leaching, and denitrification resulting in a reduction in N use efficiency (NUE) and contributing to environmental degradation. Fertilizer N stabilizers, such as urease inhibitors (UI) and nitrification inhibitors (NI), may provide producers options to reduce unpredictable N losses. Substantial research exists on the efficacy of UI and NI’s. However, limited information is available on the effects of fertilizer N stabilizers with liquid UAN and urea under southern climatic conditions. The objective of this study was to determine the effects of fertilizer N stabilizer treated liquid UAN and granular urea on corn grain yield as compared to split (50/50) and single applications of untreated UAN. A field study was conducted on a Marietta fine sandy loam at Mississippi State University for 2013 through 2015. Stabilizer products were applied to UAN (32% N) and urea (46-0-0) at labeled rates for 179.2 kg N/ha. Broadcast urea and subsurface banded UAN were applied at the V2-V3 growth stage. The split sidedress application of UAN was applied at V4-V5. Corn grain yield was adjusted to a moisture concentration of 155 g/kg. Corn grain yield was increased in 2013 and 2015 when UAN was treated with UI + NI compared to the untreated split application of UAN. Stabilizing UAN with either UI or NI did not increase yields compared to a single application of untreated UAN in 2013 or 2014. However, yield increased 0.43 to 2.05 Mg/ha when UAN was stabilized with UI, NI, or UI + NI in 2015. Stabilized urea increased yield 0.54 to 1.1 Mg/ha compared to untreated urea across all years. Overall, fertilizer N stabilizers increased apparent N recovery when applied to either N source. Fertilizer N stabilizers can improve corn grain yield when environmental conditions favor N loss.