Distinct enhanced efficiency urea fertilizers differentially influence ammonia volatilization losses and maize yield

Aims Urea is the most commonly used N fertilizer worldwide, but can easily volatilize as ammonia and be lost from the soil. Enhanced Efficiency Fertilizers (EEFs) have been developed to increase nutrient use efficiency, reduce N losses, and increase crop yield. Methods The efficacy of different EEF urea technologies was compared to untreated urea when surface applied to no-till maize ( Zea mays L.) in three field seasons. Treatments included untreated urea, urea-ammonium nitrate (UAN), polymer-coated urea (ESN and Duration), urea treated with urease inhibitors (Agrotain) and urea treated with both urease and nitrification inhibitors (Nutrisphere and SuperU). Ammonia volatilization, soil nitrogen content and maize yield were determined in order to evaluate EEFs. Results Volatilization losses, measured for 25 days after fertilization (DAF) in the first year, and 25 and 82 DAF in the second and third year, differed among products and years. Polymer-coated urea and urea treated with urease inhibitor effectively reduced ammonia volatilization peaks and resulted in a consequent decrease of ammonia losses at 25 DAF and 82 DAF in most years. The double inhibitor-treated urea (Nutrisphere and SuperU) showed similar ammonia losses as untreated urea. Overall, EEFs maintained maize grain yield produced with untreated urea, except for one polymer-coated urea product which increased yields. Conclusions The efficacy of EEF in mitigating NH 3 losses varied with precipitation and other environmental conditions. We found that the polymer-coated urea presented the best performance reducing ammonia losses and maintaining or even increasing maize grain yields in this study.