Enhancing nitrogen use efficiency and yield of maize (Zea mays L.) through Ammonia volatilization mitigation and...

Management of nitrogen (N) fertilizer is a critical factor that can improve maize (Zea mays L.) production. On the other hand, high volatilization losses of N also pollute the air. A field experiment was established using a silt clay soil to examine the effect of sulfur-coated urea and sulfur from gypsum on ammonia (NH₃) emission, N use efficiency (NUE), and the productivity of maize crop under alkaline calcareous soil. The experimental design was a randomized complete block (RCBD) with seven treatments in three replicates: control with no N, urea₁₅₀ alone (150 kg N ha^-1), urea₂₀₀ alone (200 kg N ha^-1), urea₁₅₀ + S (60 kg ha^-1 S from gypsum), urea₂₀₀ + S, SCU₁₅₀ (sulfur-coated urea) and SCU₂₀₀. The results showed that the urea₁₅₀ + S and urea₂₀₀ + S significantly reduced the total NH₃ by (58 and 42%) as compared with the sole application urea₂₀₀. The NH₃ emission reduced further in the treatment with SCU₁₅₀ and SCU₂₀₀ by 74 and 65%, respectively, compared to the treatment with urea₂₀₀. The maize plant biomass, grain yield, and total N uptake enhanced by 5-14%, 4-17%, and 7-13, respectively, in the treatments with urea₁₅₀ + s and urea₂₀₀ + S, relative to the treatment with urea₂₀₀ alone. Biomass, grain yield, and total N uptake further increased significantly by 22-30%, 25-28%, and 26-31%, respectively, in the treatments with SCU₁₅₀ and SCU₂₀₀, relative to the treatment with urea₂₀₀ alone. The applications of SCU₁₅₀ enhanced the nitrogen use efficiency (NUE) by (72%) and SCU₂₀₀ by (62%) respectively, compared with the sole application of urea₂₀₀ alone. In conclusion, applying S-coated urea at a lower rate of 150 kg N ha^-1 compared with a higher rate of 200 kg N ha^-1 may be an effective way to reduce N fertilizer application rate and mitigate NH₃ emission, improve NUE, and increase maize yield. More investigations are suggested under different soil textures and climatic conditions to declare S-coated urea at 150 kg N ha^-1 as the best application rate for maize to enhance maize growth and yield.