Blending of slow-release N fertilizer and urea improve rainfed maize yield, nitrogen use efficiency while reducing apparent N loss

Abstract Background and Aims Effective nitrogen (N) management practices are essential for achieving efficient and sustainable agricultural production. The purpose of this study was to improve N use efficiency (NUE) and minimize N loss by optimizing the rate and type of N fertilizer application, while maintaining high yield of maize. Methods A two-year field experiment with U (urea), S (slow-release N fertilizer), and SU (Blending of S and U) under four N application levels (N1: 90 kg ha⁻¹, N2: 120 kg ha⁻¹, N3: 180 kg ha⁻¹, N4: 240 kg ha⁻¹) was conducted to investigate their effects on ammonia (NH₃) volatilization, residual soil nitrate N (NO₃⁻-N), yield, NUE, apparent N loss of rainfed maize. Results NH₃ volatilization in SU and S were 38.46% and 16.57% lower than that in U, respectively. SU and S were found to reduce the apparent N loss by 42.98% and 62.23%. SU decreased NO₃⁻-N leaching in deep soil, and increased NO₃⁻-N content in topsoil. Compared with U and S, SU significantly increased yield, plant N accumulation and NUE. SUN4 achieved the maximum maize yield and plant N accumulation, averaging 7968.36 kg ha⁻¹ and 166.45 kg ha⁻¹. In addition, mixing ratio of U and S was 53%-58%, which was the best ratio for high yield and NUE. Meanwhile, N fertilization with 150-220 kg ha⁻¹ can keep high yield and NUE. Conclusion The findings highlight SU effectively reduced N application rate and was an optimized N fertilization strategy for high yield and N efficient utilization of rainfed maize.