Exploring optimal nitrogen management for high yielding maize in arid areas via 15N-labeled technique

Abstract

A quantitative understanding of nitrogen (N) fate is a key for designing an optimal integrated N management for a sustainable high yielding maize system. In this study, we explored optimal N application rates and split using the data of a 2-year field experiment (2014–2015) with labeled 15N. The results showed that, plastic film mulch significantly increased grain yield and aboveground N uptake by 14.4% and 7.4% in 2014, and by 27.9% and 18.8% in 2015, respectively, compared to no mulch treatment. High N rate (375 kg ha−1) or high basal N ratio (70%) had no significant effect on grain yield, compared to low N rate of 300 kg ha−1 with low basal N ratio (40%). 42.5–51.4% of urea 15N was recovered by maize total biomass (including roots); 26.1–30.7% of applied urea 15N remained in the 0–160 cm soil layer, and approximately 21.8–27.4% of applied N was unaccounted in the first season (2014). In the second season (2015), 3.8–8.8% of applied urea-N was recovered by succeeding maize. Among all treatments, the split of 120-90-90 with mulch performed best for achieving the high yield and high N use efficiency in irrigated maize system. In conclusion, N fate is significantly affected by mulch, N rate and split in irrigated maize systems in arid area. Plastic mulch significantly increased total maize N recovery and reduced N loss. High N rate and high basal N application led to low N recovery of maize but high N residue in soil. Reducing N input and improving N split are the two effective measures to increase N use efficiency and reduce N loss. High yield and high N use efficiency can be achieved simultaneously with optimal N rate and split, which must consider soil N supply, crop N demand and farming practice as a whole.