Interaction offset the adverse impacts of water and nitrogen reduction on nutrient accumulation and utilization of summer maize

Objectives  Irrigation and nitrogen application are two key factors which sustain summer maize yield in Guanzhong plain, however, over fertilization and irrigation are common in this region. We studied the optimum water and N rate for efficient water and fertilizer use.

Methods A split plot trial of summer maize was conducted in Yangling, Shaanxi Province in 2018–2019. Three irrigation levels were traditional 800 m³/hm² (W2), 400 m³/hm² (W1) and no irrigation (W0). Under each water treatment were the five N rate treatments, 300 kg/hm² (N300), –25% (225 kg/hm²), –50% (150 kg/hm²), –75% (75 kg/hm²) and no N fertilizer (0), respectively. The W2N300 treatment under traditional irrigation mode served as control. Maize yield, accumulation and translocation of N, P, K, and nitrogen use efficiency under different water and nitrogen reduction treatments were analyzed.

Results W2N225, W1N225, and W1N150 treatments produced similar maize yields and yield components with W2N300. Compared with W2N300, W1N225 significantly enhanced the dry matter accumulation after tasseling stage, enhanced the nutrient accumulation after tasseling stage and their proportion in total uptakes, but there was no significant difference from those of W2N225 and W1N300. N and irrigation level exhibited significant interaction on dry matter remobilization and nutrient translocation. Compared to W2N300, W1N225 significantly increased dry matter and N, P, and K translocation after tasseling stage by 11.67%, 16.28%, 19.80%, and 18.95%. Correlation analysis showed significant relationship between yield and N, P and K accumulation before and after tasseling stage, and the P values after tasseling stage were higher than before tasseling stage.

Conclusions Proper water and nitrogen levels have significant interaction on the dry mater and nutrient accumulation after tasseling stage of maize, that offset the adverse impacts of reducing irrigation and nitrogen inputs, as maize yield is significantly correlated with the nutrient accumulation and translocation of N, P, K after tasseling stage, thus increases nitrogen and water use efficiency. A combination of 400 m³/hm² and N 225 kg/hm² is optimum irrigation and nitrogen rates respectively in Guanzhong Plain irrigation region.