Effects of nitrogen application and irrigation on grain yield, water and nitrogen utilizations of summer maize

A field experiment using the splitplot design was carried out to investigate the effects of nitrogen and irrigation on growth of summer maize, yield components, and water and nitrogen use efficiencies. There were three irrigation levels, 900 (W900), 1200 (W1200), and 1500 m3/ha (W1500) in main plots and four nitrogen levels, 0(N0), 150 (N150), 210 (N210), and 270 kg/ha (N270) in subplots. The results show that the effects of nitrogen and irrigation on grain yield, yield components (grains per spike, 100-grain weight and grain weight per spike), harvest index (HI) and aboveground dry matter at each growth stage of summer maize are not significantly different when the irrigation rate is higher than 900 m3/ha and the nitrogen application rate is higher than 150 kg/ha. The nitrogen agronomic efficiency (NAE) and partial factor productivity of the applied N (NPFP) are decreased with the increase of the nitrogen application, and the water productivity (WF) and water use efficiency (WUE) are also decreased significantly with the increase of the irrigation rate (900 m3/ha1200 m3/ha1500 m3/ha). In the present experiment, the optimal combination of nitrogen rate and irrigation rate is W900N150 for the higher grain yield, yield components and water use efficiency, which has lower potential harm for environment.