Optimizing Water and Nitrogen Application System to Improve Nitrogen use Efficiency and Ensure Sustainable Yield of Summer Maize (Zea mays L.)

Exploring the optimal method of water and fertilizer application and N application rate for summer maize is important for achieving the high water and N efficiency in the North China Plain. We tested that the hypothesis that optimizing water and nitrogen application system could improve nitrogen (N) use efficiency and water productivity, and ensure sustainable yield of summer maize. The results showed that: the 216 kg N ha-1 of drip irrigation (DI) and micro-sprinkling irrigation (SI) could obtain the high grain yield compared with 270 kg N ha-1 of flooding irrigation (FI), which was achieved by maintaining a high 1000-grain weight and kernel number. However, the grain yield of 162 kg N ha-1 would be decreased significantly. Irrigation methods and N application rates had significant effects on the ammonia volatilization rate and ammonia volatilization accumulation of soil, N harvest index (NHI), N partial productivity and water productivity. Compared with FI, DI and SI could reduce the ammonia volatilization rate through applying little fertilizer-N by times, and reduce the ammonia volatilization accumulation of 19.5%-54.9%. In addition, under the same irrigation method, the NHI reached the maximum when the N application rate was 216 kg ha−1. Considering comprehensively, under the condition of this experiment, 216 kg N ha−1 is the best N application rate under DI or SI for maize.