氮肥运筹对限水灌溉冬小麦产量及氮素利用的影响

华北地区是中国小麦的主产区，也是缺水最为严重的地区之一，农业用水用肥过量正威胁着这个地区地下水资源的数量和质量。为此，笔者于中国农业大学吴桥实验站研究了不同氮肥措施对冬小麦产量、氮素和水分利用、以及土壤硝态氮残留的影响。实验在春浇一水和春浇二水两种水分限制条件下，分别设7个氮肥处理，即在4个等级氮肥用量（分别为0、157.5kg/hm2、226.5kg/hm2、295.5kg/hm2，不包括有机肥中所含氮量）下，分设两种施肥方式（全部基施和基施+追施）。结果表明，施氮量和施氮方式相同时春浇二水冬小麦的产量高于春浇一水，二水穗粒数较一水高，千粒重则低于一水，一水耗水量较少，水分利用效率明显高于二水；同一水分下不同施肥量及施肥方式对产量的影响差异不显著，同一施肥方式下在157.5-295.5kg/hm2范围内，施肥量越大，氮素生理效率和氮肥生产力越低，施氮157.5kg/hm2时，氮收获指数均处在最高或较高水平；土壤硝态氮残留量与施氮量呈显著正相关，成熟期一水条件下土壤中硝态氮主要集中在上层(0~80cm)，二水条件下则主要分布在中下层。综合研究表明，在春浇一水条件下，施氮水平在157.5kg/hm2，且全部基施，能够获得与多量施肥相当的产量，且可提高氮肥和水分利用效率，减少硝态氮的淋洗和残留，提高劳动生产率，在干旱缺水地区是比较合理的栽培方式

Effect of Nitrogen Applications on Grain Yield and Nitrogen Use Efficiency of Winter Wheat in Limited Water Supply

Application of N fertilizer and water are the most important measures that increase grain yield of wheat. The field experiment was carried out to study the effect of nitrogen application on grain yield of winter wheat, efficiency of nitrogen and NO3--N accumulation in soil at Wuqiao Experimental Station of China Agricultural University. A randomized complete block design was used with three replications with the cultivar Jinan17 in two irrigation modes. There were four nitrogen rates(0、157.5kg/hm2、226.5kg/hm2、295.5kg/hm2) and two methods(basal nitrogen application and split nitrogen application) within seven treatments. The results showed that the grain yield of winter wheat with two-irrigation was higher than that with one-irrigation with the same nitrogen application rate and method. Compared to one-irrigation，the grain number per spike in two-irrigation was higher，the 1000-grain weight was lower, the water wastage was higher, but the WUE was lower. The yield was not affected significantly by nitrogen rates and the methods. Within the nitrogen rate of 157.5-295.5kg/hm2， the lower NUPE and Nitrogen Productivity declined with nitrogen rate increasing. NHI was not lower than the others at the lowest nitrogen rate of 157.5kg/hm2. The accumulation of NO3--N in soil was significantly and positively correlated with the nitrogen application rate. NO3--N in one-irrigation was distributed mainly in the top layer (0-80cm), but it was inverse in two-irrigation. It was concluded that it is the most reasonable cultivation mode in water-limited area to apply one-irrigation，nitrogen application rate of 157.5kg/hm2 as basal fertilizer，which not only increased the nitrogen and water utilization efficiency，but also deceased the leach and the accumulation of NO3--N in soil.