氮肥管理与地膜覆盖对旱地冬小麦产量和氮素利用效率的影响

降雨偏少且季节分布不均,施肥偏多且方式不合理,缺少有效的保水栽培措施是西北旱地小麦生产面临的主要问题。2010年10月至2012年6月连续2个小麦生长季,在陕西渭北旱塬进行田间试验,比较了氮肥追施和总量减少、覆膜、增加种植密度措施较传统施肥和农民习惯施肥种植模式对冬小麦籽粒产量及氮素利用效率的影响。与农户习惯施肥相比,传统施肥不能持续增加产量和氮素利用效率;而减氮追肥、减氮垄覆和减氮垄覆增密处理的增产效果明显,同时提高了氮素利用效率,但减氮垄覆或增加种植密度却使籽粒含氮量降低,主要原因是进入开花期后土壤硝态氮累积量减少,氮素供应不足所致。综合分析,减氮垄覆增产增效更明显,小麦产量、氮肥偏生产力、氮肥生理利用率在第1年分别提高38.6%、49.6%和35.1%,在第2年分别提高7.6%、16.3%和25.7%,说明控氮与覆膜结合是实现旱地冬小麦增产的重要措施,但需注意生长后期土壤氮素供应,在增产的同时保证小麦品质。

Effects of Nitrogen Fertilizer Management on Yield and Nitrogen Use Efficiency in Winter Wheat Growing on Dryland with Plastic Film Mulching

Wheat production in Northwest China is mainly restricted by insufficient and uneven distributed precipitation across seasons. Besides, luxurious and improper application of nitrogen (N) is an obvious problem. In a two-year field experiment from October 2010 to June 2012, we compared grain yield and N use efficiency of winter wheat with cultivation patterns of conventional fertilization (P), current farmer’s habitual fertilization (C), reducing N with early-spring topdressing (NT), NT + ridging and mulching with plastic film (NR), and NR+ high plant density (NRH). Compared with P treatment, C had no effect on stable increases of grain yield and N use efficiency, while NT, NR, and NRH treatments significantly increased yield and N use efficiency of wheat. However, N content in grain was reduced in NR and NRH treatments. In an overall view, NR was the optimal treatment for high-yield and high-efficient wheat production, with the increases of grain yield, N partial factor productivity, and N physiological efficiency by 38.6%, 49.6%, and 35.1% in the first cropping year and by 7.6%, 16.3%, and 25.7% in the second year, respectively. These results indicate that N management plus ridge mulching is an important technique for high-yield production in Northwest China, and suitable N supply after flowering should be considered for high quality also.