中文摘要：

通过设置在甘肃省定西市安定区李家堡镇的长期免耕条件下不同施肥制度对春小麦氮肥后效试验点，研究了免耕条件下不同施氮制度对春小麦氮肥后效及最佳施肥量，采用氢氧化钠一硼酸碱解扩散法测定0-200cm土层土壤碱解氮的含量．结果表明：在免耕条件下，经过7年不同施氮水平处理，各处理表层0-10cm土层碱解氮含量均高于其他土层，占整个土层碱解氮总量的28．82％，土壤碱解氮含量具有明显的表聚现象。由各处理0-200cm土层的碱解氮含量对比后，得出当季的施肥量对0-110cm土层碱解氮含量影响明显，且后效显著；同时在各种施氮水平中施氮量105kg／hm。时为最佳施氮水平。为陇中黄土高原丘陵沟壑区雨养农田科学合理的使用氮素化肥及提高氮肥利用率并评估农田土壤环境质量提供科学依据。

英文摘要：

Based on the nitrogen aftereffect test of the spring wheat in long-term No-till System of different nitrogen system in Lijiabu town, Anding district, Dingxi of Gansu province, Study the different nitrogen system nitrogen aftereffect test and the best nitrogen rate of the spring wheat, by determining 0-200 cm soil nitrogen content with the diffusion method of sodium hydroxide-borate alkaline hydrolysis, the results showed that： by long-term No-till, ＇after 7 years＇ different nitrogen system treatment, the 0-10 cm treated soil layer nitrogen contents were higher than other layers, accounting for 28.82% of the total soil nitrogen content, which revealed an obvious phenomenon of surface layer accumulation. By contrasting the content of 0-200 cm soil nitrogen, it concluded that the fertilizer rate of the first cropping season had an obvious effect on the content of 0-110 cm soil nitrogen and its aftereffect was significant; the nitrogen rate of 105 kg/hm^2 was the best. In order to provide the scientific basis for the rain-fed farmland to use nitrogen fertilizer reasonably,enhance the efficiency of nitrogen fertilizers and assess the quality of farmland soil environment in hilly and gully regions in middle gansu region of loess plateau.