冬小麦节水灌溉制度下不同施氮量的氮素平衡

用15N示踪技术研究了节水灌溉条件下冬小麦对不同施氮量的氮素吸收和氮素平衡 ,并比较了两种灌溉制度下小麦对节肥施氮量的吸收动态。结果表明 ,与常规施氮量处理相比 ,节水灌溉条件下节肥施氮量处理的氮肥损失率降低 ,氮肥当季利用率和土壤残留率提高 ;基施氮肥的利用率高于追施氮肥 ;土壤肥料氮的残留率在 2 9%～ 41 %之间 ,分布于 1m土层中 ,其中60 %以上集中在 0～ 2 0cm土层 ;在整个小麦生长季内 ,肥料氮并没有淋洗到 1 30m以下。节肥施氮量在常规灌溉下的当季利用率比在节水灌溉下降低 1 6 6%。

N BALANCE OF DIFFERENT N APPLICATION RATE OF WINTER WHEAT UNDER WATER-SAVING CONDITION

N uptake and N balance of different N rate applied to wheat under water-saving condition were investigated with 15N tracer technique and the dynamic N uptake of economic N treatment under two irrigation conditions was compared. The results showed that (1) compared with conventional N treatment, the N loss of economic N treatment reduced while NUE and N residue in soil improved under water-saving condition;(2) Use efficiency of fertilizer applied as basal fertilizer was higher than that as top-dressing fertilizer under water-saving condition;(3) The fertilizer N residue rate was from 29% to 41%, and 60% of N residue, which distributed in 1m depth soil concentrated in 0～20cm surface layer; (4) In whole growing stage of wheat, fertilizer N hadn't leach to 130cm depth; (5) NUE of economic N treatment under conventional irrigation decreased by 16.6% compared with the same N treatment under water-saving condition.