黑麦草鲜草翻压还田对双季稻田肥料氮循环的影响

【目的】研究黑麦草鲜草与尿素混施对双季稻田肥料氮利用率及氮循环特征的影响。【方法】利用盆栽15N示踪试验比较总施氮量一致的条件下单施尿素（CF）、半量尿素与半量黑麦草鲜草混施（RGCF）以及不施氮肥（CK）对双季稻产量、氮吸收利用效率、肥料氮素在土壤中残余以及N2O排放的影响。【结果】与CK相比，RGCF和CF显著增加了双季稻生物量和稻谷产量。RGCF与CF相比，水稻生物量和稻谷产量分别增加5.9%和7.3%。 与CK相比，RGCF和CF显著增加了双季稻氮素吸收量。RGCF与CF氮素吸收量无显著差异。与CF相比，RGCF增加了氮素干物质生产效率、氮素稻谷生产效率和氮素农学效率，降低了15N回收率和15N收获指数。RGCF比CF提高了氮素在土壤中的残留率，降低了N2O排放量。【结论】在双季稻体系中，尿素与黑麦草混施能够提高氮素利用效率，改善稻田氮素循环。

Effects of Ryegrass Incorporation on Fertilizer N Cycling in a Double Rice System

【Objective】Effects of N use efficiency and N cycling were examined when the fresh ryegrass residue was applied with urea in a double rice cropping system.【Method】A 15N-labelled pot trail was conducted to estimate the effects of different treatments of urea(CF),half N from urea plus half N from ryegrass residue(RGCF) and the control(CK,no fertilizer) on soil mineral N concentration,rice yield,N use efficiency,N cycling and N2O emission.【Result】Compared to CK,CF and RGCF increased the biomass dry matter and grain yield of double rice.In comparison with CF,RGCF increased rice biomass dry matter and grain yield by 5.9% and 7.3%,respectively.Compared to CK,CF and RGCF increased the total N accumulation of double rice.No significant difference in total N accumulation was found between RGCF and CF.In comparison with CF,RGCF increased N dry matter production efficiency,N grain production and N agronomic efficiency,reduced 15N recovery efficiency and 15N harvest index.When compared with CF,RGCF improved the proportion of 15N fertilizer residue in soil and decreased N2O emission.【Conclusion】Urea application in conjunction with ryegrass residue could increase N use efficiency and improve N cycling in double rice soils.