浅湿晒灌溉时不同施肥水平对稻田氮素运移及产量的影响研究OA

[Objective]Optimizing fertilization under water-saving irrigation can improve rice yield and nitrogen-use efficiency while reducing nitrogen losses.This study investigated the effects of fertilizer application rate on soil nitrogen dynamics and rice yield under shallow-wetting-drying irrigation to find an optimal irrigation-fertilization strategy for simultaneously improving rice yield and nitrogen-use efficiency.[Method]The experiment was conducted in five paddy fields under shallow-wetting-drying irrigation.Fertilization treatments were as follows:slow-release fertilizer(ω(N):ω(P):ω(K)=24:8:10),urea(ω(N)＞46％),and compound fertilizer(ω(N):ω(P):ω(K)=26:10:15)were applied as basal fertilizer and topdressings at the jointing and booting stages,respectively.Fertilizer application rate in four fields was set at 100％,90％,85％,and 80％of the conventional fertilization rate,and one unfertilized field served as the control.The spatiotemporal distributions of NH4+-N and NO3--N in the 0-30 cm soil layer,as well as rice yield and nitrogen-use efficiency,were measured for each treatment.[Result]NH4+-N and NO3--N concentrations peaked following each fertilizer application.NO3--N concentrations were significantly lower than NH4+-N concentrations,and the peak in NO3--N concentration generally lagged behind that of NH4+-N,except under the conventional fertilization rate.Overall,reducing fertilization rate by 10％relative to the conventional fertilization rate resulted in the most stable spatiotemporal distributions of NH4+-N and NO3--N,and achieved the highest rice yield and nitrogen-use efficiency.[Conclusion]Under shallow-wetting-drying irrigation,reducing fertilizer application by 10％relative to the conventional fertilization rate was most effective,increasing both rice yield and nitrogen-use efficiency.This irrigation-fertilization strategy reduced nitrogen losses through gaseous emissions and leaching by regulating the spatiotemporal dynamics of soil nitrogen.