紫色土旱坡地氮流失通量对减肥配施秸秆的响应

紫色土旱坡地被认为是三峡库区泥沙和面源污染的主要来源地，加强对紫色土旱坡地壤中流和地表径流中氮流失特征的研究，对防控三峡库区的面源污染有重要的现实意义.依托中科院成都山地所忠县石宝寨试验站的紫色土旱坡地定位径流小区，设置不施肥（CK）、常规施肥（T₁）、优化施肥（T₂）和减肥配施秸秆（T₃）这4种不同的处理，通过监测在油菜-玉米轮作制度下紫色土旱坡地壤中流和地表径流的流失通量、各次径流不同氮形态的流失浓度和流失通量，研究紫色土旱坡地氮流失通量对减肥配施秸秆的响应.结果表明，壤中流径流量占总径流量的比例达到60.14%~88.56%，壤中流氮流失通量占全氮流失通量的72.88%~92.35%.铵态氮主要通过地表径流的方式流失，硝态氮主要通过壤中流的方式流失且是氮流失的主要形态.不同处理的铵态氮和硝态氮流失通量均呈现出T₁ > T₂ > T₃ > CK，T₃处理的氮流失通量为20.07 kg·（hm²·a）^-1，较T₁和T₂分别下降了43.59%和39.55%.减肥配施秸秆显著降低了紫色土旱坡地铵态氮、硝态氮和全氮的流失通量，对紫色土旱坡地雨季径流中氮流失有显著的消减效应.

Response of Nitrogen Loss Flux in Purple Soil Sloping Field to Reduced Fertilizer and Combining Straw

The purple soil sloping field is considered as the main source of sediment and non-point source pollution in the Three Gorges Reservoir area. To prevent and control the non-point source pollution, it is indispensable to explore the characteristics of nitrogen loss in the overland flow and interflow of purple soil sloping field in Three Gorges Reservoir area. The purple soil sloping runoff plots, located in the Shibaozhai Experimental Station of Chengdu Institute of Chinese Academy of Sciences in Zhongxian County, Chongqing, were studied. The experiment included no fertilization treatment (CK), traditional fertilization treatment (T₁), amended fertilization treatment (T₂), and reduced fertilizer with straw treatment (T₃). According to the data of volume of the interflow and runoff and the leach concentration and flux of nitrogen forms under rapeseed-maize rotation system, the response of nitrogen leaching flux to reduce fertilizer with straw application can be definite in purple soil sloping plots. The results show that the ratio of interflow to total runoff is 60.14%-88.56%, and the flux of nitrogen leaching in the interflow accounts for 72.88%-92.35% of total nitrogen loss flux. Ammonium was mainly leached by the overland flow. In addition, nitrate was mainly leached by the interflow and was the main form of nitrogen leaching. The fluxes of ammonium and nitrate under different treatments followed the order T₁ > T₂ > T₃ > CK. The total nitrogen flux of T₃ was 20.07 kg·(hm²·a)^-1, which was 43.59% and 39.55% lower than that of T₁ and T₂, respectively. The reduced fertilizer with straw application significantly decreased the leaching flux of ammonium, nitrate, and total nitrogen, and weakened the effect on runoff nitrogen leaching in the purple soil sloping plots.