生态保育措施对三峡库区小流域地表氮磷排放负荷的影响

Effects of Ecological Conservation Measures on Surface Nitrogen and Phosphorus Loss Load in the Three Gorges Reservoir Area

为优化三峡库区农业面源污染和水体富营养化防控措施,提高库区水土保持效果和生态环境效益,本试验通过对比传统措施(顺坡耕作+玉米/水稻秸秆回收+榨菜菜叶还田)和生态保育措施(横坡等高耕作+水稻/玉米秸秆—榨菜菜叶还田+水旱农桑配置)的氮磷流失动态特征和排放负荷,发现生态保育措施氮磷排放负荷在玉米/水稻季分别降低4.95~5.60kg hm^(-2)和0.09~0.10 kg·hm^(-2),榨菜季分别降低4.58~5.18 kg·hm^(-2)和0.04~0.05 kg·hm^(-2),全年单位面积全氮和全磷排放负荷消减比例分别为69.68%~69.70%和66.67%~70.01%;径流量与土壤氮排放量均受降雨量显著影响,而磷排放量受降雨影响较小;径流量、氮素及磷素累积规律相似,但生态保育措施氮磷累积幅度显著小于传统措施。综上可知,生态保育模式能够有效消减地表氮磷流失,降低土壤氮磷排放负荷。

In order to optimize agricultural non-point source pollution and water eutrophication in the Three Gorges Reservoir area,and improve effects of the soil and water conservation and ecological environment benefits,experimental treatments,which consist of traditional measure(downslope tillage + maize/rice straw recycling +Preserved Szechuan Pickle leaves returning) and ecological conservation measures(contour tillage + maize/rice straw-Preserved Szechuan Pickle leaves returning +crop and mulberry configuration),were designed.The results showed that nitrogen and phosphorus loss load in ecological conservation measures declined by 4.95~5.60 kg·hm^(-2)and 0.09~0.10 kg·hm^(-2)of maize/rice season,and by 4.58~5.18 kg·hm^(-2)and 0.04~0.05 kg·hm^(-2)of Preserved Szechuan Pickle season,the annual total nitrogen and total phosphorus loss load removing ratios per unit area were69.68%~69.70% and 66.67%~70.01%,respectively;runoff and soil nitrogen loss were significantly affected by precipitation,while phosphorus loss was not;accumulation of runoff,nitrogen and phosphorus was similar,but the accumulation of nitrogen and phosphorus in ecological conservation measures was significantly less than those of the traditional measures.In summary,the ecological conservation mode effectively declined loss load of nitrogen and phosphorus.