滇池流域农田土壤氮磷流失分析研究

Farmland Runoff of Nitrogen and Phosphorus in Dianchi Watershed

采用实地调查与田间模拟实验相结合的方法,研究了滇池流域沿湖15个乡镇农田地表径流氮、磷流失状况及其影响因素。结果表明,研究区农田地表径流氮、磷污染负荷很高,年均流失量差异较大,总氮为5.07-113.16 kg/hm^2,总磷为0.15-10.14 kg/hm^2。高强度的化肥施用是造成农田径流氮、磷流失量大的主要原因,同时也与土地利用方式、水肥管理方式及种植制度有关;不同坡度农田径流中氮、磷的输出量不同,从6°-12°氮、磷流失急剧增大,12°以后流失量增加减缓;无论在一次降雨中,还是在作物生长周期内,径流中氮、磷流失速率均表现出随时间参数增加而递减的趋势;施肥处理不同,氮、磷流失量存在一定差异,其中尿素与普钙配合施用可减少氮、磷流失,同时获得较高的白菜产量。

Means of field survey and simulation test, the present status and influent factors of nitrogen and phosphorus loss from farmland runoff were studied around Dianchi Lake 15 villages and towns. The result showed that the pollutional loads of nitrogen and phosphorus in farmland runoff in the investigated area were high, the mean annual discharge of nitrogen and phosphorus was different greatly, total nitrogen 5.07-- 113.16 kg/hm^2, total phosphorus 0.15-10. 14 kg/hm^2. Excessive application of fertilizer was the primary reason of nitrogen and phosphrous loss largely,which was also related to land use pattern, water and soil management, farming system. The discharge of nitrogen and phosphorus varied with slopness, increased rapidly from 6^o to 12^o and increased slowly from greater than 12^o. Whether in once rainfall or in crop growth period, the concentration of nitrogen and phosphorus in the runoff submitted to downtrend follow temporal process. The discharge of nitrogen and phosphorus varied with different fertilizer application, urea and superphosphate application could reduce nitrogen and phosphorus loss and heighten cabbage yield.