昆明市松华坝水源区不同利用类型坡地氮素输移规律研究

采用径流小区法对昆明市松华坝水源区牧羊河中游5种不同利用类型坡地地表径流及流失土壤的N（氮）素输移情况，在2007年雨季进行了观测分析。结果表明:不同利用类型坡地N素流失量和水土流失量具有一致性，径流泥沙中，N素流失量分别是裸地>豆地>马铃薯地>林地>草地；径流中，N素流失量依次为裸地>豆地>马铃薯地>林地>草地；5种不同利用坡地截流能力依次为草地>林地>马铃薯地>豆地>裸地。随着截流能力的提高，其径流流失量和土壤侵蚀呈递减趋势，因而N素流失量也逐渐减少；其次，坡度、施肥及土壤自身N素含量也是影响土壤N素流失的重要因素，因此控制水源区水土流失是控制由于N素流失而引起的面源污染的主要途径。

Nitrogen Loss Characteristics in Different Use Slope Field in Songhua Dam Reservoir of Kunming

The nitrogen transformation in the soil erosion and runoff of different use slope field had been observed in rainy season in the middle reaches of Muyang river of Songhua dam reservoir in Kunming. The results showed that the nitrogen loss amount was consistent with loss amount of soil and water in different use slope field, the nitrogen loss in the erosion soil was bare plot>bean plot>tomato plot>forest plot>grass plot, and in the runoff bare plot>bean plot>tomato plot>forest plot>grass plot respectively. The cut-off ability of different use slope field was grass plot>forest plot>tomato plot>bean plot>bare plot respectively, and that of runoff loss and soil erosion loss decreased with the cut-off ability increasing, which lead the nitrogen in runoff and soil erosion to be reduced gradually. Secondly, the nitrogen content in soil, gradient and fertilization are important reasons of nitrogen loss. So, to control soil and water loss is to control non-point source pollution because of nitrogen loss.