生草覆盖与植物篱技术防治紫色土坡地土壤侵蚀与养分流失的初步研究

水土流失与农业面源污染是三峡库区农业生态环境的关键问题之一．研究采用生物治理的方法具有投资少、操作容易和见效快等特点。采用连续定位监测的方法，以常规旱作花生-小麦和黑麦草-大豆（紫粒苋）为对照，分别设置紫花苜蓿多年生牧草、花生-小麦附设香椿生物篱、花生-小麦附设紫花苜蓿生物篱3个处理，连续3年监测各雨次径流、泥沙和泥沙氮磷养分流失量。结果表明，4～9月份是库首地区早坡地土壤侵蚀和泥沙氮磷养分流失的高峰期，不同利用管理方式下，由于植被覆盖和耕作、施肥措施的不同，造成的土壤侵蚀和氮磷养分流失量有明显的差异。与种植季节性牧草和旱坡地常规小麦-花生模式相比，种植多年生牧草和常规小麦-玉米模式附设香椿植物篱．可以有效地减少土壤和泥沙态氮、磷流失。发展饲草-养殖模式的早坡地，选种多年生饲草，既能实现物质、能量多级利用，又能保持水土；常规旱坡地等高设置经济植物篱笆．同样具有显著的生态效益。

Perennial Alfalfa and Contour Hedgerow on Reducing Soil, Nitrogen and Phosphorus Losses from Uplands of Purple Soil

Soil erosion and agricultural non-point source pollution is one of the key eco-environment problems for uplands agriculture in the Three Gorges Region.Biological methods,characterized by little cost,easy for operation,and effective quickly,should be suggested to alleviate the eco-environment problem.Substitute crop of perennial alfalfa and Contour Hedgerow Technology were tested in this research on the effect of reducing soil,nitrogen and phosphorus losses from upland of purple soil.Five treatment plots were set up,and the runoff,sediment,nitrogen and phosphorus losses through sediment by each rainfall event were monitored for each plot from January 19,2002 to November 27,2004.The treatments are perennial alfalfa,ryegrass rotates with soybean,wheat rotates with peanut and Toona sinensis Roem contour hedgerow,wheat rotates with peanut and alfalfa contour hedgerow,and wheat rotates with peanut.The research showed that annually 68.00%~81.80% of the regional precipitation distributed from April to September,and most of the soil erosion,nitrogen and phosphorus losses occured at this period.Substitute perennial alfalfa and contour hedgerow technology are effective in reducing soil erosion and sedimentary nitrogen and phosphorus losses.