紫色土坡地不同种植模式下水土和养分流失动态特征

Soil,water and nutrient loss under different cropping systems in purple-soil slope-lands

以径流小区定位监测为基础,研究了紫色土坡地不同种植模式对水、土及养分流失特征的影响。种植试验结果表明:紫花苜蓿+青蒿模式和连翘+紫苏种植模式能较好地保持水土。各小区养分流失表现为:玉米/红苕模式小区地表径流全氮和有效氮含量高于其他小区,玉米/红苕模式和连翘+紫苏模式的小区流失泥沙全氮养分富集度高于其他小区,传统农作模式玉米/红苕通过地表径流和泥沙迁移的全氮流失总量最大,可能造成土壤耕作层肥力下降。观测期间,除由于较强的生物固氮作用,紫花苜蓿+青蒿模式增加了土壤全氮含量外,各种植模式下土壤养分均呈下降趋势,表明各小区均出现较明显的养分流失。试验证明:由于传统农作方式水土流失量最大,导致养分流失量大,对环境有较大影响。因此应注意减少传统农作方式中的地面扰动,并提高雨季地表覆盖率,从而保证农业生产的可持续发展。

Four cropping systems, Dioscorea opposita Thunb ＋ Capsicum frutescen （ P1 ） , Zea mays L. / Ipomoea batatas Lam （ P2 ） , Medicago sativa ＋ Artemisia apiacea Hance （ P3 ） , Perilla frutescens ＋ Forsythia suspense （ P4 ） , were investigated for soil nutrient loss via surface runoff and sedimentation. The study shows that P3 and P4 cropping systems better preserves soil and water loss than the other two systems. Total N and available N in surface runoff from P2 plot are higher than those from the other three plots. Meanwhile, sediment enrichment with total N in P2 and P4 plots is higher than the other plots. Total N loss from P2 plot is the highest, and may result in decreasing plow-layer soil fertility. Except for P3 plot, where there is increasing soil total N due to the biological nitrogen fixation by M. sativa, all other plots show nutrient decreasing trend during the crop growth, an indication of nutrient loss under the cropping systems during plant growth.