【摘要】 [目的]揭示三峡库区紫色土坡耕地表土可蚀性特征,为水土保持措施空间配置优化设计提供依据。[方法]以无措施坡耕地为对照,选取紫色土区埂坎、水平沟坡耕地为研究对象,采集表土测试机械组成和有机质含量,利用EPIC(environmental policy-integrated climate)模型计算可蚀性指标,比较3种坡耕地表土的颗粒组成、有机质含量和可蚀性指标。[结果]①紫色土坡耕地表土粉粒含量较高,黏粒含量较低,分别为45.78%～76.29%和6.05%～10.58%。坡面尺度内,埂坎坡耕地上地块下坡位表土粉粒含量明显高于紧邻的下地块上坡位,砂粒含量则相反。地块尺度内,上坡位砂粒含量较高,中下坡位粉粒含量和黏粒含量较高。②紫色土坡耕地表土有机质含量为0.61%～1.48%。坡面尺度内,埂坎坡耕地上地块下坡位表土有机质含量明显高于紧邻的下地块上坡位。地块尺度内,有机质主要在中下坡位富集。③紫色土坡耕地表土可蚀性K值介于0.043 8～0.059 2之间。坡面尺度内,埂坎和水平沟坡耕地下地块上坡位表土可蚀性K值分别比紧邻的上地块下坡位低16.55%和6.30%。地块尺度内,中下坡位的表土可蚀性K值较大,且最高值出现在坡面的3/4处。表土可蚀性K值与粉粒含量呈极显著正相关(p<0.01),与砂粒含量呈极显著负相关(p<0.01)。[结论]三峡库区紫色土坡耕地表土抗蚀能力较弱,埂坎和水平沟均具有较好的水土保持效果,对提高坡耕地抗蚀性具有一定作用。更多还原

【Abstract】 [Objective] The erodibility of topsoil on purple soil sloping farmlands in the Three Gorges reservoir area was investigated in order to provide a basis for spatial allocation design of soil conservation measures. [Methods] Two different kinds of purple soil sloping farmlands with soil bunds, horizontal ditch were selected, and topsoil was collected to determine the particle composition and organic matter content. Then the soil erodibility index was calculated by the environmental policy-integrated climate(EPIC) model, as to compare the particle composition, organic matter content and erodibility of the topsoil on purple soil sloping farmlands with different soil conservations. [Results] ① The content of silty particle in the topsoil of purple soil sloping farmlands was higher, and ranged from 45.78% to 76.29%, while the content of clay particle was relatively lower, ranged from 6.05% to 10.58%. At the slope scale, silty particle content at the lower slope of the upper field was significantly higher than that at the uphill position of the adjacent downhill plot, while sandy particle content was the opposite. At the field plot scale, sandy particle content was higher in the upper slope, and silty particle content and clay particle content were both higher in the middle and lower slope. ② The content of soil organic matter in topsoil on purple soil sloping farmlands ranged from 0.61% to 1.48%. At the slope scale, the organic matter content in topsoil of the lower slope of the upper field was significantly higher than that in the upper slope of the adjacent downhill plot. At the field plot scale, the organic matter content in the topsoil was mainly concentrated in the middle and lower slope. ③ The erodibility K value of topsoil on purple soil sloping farmlands was ranged from 0.043 8 to 0.059 2. At the slope scale, the erodibility K value at the upper slope of the lower slope of ridge and horizontal gully farmland was 16.55% and 6.30% lower than that at the lower slope of the adjacent upper field, respectively. At the field plot scale, the erodibility K value was higher in the middle and lower slope. The highest value occurred at the 3/4 of the slope. The erodibility K value of topsoil was positively related to silty particle content(p<0.01), while negatively related to sandy particle content(p<0.01). [Conclusion] The anti-erosion capability of topsoil on purple soil sloping farmlands in the Three Gorges reservoir area is weak. Both soil bund and horizontal ditch have good soil conservation effects on purple soil sloping farmlands, which play an important role in improving the capability of soil anti-erosion.更多还原