紫色土流失土壤的颗粒特征及影响因素

Particle Characteristics and Influencing Factors of Eroded Purple Soil

土壤可蚀性是影响坡面水蚀过程的内在因素,与土壤质地,土壤有机质等理化性质密切相关。本研究利用田间人工模拟降雨观测资料,分析了侵蚀过程中流失土壤颗粒组成的变化。结果表明:(1)在次降雨过程中,流失土壤颗粒组成不断变化。随着降雨的进行,细砂含量逐步增加,而粉粒含量基本不变,黏粒含量逐渐减小;(2)雨强是影响流失土壤颗粒组成的重要因素。随雨强增加,细砂含量呈逐步增大的趋势,而粉粒与黏粒含量均逐步下降;(3)坡度对流失土壤颗粒组成影响比较复杂。随坡度增加,细砂含量先增大后减小,粉粒与黏粒含量先减小后增大;在20°坡度时,细砂含量最大,粉粒与黏粒含量最小。

Soil erodibility is the intrinsic factor which has effect on water erosion on slope and is related to soil texture, soil organic matter, and other soil properties. Sediment particle is analyzed by using plot data from rainfall simulation experiments. Results show that （1） during rainfall, particle composition of sediment changes with time. Sand content increases, silt content keeps constant, and clay content decreases. （2） Rainfall intensity is the important factor to the particle composition of sediment. With rain intensity increasing, sand content increases and slit and clay contents are reduced. （3） The effect of slope gradient on sedi- ment is complicated. When slope becomes steeper, sand content increases first and then decreases, whereas silt and clay contents decrease first and then increase. When slope gradient is 20°, sand content reaches the maximum and slit and clay contents, the minimum.