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土壤颗粒分布特征作为土壤物理性质的基本组成部分,对土壤中水分运移、溶质迁移等土壤物理过程有着重要的作用,同时也是影响土壤侵蚀过程的主要因素之一。紫色土作为一种侵蚀型高生产力的岩性土壤,当其分布于三峡库区大于25°陡坡地时,成为了该地区水土流失的重要物质来源。为了分析降雨强度对紫色土陡坡地土壤颗粒分布空间变异的影响,该文研究了25°径流小区在不同人工模拟降雨条件下(0.285,0.978,1.737mm/min)紫色土土壤机械组成和团聚体稳定性的空间变异特征,结果表明:(1)25°陡坡地土壤机械组成在各个降雨强度下,空间分布特征都表现为小区上坡位置粘粒和粉粒含量减少,砂粒含量增加;中坡粘粒及粉粒含量增加,砂粒含量减少;下坡粘粒及砂粒含量增加,粉粒含量减少的特征。但是土壤机械组成各组分随雨强的变化,各自的含量表现出不同程度的增加或减少幅度。(2)陡坡地中>0.25mm水稳性土壤团聚体含量(WAS0.25)、>2mm和>0.25mm团聚体分散度(P2、P0.25)的变化特征与降雨强度有密切关系,但是其空间差异性变化不明显。在不同降雨强度影响下WAS0.25的减小幅度在6.7%～16.87%中变化,而P2和P0.25各自的增幅则分别达到了1.94%～5.45%和4.46%～15.45%。通过对陡坡地径流小区紫色土土壤颗粒分布在降雨作用下的空间变异特征研究,为坡面土壤颗粒侵蚀-迁移-沉积这一微观过程的宏观反映提供了一定的理论依据,同时也为三峡库区紫色土25°陡坡地水土流失的防治提供相应的理论基础。
As a basic component of soil physical properties, soil particle distribution has an important role in soil physical processes such as water transport and solute transport, and is also one of the main factors affecting soil erosion process. Purple soil, as an erodible and productive lithology soil, is an important source of soil and water loss in the area when distributed over more than 25 ° steep slopes in the Three Gorges Reservoir area. In order to analyze the effect of rainfall intensity on the spatial variability of soil particle distribution in steep slopes of purple soil, this paper studied the effects of rainfall intensity on the spatial variability of soil particle distribution on purple soil steep slopes under different artificial simulated rainfall conditions (0.285, 0.978 and 1.377 mm / min) The results showed as follows: (1) The spatial distribution of soil mechanical composition at steep slopes with 25 ° steep slopes showed that the clay and silt content decreased and the sand content increased at uphill slope. The mid-slope Clay and silt content increased, the sand content decreased; downhill clay and sand content increased, reduced the content of grain. However, the composition of soil mechanical components with rainfall intensity changes, their content showed varying degrees of increase or decrease. (2) The variation characteristics of the aggregate dispersions (> 0.25 mm), the water dispersible aggregates (WAS0.25),> 2 mm and> 0.25 mm in steep slopes are closely related to rainfall intensity The spatial variation is not obvious. Under the influence of different rainfall intensities, the decrease of WAS0.25 varied from 6.7% to 16.87%, while that of P2 and P0.25 respectively increased from 1.94% to 5.45% and from 4.46% to 15.45%. By studying the spatial variability of soil particle distribution of purple soil in steep-slope runoff plot under rainfall, this study provides a theoretical basis for macroscopic reflection of microscopic process of soil particle erosion-migration-sediment on slopeland, The corresponding theoretical basis is provided for the prevention and cure of soil erosion on the 25 ° steep slope in purple soil area.