喀斯特不同侵蚀场地土壤颗粒分布及可蚀性特征

选取西南喀斯特最为典型的坡地、洼地和落水洞为研究单元,采用野外调查采样与室内试验相结合的方法,研究坡地、洼地和落水洞土壤颗粒的分布规律和土壤可侵蚀性特征。结果表明:土壤颗粒的质量分数分布,坡地为砂粒(42.25%)>粉粒(36.33%)>黏粒(21.42%);洼地为粉粒(51.80%)>砂粒(32.61%)>黏粒(15.59%);落水洞为粉粒(51.65%)>砂粒(31.67%)>黏粒(16.68%),坡地以砂粒为主,洼地和落水洞以粉粒为主。土壤可侵蚀性K值变化范围:坡地为0.07~0.22,洼地和落水洞分别为0.26~0.33和0.25~0.32,坡地土壤抗侵蚀能力强于洼地和落水洞。土壤分形维数与砂粒含量呈负相关,与粉粒含量呈正相关,与黏粒含量呈显著正相关。土壤可侵蚀性K值与砂粒和黏粒含量呈负相关,与粉粒含量呈显著正相关。土壤侵蚀沉积易形成质地较细,结构良好的土壤,但形成的土壤抗侵蚀能力较弱,易发生二次水土流失。

Particle size distribution and erodibility of soils under different erosion sites in karst

To study the distribution of soil particle size and soil erodibility in karst slopes,depressions and dolines,the most typical example of these karst formations in southwest China was selected as the research unit;field investigations and sampling along with laboratory testing was performed.The results showed that the distribution of soil particles decreased in the slope as sand(42.25%)>silt(36.33%)>clay(21.42%);in the depressions as silt(51.80%)>sand(32.61%)>clay(15.59%);and in the dolines as silt(51.65%)>sand(31.67%)>clay(16.68%).This indicated that sand played a dominant role in the soil particles of sloping land,with silt providing the dominant influence in depressions and dolines.The change range of soil erodibility(K value)was 0.07-0.22 in the slopes,with the corresponding values in the depressions and dolines in the ranges 0.26-0.33 and 0.25-0.32,respectively.The erosion resistance of slope soil is greater than that of the depressions and dolines.The value of the soil fractal dimension was negatively correlated with sand content,positively correlated with silt content,and positively correlated with clay content.K value was negatively correlated with sand content and clay content,and significantly positively correlated with silt content.Soil erosion and deposition tend to form soil with fine texture and good structure;however,the soil erosion resistance of the formed soil is weak,and secondary water loss and soil erosion commonly occur.