红壤丘陵区坡地土壤颗粒组成的空间分布特征研究

通过分析红壤丘陵区农田坡面14个0~100 cm剖面的土壤颗粒组成,结合研究区土壤侵蚀等相关资料,拟阐明坡面尺度土壤砂粒、粉粒和黏粒含量的空间分布特征,揭示自然条件下土壤颗粒组成在水平和垂直方向上的分布规律。结果表明:坡面尺度土壤砂粒、粉粒和黏粒均呈现出中等的空间异质性,变异系数分别介于17.6%~23.2%、10.7%~15.8%和13.5%~17.0%。由于粗颗粒的沉积,花生地和橘园地均表现出坡下的砂粒含量显著高于坡上和坡中(P0.05),黏粒含量坡下显著低于其他坡位(P0.05);由于黏粒更容易随入渗过程向深层运动,两种植被类型均表现出土壤砂粒含量随深度增加而降低(P0.05)、黏粒含量随深度增加而增加的趋势(P0.05)。无论在水平方向还是垂直方向上,粉粒含量均无明显变化规律(P0.05)。砂粒含量随坡位和土壤深度的变化程度均大于粉粒和黏粒。植被类型及相应的耕作制度影响土壤颗粒的分布,土壤砂粒在水平方向上的运动在花生地表现得强于橘园地;橘园地土壤黏粒含量在垂直方向上的迁移速率大于花生地,而对粉粒含量的分布规律影响不大。

Spatial Distribution Characteristics of Soil Particle Composition of Slope Land Red Soil Region, China

The soil particle composition of 14 soil profiles(0 – 100 cm)in red soil hilly region was investigated along a slope. The spatial distribution of soil particle composition in both horizontal and vertical direction was analyzed combining with the related data, e.g. soil erosion. The objectives of the present study were to clarify the spatial distribution characteristics of soil sand, soil silt and soil clay under the slope scale, and to reveal the migration law of them in two directions under natural conditions. Results showed that sand, silt and clay contents exhibited moderate spatial heterogeneity, with coefficient of variation changing between 17.6% and 23.2%, 10.7% and 18.8%, 13.5% and 17.0%, respectively. Due to the deposition of coarse particles, higher sand content was observed in bottom slope than top and middle slope in both peanut and citrus orchard land (P < 0.05). The clay content in bottom slop was, however, significantly lower than other slop position (P < 0.05). Soil sand content decreased whereas the clay content increased with increasing soil depth (P < 0.05) for both vegetation types, mainly due to the movement of more clay particles with the infiltration process of soil water. The silt content did not change significantly in both horizontal and vertical directions. Sand content had stronger variation among slope positions and soil depths than silt and clay contents. In addition, the distribution of soil particles were also affected by vegetation types and cropping systems. The migration of soil sand along the slope was more significant in peanut land than in citrus orchard. The migration rate of clay in the vertical direction was stronger for citrus land than peanut land. However, vegetation types and cropping systems had little effects on the distribution of soil silt content.