黄土丘陵小流域土壤物理性质的 空间变异

黄土丘陵小流域土壤物理性质在景观尺度上的空间变异以质地、容重和饱和含水量最小，稳定入渗率最大，团稳性与粘结力居中，不同土地利用类型之间诸项物理性质都存在显著差异，土壤质地以林地的砂粒含量显著偏低但粉粒含量显著高于其它土地利用类型，休闲地的粉粒含量显著较低；容重以林地显著偏大，耕地较小；饱和含水量以灌木地较大，林地显著偏低，土壤团稳性以林地显著偏高，耕地显著偏低；土壤粘结力以灌木地，林地，荒地和休闲地显著较强，耕地显著较弱；稳定入渗率以灌木地显著较高，间作地显著较低，就坡形来说，垂直与水平凹形坡的砂粒含量都显著较低而粉粒含量比较高，相反直形坡的砂粒比较高而粉粒含量显著较低；饱和含水量与稳定入渗率都是以垂直直形坡较高，垂直凹形坡则较低，就坡向而言，偏东坡的土壤粘结力显著低于偏西坡；偏北坡土壤质地比偏南坡粘性强，但稳定入渗率低，稳定入渗率还随坡度的增大而增高，随着海拔的升高，土壤砂粒含量与稳定入渗率增高，而粘粒含量与团稳性呈降低趋势。

Variability of the Soil Physical Properties on the Loess Plateau

The degree of spatial variability of the soil physical properties and the ability of environmental attributes to predict that variability were studied in Da Nangou catchment (3.5 km2) on the Loess Plateau, China. The soil physical properties including soil texture (sand, silt, clay), bulk density, saturated soil moisture content, aggregate stability, soil cohesion, stable infiltration rate were measured at 111 plots across the catchment. It is found that the spatial variation is small for soil texture, bulk density and saturated soil moisture content, moderate for aggregate stability and cohesion, and great for stable infiltration. The spatial distribution of the soil physical properties is due to the joint-influence of land use and topography, and the dominant factors differ for different soil physical properties. There is significant difference in the soil physical properties between different land use types as determined by the correlation analysis. The sand content shows the lowest value while the silt content exhibits the highest values on the woodland, and the silt content is lower for the fallow land than the other land use types. The bulk density exhibits the greatest values for the woodland while it is the lowest for the cropland. For the saturated soil moisture content, it is the greatest for the shrub land while it is the lowest for the woodland. The woodland also is the strongest in the aggregate stability, while the cropland is the weakest. The soil cohesion shows higher values for the shrub land, woodland, wasteland and the fallow land, but it displays a lower value for the cropland. The shrub land is the greatest in the stable infiltration rate, while the intercropping land is the lowest. Based on the correlation analysis, it is indicated that a significant correlation exists between the soil physical properties and the terrain indices. The sand content is lower and the silt content is higher on the concave slope than the other surface types, however, the straight slope shows an opposite picture.