Spatial Variability of Soil Particle Size Distribution and Fractal Features in Water-Wind Erosion Crisscross Region on the Loess Plateau of China

The spatial variability of soil particle size distribution and fractal dimension (D) values play important roles in both agriculture and environment. They impact soil texture, soil quality, and soil erosion. A grid sampling design was used to collect 325 topsoil (0-20 cm) samples from the Daye watershed (0.54 km2) in the water-wind erosion crisscross region of the Loess Plateau of China. Classical and geostatistical methods were combined to determine the spatial variability of soil particle size distribution and D values. The D values in the research area ranged from 1.37 to 2.66. There was a significant sigmoidal correlation between D values and the contents of clay, silt, and sand fractions. The D values of four different land uses could be arranged in the following order: woodland > farmland > grassland > shrubland. Values of D had moderate spatial autocorrelation, and clay, silt, and sand contents had strong spatial autocorrelation in the watershed landscape. The interpolation maps showed that D values could be an efficient way to evaluate the degree of soil desertification and degradation.