Particle size distribution of soils (0–500 cm) in the Loess Plateau, China

• Clay, silt, and sand content for various layers had moderate spatial variations.
• Soils were overall sandy in the north and clayey in the south.
• The variation of soil textures was uneven with the increase of latitude.
• Spatial variability of clay content was similar to fractal dimensions.

To investigate the spatial variability of soil particle size distribution (PSD) in the Loess Plateau (LP) region of China, 2673 disturbed soil samples were collected in the 243 soil profiles (0–500 cm) across the typical loess zone. The PSD of soil samples were determined using the laser diffraction technique and the regional spatial distribution patterns of PSD were analyzed through classical statistical and geo-statistical methods. The results showed that silt loam was the dominant soil texture (92.6%) at the 0–500 cm soil layer. Sand, silt and clay contents varied slightly with increasing soil depth, suggesting that soil texture was almost homogeneous across the soil profile. Soils were overall sandy in the north and clayey in the south, but soil texture variation uneven with increasing latitude. PSD pattern across the typical LP region depicted latitudinal zonality. Fractal analysis showed a strong relationship between fractal dimension (D) and clay content (R2 = 0.98), demonstrating that D was controlled by the clay content rather than the coarse particles at the regional scale. The limited changes of PSD in the soil profile and the moderate variation of soil texture across the LP will provide a reference to regional scale hydrological, erosion and ecological models in the Loess Plateau of China.