Soil particle size distribution and its relationship with soil water and salt under mulched drip irrigation in Xinjiang of China

Soil particle size distribution (PSD), one of the most important soil physical attributes, is of great importance to soil water movement, soil erosion and soil solute migration. In this study, the soil PSD of 563 soil samples from the mulched drip irrigated cotton fields in Xinjiang of China were measured by laser diffraction particle size analyzer. The soil PSD characteristics and its relations with soil water and salt were studied by using the combined methods of textural triangle, fractal and multifractal analysis. The results showed very low clay content (about 1.52%) while really high sand content of the studied soil, and a complex shape of bimodal or unimodal of soil PSD. The results also showed that the two indices, i.e., standard deviation and the peak value of soil particle relative volumes, were good indicators of soil PSD and thus had good relations with fractal and multifractal characteristics. The correlative analysis further indicated that the mulched drip irrigation had a significant impact on the distribution of the soil salt, while this impact withered for the deeper soil layer. The soil texture feature was found to dominate soil water and salt distribution, especially the surface soil salt content and the deep soil water content.