Spatial heterogeneity of soil salinization and its influencing factors in the typical region of the Mu Us Desert-Loess Plateau transitional zone, Northwest China

Abstract

Studies on the spatial heterogeneity of saline soil in the Mu Us Desert-Loess Plateau transition zone are meaningful for understanding the mechanisms of land desertification. Taking the Mu Us Desert-Loess Plateau transition zone as the study subject, its spatial heterogeneity of pH, electrical conductivity (EC) and total salt content were analyzed by using on-site sampling followed with indoor analysis, classical statistical and geostatistical analysis. The results indicated that: 1) The average values of pH, EC and total salt content were 8.44, 5.13 mS·cm-1 and 21.66 g·kg-1, respectively, and the coefficient of variation ranged from 6.9% to 73.3%. The pH was weakly variable, while EC and total salt content were moderately variable. 2) Results of semivariogram analysis showed that the most fitting model for spatial variability of all three indexes was spherical model. The C0/(C0+C) ratios of three indexes ranged from 8.6% to 14.3%, which suggested the spatial variability of all indexes had a strong spatial autocorrelation, and the structural factors played a more important role. The variation range decreased in order of pH <total salt < EC. The Kriging interpolation showed that pH, EC and total salt content distributed in a striped pattern with good continuity. The pH value increased with increasing terrain slope, while EC and total salt content decreased. 3) In terms of vertical distribution, the salt aggregated on surface in the area with severe salinization. In the area with light salinization, the vertical distribution of salinity was firstly decreased and then increased. In general, the heterogeneity of soil salinization in the Mu Us Desert-Loess Plateau transition zone was influenced by climate, landscape, plant distribution, especially affected by geological conditions, topography and hydrogeological conditions. This study provided a theoretical basis for future land engineering and ecosystem restoration programs.