Geostatistical analysis of variations in soil salinity in a typical irrigation area in Xinjiang, northwest China

Characterizing spatial and temporal variability of soil salinity is tremendously important for a variety of agronomic and environmental concerns in arid irrigation areas.This paper reviews the characteristics and spatial and temporal variations of soil salinization in the Ili River Irrigation Area by applying a geostatistical approach.Results showed that:(1) the soil salinity varied widely,with maximum value of 28.10 g/kg and minimum value of 0.10 g/kg,and was distributed mainly at the surface soil layer.Anions were mainly SO₄^2- and Cl^-,while cations were mainly Na⁺ and Ca²⁺;(2) the abundance of salinity of the root zone soil layer for different land use types was in the following order:grassland >cropland >forestland. The abundance of salinity of root zone soil layers for different periods was in the following order:March >June >September;(3) the spherical model was the most suitable variogram model to describe the salinity of the 0-3 cm and 3-20 cm soil layers in March and June,and the 3-20 cm soil layer in September,while the exponential model was the most suitable variogram model to describe the salinity of the 0-3 cm soil layer in September.Relatively strong spatial and temporal structure existed for soil salinity due to lower nugget effects;and(4) the maps of kriged soil salinity showed that higher soil salinity was distributed in the central parts of the study area and lower soil salinity was distributed in the marginal parts. Soil salinity tended to increase from the marginal parts to the central parts across the study area.Applying the kriging method is very helpful in detecting the problematic areas and is a good tool for soil resources management.Managing efforts on the appropriate use of soil and water resources in such areas is very important for sustainable agriculture,and more attention should be paid to these areas to prevent future problems.