Abstract
The purpose of this paper was to study the spatial characteristics and possible influencing factors of farmland soil texture and salt content in the Syr Darya River Basin. Data on the soil grain size and salt content were collected at 56 sampling sites in the southern part of the Shardara Reservoir and the left bank of the Syr Darya River irrigation area. With the methods of local spatial statistics (Getis-Ord Gi* and Moran’s I), the hotspots of soil salinity and grain size in the study area were revealed, and along with the use of correlation analysis, the possible factors affecting soil salt distribution were discussed. Among the 56 soil sampling sites, sandy loam, loamy loam, and chalky loam accounted for 20%, 50%, and 30%, respectively, and mildly, moderately, and severely saline soils accounted for 80.36%, 14.28%, and 5.36%, respectively. There was statistically significant spatial autocorrelation between sand, silt, and clay content in the soils, but the spatial autocorrelation for salt content was weak. The results show that high and high-cluster areas (hotspots) with statistically significant salt content are mainly distributed in the northwest of the study area and that the hotspot distribution of salt content is mainly affected by topography (altitude), but the effect of soil texture on salt content is not significant. The control of soil salinity should prioritize low-altitude areas, especially in the northwestern region. The results are of great significance for the regulation and control of soil salinity and the sustainable utilization of soil in arid Central Asia.
Highlights
Soil is a complex non-homogeneous part of terrestrial ecosystems that acts as a hub connecting other environmental elements, but is a central link between inorganic and biotic combinations, and is formed mainly from soil-forming parent materials through a series of physical, chemical, and biological processes [1,2]
Existing studies have shown that soil texture has a close relationship with salt content and pH [7], especially its accumulation and spatial distribution pattern in the surface layer [8]
The average content of medium silt with grain sizes of 0.01–0.005 mm accounted for only 6.72%, and the content of fine silt with grain sizes of 0.055–0.001 mm accounted for 10.98%
Summary
Soil is a complex non-homogeneous part of terrestrial ecosystems that acts as a hub connecting other environmental elements, but is a central link between inorganic and biotic combinations, and is formed mainly from soil-forming parent materials through a series of physical, chemical, and biological processes [1,2]. The agricultural irrigated arable land of Kazakhstan, a republic of the former Soviet Union, is mainly distributed on both banks of the Syr Darya, one of the major rivers feeding the Aral Sea [18]. While current studies of the soils of the Syr Darya River Basin have mainly focused on the inversion of soil moisture content based on multi-source remotely sensed data [19], the distribution characteristics of heavy metals in the soil [20,21] and assessments by soil conservation services [22] have only found soil salinity mapping with satellite images [23]. The texture and salinity characteristics and spatial heterogeneity of agricultural soils in the Syr Darya River Basin of Kazakhstan have not been studied yet
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