干旱区生态环境知识资源中心

Soil quality assessment is tremendously important for agronomic and environmental concern. The objective of this study was to spatially evaluate soil salinity and its geochemistry at regional scale.

A soil quality assessment study was conducted over a 1,000 km(2) field in Datong basin, northern China via collecting and determining 163 topsoil samples. A combined approach of statistical methods and hydrochemical tools was applied for a comprehensive analysis in this study.

In the study area, the nonsaline lands (total dissolved solids (TDS) < 0.08 %, Ca-HCO3 type soils) that are located in the pluvial plains consist of coarse-medium sands and deep unsaturated zone (depth > 10 m). The slightly (0.08 % < TDS < 0.2 %, Ca-Na-HCO3-NO3 type soils) and the moderately (0.2 % < TDS < 1 %, Ca-Na-SO4 type soils) saline lands are located in the alluvial plains and the central basin composed of fine sediments like fine sands, loams and silts, and intermediately deep unsaturated zone (depth 2-10 m). By contrast, due to irrigation, the very (1 % < TDS < 2 %) and the extremely (TDS > 2 %) saline areas with Na-SO4/Na-Cl type soils are locally found in some desolate lands comprised of silty clays and shallow unsaturated zone (depth < 2 m) in the central basin.

As a result of water-rock/sediments interactions, effects of landscapes and anthropogenic activities, soil salinity is characterized by strong spatial variability in Datong. The new insights into the basin-scale distribution pattern of soil salinity in inland basins of silicate terrain under arid climatic conditions should be applicable in other similar regions of the world.