Digital soil mapping to enable classification of the salt-affected soils in desert agro-ecological zones

Abstract

Digital soil mapping is critical when quantifying the relationship between soil types and their associated bio-physical environments. Digital mapping of regional soils affected by salt is essential when monitoring the dynamics of soil salts and planning land development and reclamatation schemes. In this paper, an easy method for digitally mapping salt-affected soils is proposed. This method allows the construction of the quantitative lower categories of soil classification based on Chinese Soil Taxonomy by using a geostatistical method and GIS technology. The data and maps used in this study were collected during a soil survey of salt-affected desert agro-ecological zones in Karamay, Xinjiang Autonomous Region, China. The survey covers an area of 525 km 2 and includes 205 soil profiles. In addition, a classification and indicator system for the salt-affected soil in the region was established and 30 salt-affected soil types were identified. Three key soil classification indicators, viz. soil texture, texture stratification combination and total soil salinity, were selected to enable low-category soil classification. Furthermore, the information regarding climate, vegetation and topographic and geomorphologic features of the region was integrated into the analysis. A GIS-based regional digital soil classification map was then generated for three layers (0–30 cm, 30–60 cm, and 60–100 cm) after the observed soil salt distribution map and soil texture stratification maps were overlaid. This map would be used to draw up the strategies of the salt-affected soils improvement in desert. While compared with the conventional approaches, this new digital soil mapping method has the advantages of being prompt, quantitative, more objective, simpler and easier to update.