Abstract: Geostatistics, correction analysis, regression analysis and GIS technology were used to clarify the spatial variations of soil available microelements (Fe, Mn, Cu, Zn and B) and to explore their influencing factors in different geological formation units in the source region of the Danjiang River of the Middle Route of China’s South-to-North Water Transfer Project. The results showed that the average contents of soil available Fe, Mn, Cu, Zn and B were 45.51, 42.39, 1.26, 3.34 and 0.39 mg·kg^-1, respectively. Among them, the contents of available Fe, Mn and Zn were above the rich levels, available Cu reached the medium level, while available B was at the poor level. According to the results of semi-variance analysis, soil available Zn exhibited strong spatial variability (CV=130.4%) in different geological formations, influenced by structural factors. Soil available Mn, B, Fe and Cu all showed moderate spatial variabilities (CV=52.8%-94.2%), which were mainly affected by both structural and random factors. Soil available N, P, K and organic matter contents were positively correlated with soil available microelements, while soil pH was negatively correlated with available Mn and Fe, but not significantly correlated with available B, Cu and Zn. Generally, the geological formation has a strong explanatory power on the spatial variation of soil available microelements, which provides a reliable reference for the utilization and management of land resources in different regions based on geological formations.

Key words: geological formation, soil available microelement, spatial variability, influencing factor, source region of the Danjiang River