SPATIAL VARIABILITY OF SOIL MICROELEMENTS IN THE MIDDLE AND LOWER REACHES OF HEIHE RIVER BASIN, NORTHWEST CHINA

To understand the spatial variability of soil available microelements is an important precondition for rational fertilization and soil management. 240 soil samples were collected and the location of each plot was recorded by a global positioning system (GPS). Geostatistics and Geographic Information System (GIS) techniques were also applied to characterize the spatial variability of available microelements. The results showed that available Cu, Ni and Fe accorded with exponential model, available Zn and Co accorded with Gaussian model, and available Mn accorded with spherical model. Available Cu, Zn, Ni, Fe and Co had moderate spatial dependence, and available Mn had a strong spatial dependence. The spatial distribution of available Cu, Zn, Ni, Fe and Co were significantly correlated with the soil-forming factors and human activities such as parent materials, application of fertilizers, soil management and cultivation, the spatial distribution of available Mn was attributed to soil-forming factors strongly.