Spatial Variability and Influencing Factors of Available Microelements in Tobacco Growing Soils in Qujing

In order to investigate the spatial distribution and influencing factors of available microelements in tobacco growing soil, 2088 soil samples were collected from Qujing tobacco growing areas by adopting GPS technology, the general characteristics and spatial variability of available microelements in the soil samples were analyzed, and the spatial distribution of available microelements was mapped with ordinary Kriging interpolation. The factors affecting available microelements were also studied. The results indicated that all the available microelements were of moderate variability and distributed anisotropically. The spatial variance of available B was mainly affected by random factors, while that of other available microelements was affected by both structural and random factors. Available B was extremely deficient throughout Qujing, the areas with very low (<0.25 mg/kg) and low (0.25-0.50 mg/kg) available B accounted for 7.74% and 68.20%, respectively; available Zn was above moderate, the areas with low (<1.5 mg/kg) available Zn only accounted for 1.32%; the contents of available Cu, available Fe and available Mn were very rich; the contents of available Mo presented large regional differences, the areas lacking of available Mo accounted for 28.38%. Altitude, soil type, soil pH, organic fertilizer input and preceding crop were main factors affecting the available microelements in tobacco growing soil.