Geostatistics-based Evaluation of Main Nutrients in Qujing Tobacco Planting Soil

In order to investigate the spatial distribution of main nutrients in tobacco planting soil, 3650 soil samples were collected with GPS technique in Qujing. The overall characteristics and spatial variation of main nutrients in the soil were analyzed with classical statistics and geostatistics, and the spatial distribution maps of main nutrients were drawn with an ordinary Kriging interpolation method. The results indicated that:the main nutrients in Qujing tobacco planting soil obeyed normal or lognormal distribution, and distributed anisotropically. The spatial variance of available P in soil was mainly affected by random factors, while that of the other 7 nutrients was affected by both structural and random factors. The spatial distribution maps of main nutrients showed that:of the total samples, total K was seriously deficient throughout Qujing, the areas with low (12-18 g/kg) and very low (<12 g/kg) total K levels accounted for 42.76% and 44.16%, respectively; total P was at moderate level, the areas with low (0.8-1.2 g/kg) and very low (<0.8 g/kg) total P levels accounted for 37.76% and 9.29%, respectively; available P was at moderate level, the areas with low (10-20 g/kg) and very low (<10 g/kg) available P levels accounted for 22.09% and 0.32%, respectively. The pH of soil was suitable, the contents of total N, available N and available K in soil were extremely rich.