Spatial Variability of Soil Properties in a Long-Term Tobacco Plantation in Central China

Spatial variability in soil properties has long been observed within uniformly managed fields. Understanding the spatial characteristics of soil properties would be helpful in the development of site-specific management. Uniform management results in overapplication in areas with high nutrient levels and underapplication in areas with low nutrient levels. The objective of this study was to quantify the degree of spatial variability of soil properties. This is important to tobacco quality across flue-cured tobacco (Nicotiana tabacum) plantation fields. Fourteen soil properties were analyzed by geostatistical techniques. Soil organic matter (OM) had significantly positive correlations with active soil OM, total N (TN), available N, available phosphorus, available potassium, Cu, Fe, and Mn. Soil TN, Zn, cation exchange capacity, and silt showed strong spatial dependence, with nugget-sill ratios ranging from 3.39% to 23.43%. Other soil properties showed moderate dependence, with nugget-sill ratios of 30.87% to 49.99%. Spatial dependence ranged from 34.3 m (Zn) to 376.3 m (Mn). The OM contour map showed highest similarity with that of TN. Variography and kriging are useful tools for soil-sampling strategies and variable-rate application in site-specific farming.