Spatial distribution of some soil physico-chemical properties in agricultural soils of Isfahan province

Knowing about the spatial dependence of different soil characteristics in farms is important to achieve more production and better management. The aim of this study was to evaluate the spatial variability and frequency distribution of some physical and chemical properties, including pH, EC, organic carbon, phosphorus and potassium that can be used by plants, texture and cation exchangble capacity, within the various landforms of Isfahan province. The study was conducted on 118 soil samples. The spatial correlation of each variable with a specific semi-variable and the best fitting model for each variable were selected using GS+ version 9 software. Interpolation was done using normal Kriging, Cokriging, and Inverse Distance Weighting with powers of 1 to 3. The accuracy of the distribution maps of these variables were evaluated by the mean deviation of error (MBE) and the root mean square error (RMSE). The results of the geostatistical analysis showed that potassium, sand percentage and pH had strong spatial dependent and the other characteristics had moderate spatial dependent. The exponential model was the most accurate to predict phosphorus, EC, CEC, clay and silt variables while potassium, pH, sand and organic carbon percentage were best fitted with an sphericalmodel. Also, EC had the smallest effective range (14.86 km) and pH had the largest effective range (around 71 km). For potassium, pH and EC variables, the Inverse Distance Weighting with the power of 1 (IDW-1) and for other variables the normal kriging method were recognized as the best interpolation methods.