Comparison of interpolation methods for estimating pH and EC in agricultural fields of Golestan province (north of Iran)

In this research, the spatial distribution of Electrical Conductivity (EC) and pH on agricultural fields of Golestan province (north of Iran) were evaluated using some interpolation methods such as Kriging with different models, Inverse Distance Weighted (IDW) and Radial Basis Function (RBF). For this purpose, 505 soil samples were provided from fields during 2010. EC and pH rates were measured for each sample. The performance of methods was evaluated using by Mean Absolute Error (MAE), Mean Bias Error (MBE) and Root Mean Square Error (RMSE). The results showed that geostatistical methods had a higher accuracy compared to IDW and RBF. Kriging (Spherical model) was the best method to estimate pH, because it had the highest precision and lowest error. Exponential model-based kriging had the highest precision for estimation of soil EC in this area. Also, Radial Basis Function (TPS) model was the most unsuitable method for estimation of these soil properties. Semivariograms analysis indicated that pH and EC were best fitted to Spherical model