Evaluation of different interpolation methods for determination of spatial variability of some micronutrients in agricultural lands of Golestan province

In this research, the spatial distribution of Fe, Cu, Zn and Mn on agricultural lands of Golestan province were evaluated using different interpolation methods such as, Kriging, Inverse Distance Weighted, Local Polynomial, Inverse Multiquadric and Radial Basis Function. Thus, 505 soil samples were provided from fields during 2008 and micronutrients rates were measured for each sample. The performance criteria for evaluation the used method were Mean Absolute Error (MAE), Mean Bias Error (MBE) and Root Mean Square Error with the Cross Validation method. The results showed that Inverse Multiquadric and Kriging (Exponential and Spherical models) were the best methods to estimate Fe and Mn. Kriging and Local Polynomial were also found as the most suitable and unsuitable methods for estimating Cu, respectively. Inverse Distance Weighted method with power one, had the highest precision (MAE=0.304 and MBE=0.002) for estimation of Zinc rate in this area. Semivariograms nalysis indicated that Mn and Cu were best fitted to a spherical model.