Investigation of Interpolation Methods for Determination of Organic Carbon and Nitrogen Spatial Distribution in Lanjanat Region in Isfahan Province

This research was carried out to compare the methods of determining the spatial distribution of soil organic carbon and nitrogen on 50,000 hectares of Lenjanat area in Isfahan province, central Iran. The spatial distribution of elements was determined by Ordinary Kriging, Inverse Distance Weighting, and Spline Tension interpolation methods. The results indicated that there was an average spatial structure in the variables. Empirical variograms showed that there was no specific anisotropy process for variables. In order to determine the accuracy of the estimation of interpolation methods, the standard data (150 data for each variable) and statistical criteria including Mean Estimation Error (MEE), Mean Square Estimation Error (MSEE), Root Mean Square Error (RMSE), relative Error (Er) and Pearson correlation coefficient (r) were used. Despite the high spatial variability of the parameters, the results indicate the accuracy of the estimated values by means of interpolation methods. For soil organic carbon in the study area, Ordinary Kriging and Spline Tension interpolation methods with lower error (MEE= 0.007, MSEE= 0.09, RMSE= 0.3, Er= 0.32 and r= 0.73) were more accurate compared with the Inverse Distance Weighting interpolation method (MEE= 0.009, MSEE= 0.096, RMSE= 0.31, Er= 0.31 and r= 0.71). Also, Ordinary Kriging and Inverse Distance Weighting interpolation methods with a lower error (MEE= 0.003, MSEE= 0.0006, RMSE= 0.025, Er= 0.296 and r= 0.8), compared with Spline Tension interpolation method (MEE= 0.0017, MSEE= 0.0007, RMSE= 0.026, Er= 0.301 and r= 0.78) had more accurate estimation of soil nitrogen in the region.