Spatial variability of equivalent calcium carbonate using geostatistic methods in soils of Achachi region Miyaneh, Iran

Structural changes, including gradual and identified variations in soil properties is a function of physiography, geomorphology and a set of interactions of soil forming factors. Even after classification or zoning of soil properties and displaying them in the form of map units, the units are not completely homogeneous, and show significant spatial variations. The aim of the study was to evaluate the effectiveness of a number of common methods of interpolation to estimate and delineate one of the qualitative and impressive characteristics of the soils, that is, calcium carbonate equivalent in the farms located in Aidoghmoush dam downstream in Miyaneh county. A total of 62 topsoil samples from a depth of 0-30 cm was randomly collected and analyzed in laboratory. After checking the normality of the data, isotropic experimental variogram was calculated and variography results were analyzed. Geostatistic methods of Kriging and inverse distance weighted were used for interpolating and zoning of soil lime. Exponential, Gaussian and spherical models were fitted to experimental variograms. For evaluation of interpolation methods cross validation, mean absolute error, mean bias error, root mean square error and coefficient of determination were used. The results showed that in lime estimating and changes, Kriging method was superior than inverse distance method because of the 1.86% mean absolute error as well as the exponential model than other models met stronger spatial structure. So the results of this study with regard to the best method of interpolation used in draw the calcium carbonate zoning map, it can be suggested that the use of geostatistics to efficient use of calcareous soils in studied area to achieve the precise management of these soils.