Evaluating inverse distance weighting and kriging methods in estimation of some physical and chemical properties of soil in Qazvin Plain

Abstract

Today, the presence of accurate information about variability of soil properties beenconsidered more than ever to apply this information in economic modeling,environmental predictions, accurate farming and natural resources management. Thepresent research was conducted in some lands of Qazvin plain to study variability ofsome chemical and physical properties of soil by sampling 62 observational points indepth of 20 cm above soil surface. Initial statistical study of data indicated that thestudied properties follow normal distribution in the region. Spatial variations of thestudied properties showed that spherical model was the best fitted model tosemivariogramin other properties than silt percent and bulk densityand total porosity.The highest radius for the studied properties was 21100 m related to bulk density, totalporosity and electric conductivity and pH. Spatial dependence class was observedmedium to strong in all physcial and chemcial properties. To validate intrapolationmethods, three indices of evaluation, R2, MBE, MAE which indicate accuracy of each ofthe intrapolation methods were used and results showed that the studied properties hadspatial structure, their impact range had good variability and kriging estimator bettercan show variability of the studied properties in the region in comparison to IDWmethod. At the end, considering the best interpolation method, spatial variability map ofeach of the properties was prepared in ArcGIS software.