Field scale mapping of soil salinity on spatial interpolation techniques, case study: Khorat Basin, Nakhon Ratchasima Province, Thailand

Khorat Basin study area, Nakhon Ratchasima Province (Northeastern of Thailand) was separated by the topographical characteristics of plain, low terrace, and middle terrace. The soils physical and chemical properties were analyzed. The Electrical Conductivity (EC_e) was conducted to interpolate the following methods of GIS: Completely Regularized Spline method, Spline with tension method, Inverse Distance Weighting method, Ordinary Kriging method, Simple Kriging method, and Disjunctive Kriging method. Also, the Mean Absolute Percent Error (MAPE) method was applied to compare the interpolation methods and select the most suitable interpolation method for soil salinity. The results indicate Completely Regularized Spline is the most suitable interpolation method for soil salinity of all study sites, because it has the minimum errors when compared to the others. The percent of errors ware 36.90, 24.25, and 44.79 in plain, low terrace, and middle terrace, respectively. Likewise, the production of the soil salinity map was interpolated by Completely Regularized Spline method in the study area.