Mapping of Soil Salinity and Sodicity Hazard Using Indicator Krijing in Ghorveh, Kurdistan Province

In the recent decades, application of geostatistic for mapping salinity and sodicity of soil and investigation of their changes has developed. The purpose of this study is to use Indicator Krijing to make probability maps of soil salinity and sodicity. In order to do this, in 178 points of the study area, 356 soil samples from two depths, i.e. 0-30 and 30-60 cm, were taken in Ghorveh soils, Kurdistan Province, using hypercube method. Then, electrical conductivity, pH, Na, Ca, Mg, and Sodium Adsorption Ratio characteristics were measured. Using Indicator Krijing, probability maps of soil salinity and sodicity were prepared for both depths based on two threshold indices of 4 dS/m for salinity and 13 (mmoll-1)0.5 for SAR. Results showed that probability maps of 0-30 cm depth for soil salinity and sodicity, respectively, with 0.53 and 0.94 Kappa index, had moderate and excellent accuracy levels, while in 30-60 cm depth, with 0.64 and 0.8 Kappa index, respectively, had good and excellent accuracy levels. Central part of the area had higher probability of salinity and sodicity compared to the other parts. This part of the area had lowland physiography and somewhat unsuitable water table near the soil surface.