Mapping of Soil Salinity Using Geostatistic and Electromagnetic Induction Methods in Ardakan

Precise mapping of the spatial distribution of salt-affected soils is prerequisite for effective management of these soils. This study was carried out for mapping soil salinity of 78000 hectares of Ardakan soils (0-30 and 0-100 cm) using 151soil samples which were taken based on hyper cube method. The secondary variables used in co-kriging method were ETM data، terrain analysis and EM38 readings. The best model was selected by means of cross validation and error evaluation methods، such as RMSE and ME methods. Results showed that co-kriging method with EM38 data as a secondary variable was the best method for prediction of soil salinity (69. 1، 30. 55، 48. 8 and 20. 41، respectively). Results recommended EM38 as secondary data for mapping soil salinity. Additionally، results showed the largest amount of soil salinity in the north of the area and the smallest values in the areas with more elevation. The concavely shaped plain could help to move soluble salts toward the north of area in which the soils with highest electrical conductivity are found.