Vol. 2, Issue 11, Part A (2016)

Abstract
For practical soil management, indirect estimation of soil sodium adsorption ration (SAR, dimensionless) may be a good tool due to its important role in estimating of both the amount requirements of amendments and gypsum for soil reclamation. SAR is calculated from sodium, calcium and magnesium concentrations which are often determined with high costs. Therefore, developing of a simple tool to estimate SAR indirectly is more economical. Input data of the present study were collected from literature. The validation data were collected from actual laboratory soil analysis. Different regression models were developed to predict soil SAR based on soil electric conductivity (EC, dSm-1), soil pH (pH) and soil texture index (STI, dimensionless). The best regression model for estimating SAR was selected based on higher coefficient of determination (R2), lower both root mean square error (RMSE) and mean absolute error (MAE). The best regression model had the following form: