Rhoades (1968) model for predicting sodic hazard from irrigation water has been tested for an alluvial soil of Karnal (Haryana), taken in columns and lysimeters. Use of weathering coefficient (Y) value of 0.75 for waters of pHc<7.50 and a value of 0.80 for waters of pHe>7.50 in the above model gave a good quantitative estimate of the SARdw in the laboratory soil columns. While SAR of the saturation extract of soil of the tower root zone in lysimeters agreed well with the calculated SAR of the drainage water leaving the root zone during monsoon leaching, the upper root zone values were slightly lower than the calculated ones.
Sodic waters, sodium adsorption ratio, weathering coefficient, testing of model
