Sodium-Calcium Exchange Equilibria in Some Salt-Affected Soils

Exchangeable sodium ratio (ESR)-sodium adsorption ratio (SAR) relationship was tested for three saline-sodic soils. Determination of exchange isotherms and calculation of the parameters for each soil separately in relation to their exchange behaviour was done. Equilibrium sodium adsorption ratios (SAR_e) obtained as intercept of ESR-SAR plot at SAR axis for the three soils were much lower than the SAR values calculated from the composition of saturation extract. Steeper slope of ESR-SAR exchange isotherm for Faganmajra soil (8.75×10⁻²) as compared to Kheru (4.125×l0⁻²) and Domeli (4.0 × 10⁻²) soils indicated that the former soil has a relatively high affinity for Na.