Effect of Dissolution and Precipitation of Calcium Carbonate on the Adsorption of Sodium by Soils in Saline Waters

Effect of 15 quality waters was studied on pure lime and 3 calcareous soils to determine, (i) the amount of release of Ca+Mg from the soil, (ii) the critical pH_c value which influences the dissolution or precipitation of calcium carbonate and (iii) the changes in the development of ESP of soils. Calcium carbonate is precipitated in soil below a pH_c value of 7.44, while above a pH_c value af 7.52 calcium carbonate starts dissolving. Precipitation of calcium carbonate enhances the sodium hazard in soil while its dissolution decreases the latter. Higher salinity favourably influenced the ralease of Ca and Mg. ESP of all the soils correlated significantly with the values predicted by the equation: ESP = [SAR 1 + (8.4−pH_c)]