Evaluation of Saline and Sodic Water Effect on Soil Moisture Characteristic Curve and Soil physical Quality Index

Despite the growing demand of food and scarcity of fresh water sources, evaluating effect of using saline and sodic water on soil properties is essential.The purpose of this research is evaluation of saline and sodic water effect on soil moisture characteristic curve and soil physical quality index (S). three soil types loamy,clay and sandy, three levels of SAR 5,10 and 20, three levels of EC 4,8, and 12 dS/m and distilled water were used. NaCl, CaCl2 and MgCl2 salts at Ca:Mg=2:1 were used to prepare treatments. Soil samples moisture measured by pressure plate at 3 duplicate and at 8 suctions. Van Genuchten-Mualem parameters determined by RETC and then by using them, S index was calculated, too. Results showed at a fixed SAR and suction, with decreasing salinity, moisture content increased and this increase was more at larger suctions. Effect of salinity and sodicity for loamy and clay soils was more than sandy soil.S index with increasing SAR and decreasing salinity, decreased that seems sodium caused destruction of soil structure. Statistic analysis showed that salinity and sodicity have very significant effect (P<0.01) on Van Ghenuchten parameters and S index. Therefore water quality affects on shape of soil moisture curve and S index.