Water in agricultural activities is important for satisfying increasing food demands of the ever-increasing population through irrigation practices which was considered as the main alternative for a sustainable agricultural production. A good quality of surface water has a positive effect on soil and agriculture. However, before using surface water for agricultural purpose, its quality should be tested and analyzed to improve productivity of agricultural crops and designing strategies targeted at making remedial solutions for the sustainable utilization of water resources for agricultural activities. Thus, this research focused on water quality assessment of two rivers selected in order to determine the concentrations of different ions present in the surface waters before being used for irrigation purpose. Composite water samples of 2 L water were collected within 3 days interval in the month of March, 2015 from the selected ten points along with upper to lower sampling points of each river. Collected water samples were analyzed in Hawassa Regional and Hawassa University Soil Laboratories. The water samples were analyzed for pH, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Calcium (Ca2+), Magnesium (Mg2+), Sodium (Na+), Chloride (Cl-) and Residual Sodium Carbonate (RSC). Also, quality of the water were assessed using Sodium Adsorption Ratio (SAR) and Soluble Sodium Percentage (SSP), calculated from ionic concentrations of Na+, Ca2+, Mg2+ and K+. The result indicated that both rivers water, according to irrigation water quality standards of University of California Committee of Consultants (UCCC), WHO and FAO, are within the permissible limit and safe for irrigation purpose.
Keywords: Irrigation water, water quality, electrical conductivity, sodium adsorption ratio.