IRRIGATION QUALITY OF UNDERGROUND WATER IN DISTRICT MULTAN

Water is the basic resource for agricultural production to provide food and feed to humans and livestock and ultimately to livelihood of the people. The productivity of agricultural crop depends on water quality. The irrigation water containing hazardous and higher concentrations of salts affects the crop yield to a far greater extent than any other environmental factors. Therefore, a field survey was conducted in three tahsils of Multan to determine the quality of underground water being pumped. In total, of 2686 water samples were collected. The water samples were analyzed for their salt constituents. Data for quality of irrigation were categorized, from electrical conductivity (EC) point of view : fit [(EC < 1000 µS cm-1), marginally fit (EC = 1000-1250 µS cm-1) and unfit (EC > 1250 µS cm-1)]; from residual sodium carbonate (RSC) point of view, fit (RSC < 1.25 me L-1), marginally fit ( RSC=1.25-2.5 me L-1) and unfit (RSC >2.5 me L-1) and from sodium adsorption ratio (SAR) point of view, fit (SAR< 6 mmol L-1) ½, marginally fit (SAR=6-10 mmol L-1) 1/2 and unfit (SAR >10 mmol L-1)1/2 . The results indicated that water samples in the percentage of 72.0, 62.7 and 54.4 in tehsils of Shuja Abad, Jalalpur Pir Wala and Multan, respectively were found unfit for irrigation purpose. Maximal percentage of 32.4 and minimal 11.6 of water samples were classified as fit samples in tehsil Multan and Shuja Abad, respectively. Thereby, 58.86 % water samples were considered unfit for irrigation purpose. Overall 64.4% and 5.1% water samples had EC and RSC above the permissible limits. The deleterious effects of salts could be mitigated by mixing of brackish water with surface canal water in various proportions and/or intermittent flushing of soil profile with good quality irrigation water. This practice may be carried out periodically to avoid economic yield losses.