Sustainable tank irrigation: An irrigation water quality perspective

Thiruvallur district, a newly formed district bifurcated from erstwhile Chengalpattu district is located in the north east part of Tamil Nadu, India with agriculture as main occupation. The total cultivated area of the district is 184198 hectares. Nearly 47 % of the total work force is engaged in agriculture supported by tank irrigation. In this study, 10 major irrigation tanks in the district was selected and analyzed for its water quality during the period Oct to Dec 2010 (northeast monsoon). The objective of this paper is to develop a better understanding of the effect of water quality upon soil and crops and to assist in selecting suitable alternatives to cope with the potential water quality related problems that might reduce production under prevailing conditions of use. The parameters studied include salinity hazard, sodium hazard, pH, alkalinity and other specific ions like chloride (Cl), sulphate (SO4 2-) and nitrate-nitrogen (NO3-N). Out of the 10 irrigation tanks investigated, problems related to salinity and sodium hazard was identified in irrigation waters of two tanks. The potential severity of problems that can be expected to develop during long term uses is studied for all the tanks and special management practices required to maintain acceptable crop yields is suggested