A bio-physical and socio-economic impact analysis of using industrial treated wastewater in agriculture in Tamil Nadu, India

Wastewater has high potential for reuse in agriculture; to reduce the water scarcity problems, for increasing food and environmental security, avoiding direct pollution of rivers, canals, surface water, conserving water and nutrients, etc. The study revealed that the water availability increased significantly during both the rainy season and summer in the open wells as well as the new bore wells sunk in the study area. The area cultivated increased by 24.65 per cent along with change in cropping pattern - changing over from coarse cereals namely; sorghum and pearl millet to commercial crops such as; coconut and fodder grass as inter-crops, beside fodder sorghum in the study area in the current period as a result of use of treated wastewater for irrigation. The livestock activity also moved towards more cattle in place of small animals such as; sheep and goats. The land value per hectare remained higher at Rs. 19.76 lakhs in treated wastewater irrigated farms compared to that of the control farms at Rs. 6.42 lakhs. The employment generation through crop activities in the treated wastewater irrigated farms were higher by 129.79 per cent compared to control farms. The treated wastewater irrigated farms could save farm yard manure and N and P nutrients by 5.02 tons, 270.22 kg. and 31.04 kg., respectively. The net income per hectare increased by 9.32 per cent and 1.42 per cent, respectively, compared to the pre-industry period and the net income in control farms. Even while the pH, EC and salt load remained at permissible levels in soil, the salt loads were found moving towards upper permissible limit or exceeding limits in the case of ground water. The positive externalities while require government to bring in policy, making paper mills to treat effluent and provide for irrigation; the negative externalities when read with WHO stipulations and also on the basis of past studies to go for suitable crops which are seasonal or annual with safe transfer factors regarding heavy metals from soil/ground water to plant parts or fiber crops which are not directly consumed by humans.