Effect of sewage water irrigation on yield, heavy metal accumulation in grain and soil

The shortage of available water for existing living organism received the great attention in present day scenario. One of the suitable alternatives for meeting water demands is the reuse of waste water especially in a field of agriculture to increase the productivity. The Tiruchirappalli district city corporation sewage water is stored near Panchappur and it is stored in open aerated lagoons and eight benchmark sites were selected to monitor the heavy metal accumulation in soil and crops during 2012-13 and 2013-14. The farmer’s were selected in different locations of sewage water ways and they have utilised sewage water as a main source of irrigation for their crops. The paddy variety BPT-5204 was used as test crop. The sewage irrigated field recorded the highest yield of 6230 kg ha-1 than bore well irrigated field during 2013-14. The increased yield in the soil might be ascribed to the enhanced availability of plant nutrients supplied directly through the raw sewage water (RSW) which had higher nutrient potential. The reuse of wastewater in rice cultivation promises a higher yield than the use of groundwater alone. During 2012-13 and 2013-14 the soil samples were collected from sewage water irrigated field and also from bore well water irrigated field to assess the heavy metal contents. The heavy metals like nickel, lead and cadmium were analysed. The concentration of heavy metal found to be in low concentration during the 2014 than in 2013. The Sewage water irrigation had no significant effect on soil heavy metals (Pb and Cd) accumulation in soil regardless of duration of wastewater irrigation. Soils irrigated with treated wastewater for many years were found to have no significant heavy metal concentrations in soil. The soil application of sewage water could offer the double benefit of safe disposal of waste water and also effective recycling of nutrient for agricultural production.