soil characteristics affected by long term application of sewage wastewater

the long term effects of sewage water irrigation on soil properties and heavy metal concentrations at rohtak city, haryana (india) was investigated. at each location, soil samples were collected from the upper layer (0-10cm) for determination of various physico-chemical parameters. heavy metals (pb, cu, mn, zn, cd, ni, and fe) were also determined. the chemical analysis of sewage effluent showed that total salt concentration and heavy metal content was high compared to ground water but within the safe limits. thus, sewage effluent remained within permissible limits for use as irrigation water. soil analysis revealed that organic carbon, phosphorus, calcium and magnesium content were high in sewage irrigated soils compared to tube well irrigated soils. the soil ph decreased by 0.38 units as a result of sewage water irrigation. the continuous application of untreated sewage effluent for last 35 years resulted into significant accumulation of nutrients and heavy metals in soils. organic carbon content showed positive correlation with all heavy metals except zn while ph had negative correlation with all metals except mn. electrical conductivity had a positive correlation with all metals.