Effect of Sewage Irrigation on Soil Properties, Essential Nutrient and Pollutant Element Status of Soils and Plants in a Vegetable Growing Area around Ahmednagar City in Maharashtra

Effect of continuous irrigation with sewage effluents for more than three decades on soil physical, chemical and biological properties; and major, secondary and micronutrient and pollutant element status of soils and plants in Nalegaon and Burudgaon villages around Ahmednagar city of Maharashtra was ascertained. The physical properties of soils were observed to be improved due to sewage irrigation. An appreciable increase in organic carbon; available N, P, K, micronutrients; and soil microbial count was recorded in the sewage-irrigated soils over that of the well-irrigated soils. Electrical conductivity of sewage irrigated soils was much below the threshold limit of salinity. Long-term application of sewage water resulted in the accumulation of heavy metals in surface soil, the concentration of these elements is approaching the maximum permissible limits suggested. The mean content of total Fe, Mn, Zn, Cu, Cd, Cr and Ni in the soils irrigated with sewage water was 1.05, 1.24, 3.98, 1.51, 2.10, 1.62, 1.24 times as compared to their content in the well-irrigated soils and the concentration of these metals in cabbage grown on sewage-fed soils was higher by 1.11, 7.51, 1.72, 7.66, 4.36, 1.26 and 1.91 times, respectively. The concentration of heavy metals in cabbage plant grown on sewage was higher as compared to their tolerance level indicating their accumulation in plants. The results suggest that sewage irrigation improves soil physical properties and fertility status indicating its potential for use in agriculture. However, accumulation of heavy metals in soil and plant necessitates its safer use after pretreatments to safeguard soil health and reduce the risk of animal and human health hazard.