Effect of Municipal Sewage on Soil Properties and Chemical Build-up in Vegetable Crops Grown on Haplustepts of Sub-humid Southern Plains of Rajasthan

A mini-lysimeter study was undertaken using two texturally different soils and three sewage dilutions viz. well water and sewage water as such and in their equal proportions for growing cauliflower, carrot and Indian spinach as test crops. Though application of sewage water as such or in its dilutions improved the physico-chemical properties and nutrient status of the soil but did result in a higher per cent build-up of metallic cations in soil and Zn, Pb and Ni in particular, in sandy clay loam soil and Cu and Cd in sandy loam soil. The soil where Indian spinach was raised with sewage water as such or in its dilution contributed towards an increase in organic carbon content while, in soil where cauliflower and carrot were raised, decreased the CaCO3 content. Metallic cation content in the leaves and roots of the crops recorded an increase when crops were irrigated with sewage water as such or in its dilution, though, the metallic cation content in the leaves and roots were quite below the maximum permissible limits. However, a definite metallic cation contamination of crops under study is apparent looking into the per cent build-up of metallic cations in the leaves and roots of the crops under study when irrigated with sewage water as against well water. Results show that there is a need for the establishment of a municipal sewage treatment plant before such waters are diverted for irrigation.