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A field study was undertaken to investigate the effect of continuous application of sewage-effluent
irrigation on the DTPA-extractable Cd, Ni, Cr and Pb in soils and crops for five years. For this purpose,
periurban agricultural lands irrigated by different sewage effluent, from a point of entering the effluents
to a distance of nearly 1.5 km and irrigated by ground water from different parts of Aligarh district were
selected where vegetable crops have successfully been grown. The data indicated that the concentration
of these metals in sewage effluent irrigated soils became four to six folds in comparison to ground water
irrigated soil. The data also denote that with increasing soil depth and distance from sewage entry point
the concentration of these metals decreased indicating a low mobility of these metals in soils.Significant
accumulation of heavy metals occurs in 0-15 and 15-30 cm depth. Soil properties viz organic carbon, pH,
EC and CEC exhibited positive relationship with DTPA- extractable metal content, while clay content
showed a negative relationship. The concentrations of Cd, Ni, Cr and Pb in different vegetable crops
grown on sewage effluent irrigated soils were higher (beyond permissible limit) as compared to those
grown on ground water irrigated soils. The maximum accumulations of these metals were in potato
followed by maize except for Pb. These results also denote that potato and maize is good accumulator of
metals hence growing of potato and maize on such soils should be avoided. Higher concentration of
heavy metals Cd, Ni, Cr and Pb due to more accumulation probably may cause phytotoxicity which result
in decrease of crop yield. Based on these results, it can be concluded that proper management of water
irrigation and periodic monitoring of soil and plant quality parameters are required to ensure successful,
safe and long term sewage effluent irrigation.
Keywords: Sewage effluent, Soils,Crops, Heavy metals, Crops.