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Long-term impact of irrigation with sewage water on cadmium concentration in soils and crops

Khurana, M. P. S.; Kansal, B. D.; Setia, R.

Agrochimica 58(1): 19-34

2014


ISSN/ISBN: 0002-1857
Accession: 070718319

Sewage water, a potential source of cadmium (Cd), is generally used for irrigating pen-urban agricultural soils in many developing countries. On the other hand, there are concerns about the food standard and phytotoxicity limit for Cd throughout the world. Hence, a case study was undertaken to study the influence of long-term use of sewage water on Cd concentration in soils and plants. For this purpose, pen-urban agricultural lands in the vicinity of four industrial towns of Punjab (India) were selected where sewage water is used for irrigating crops. The concentration of bioavailable Cd and its fractions was determined in sewage and tube-well water-irrigated soils and the total Cd was also determined in crops (berseem, spinach, fenugreek, mint, raya and wheat) grown on these soils. The sewage irrigation increased electrical conductivity, total and DTPA-extractable Cd, and organic carbon as compared with tube-well water-irrigated soils. On an average, pH of surface (0-15 cm) soils decreased by 0.3 units as a result of sewage irrigation. DTPA-Cd was related to soil properties by stepwise regression models. In the sewage water-treated soils, DTPA-Cd significantly decreased with increase in pH (R-2 = 0.18) but it increased with increase in organic matter content (R-2 = 0.48). The Cd bound fractions were in the order: residue > oxides > carbonate > organic > exchangeable. The application of sewage water significantly increased the concentration of Cd by 10 times in roots and by 6 times in shoots of the six crops compared to concentration of Cd in crops irrigated with tube-well water. Among all the crops, accumulation of Cd was more in raya and spinach with higher content in roots than shoots. Our results suggest that sewage water should be treated to grow crops (including leafy vegetables) for reducing the intake of Cd by humans.

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