Quality of sewage for irrigation in Rawalpindi and surrounding areas [Pakistan]
2001
Khan, M.A. | Ahmad, M. | Naeem, M.A. (University of Arid Agriculture, Rawalpindi (Pakistan). Dept. of Soil Science)
Sewage (municipal and industrial waste water) is being generated daily in large quantity in the main towns. Part of this raw sewage is utilized for irrigating crops grown in and around the towns in our country. Production of the crops especially vegetables and forages is high with the application of sewage as it is rich in organic matter and plant nutrients. However, untreated sewage may also contain excess of soluble salts and heavy metals and its irrigation may result in soil salinity/sodicity and heavy metals toxicity. Therefore, to know irrigation quality of the sewage is very essential for guidance of the concerned farmers. With this objective, sewage samples from 17 sewage irrigated farms located in and around main towns of Rawalpindi and adjoining areas were collected, and analyzed for various parameters of irrigation quality. It was revealed from the results that 41 per cent of the sewage samples were marginally fit for irrigation due to salinity, and 35 per cent were unfit on account of bicarbonate hazard. Moreover, all of these samples were found to have higher levels of heavy metals like Cu, Cd, Ni and Cr, which exceeded their maximum permissible limits as recommended by FAO. Therefore, practice of irrigation with sewage of such quality may cause deterioration of soil by salinity and introducing excessive contents of bicarbonate in soils, and pose health hazards by increasing heavy metals contents in vegetables and crops.
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