Assessment of Quality of Wastewater Being Used in Irrigating Soils under Urban Agriculture in Zaria Urban Area

Abstract

The cultivation of food crops in open spaces of cities in the developing world is very common but has not attracted the research attention it deserves. In most areas, the practice relies on the use of wastewater derived from urban sources (houses, industries, markets, public institutions etc) to irrigate soils along the floodplains of streams that drain an urban area. Because such wastewater may be containing some pollutants, concerns are increasingly been raised as to whether urban agriculture is not a threat to public health. There are valid reasons to be so concerned because a wastewater typically contains some pollutants like heavy metals, with tendency to cause several health problems. To ascertain this, a study was conducted to evaluate the quality of wastewater being used in irrigating soils under urban agriculture in Kubanni basin of Zaria area. The results obtained indicate that though there is a presence of As, Fe, Cr, As, Cu, Zn, Mn and Pb in wastewater being used in UPA irrigation practices in the area, their concentrations are generally below the maximum permissible limits set by Nigeria’s Federal Environmental Protection Agency for irrigation. However because of the tendency of the metals to accumulate in soils, it is expected that the metals could possibly have been accumulating in the irrigated soils and the crops being grown on them. Thus further studies are required to establish the extent to which this is so. Nonetheless, it would be worthwhile for the farmers to start some significant purification of wastewater in the area to make it safe for irrigating the soils since there are valid fears to be concerned about possibility of heavy metals build up in the soil.