Soil Quality of Farmlands Close to Municipal Waste Dumpsites

Abstract

Soil samples collected from some farmlands very close to municipal dumpsites located in Jos, Plateau State were studied to assess the soil quality of the farms with respect to the soil physico-chemical properties and heavy metal concentration. The results show that the soil samples from the farm and control sites are loam while the dumpsites are sandy (contained sand fraction >85.0%). Soil mean pH varied between 5.902±0.02 in Zaria road control soil to 7.16±0.22 in Zaria road farm. While the CEC (cmol kg-1) in the farm soils (14.35±0.66, 12.44±0.20) are higher than that of the control sites (8.35±0.75, 7.41±0.10) and consistent with the dumpsites (23.60±0.02, 21.18±0.01), the percentage organic matter in all the study sites are far above the average level by FAO for agricultural soil. The concentrations of all the metals (Zn, Co, Cr, Pb, As, Cd and Cu) in the dumpsites and farm soil are higher than those of the control, permissible limits of WHO, EU and the DPR target for metals except for Cd. Zn, Co, Pb and Cu were predominant in the sites while As and Cd had low concentrations. With the exception of Zn and Cr in the farm soils, all the heavy metals had anthropogenic inputs of >50%. The index of geoaccumulation results for the metals showed moderate pollution of the farm soils with Cr, Pb, As, Co and Zn; and a strong pollution with respect to Cd. The continuous dumping of waste in these areas may therefore constitute a serious threat to the soil qualities of the nearby farms