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 physicochemical properties and heavy metal concentration. The results show that 
the soil samples from the farm and control sites are loamy, while that from the dumpsites 
are sandy (containing sand fraction >85.0%). Soil mean pH varied between 5.902 ± 0.02 
in Zaria road control soil and 7.16 ± 0.22 in Zaria road farm. While the cation exchange 
capacity (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 is 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 the WHO, EU, and the  Department of Petroleum Resources target for 
metals, except  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 pol
lution with respect to Cd. The continuous dumping of waste in these areas may, therefore, 
constitute a serious threat to the soil qualities of nearby farms.