Assessment of the Impact of Wastewater on Some Dynamic Soil Quality in Kano Metropolis, Nigeria

Abstract

Quantitative data on the physicochemical properties of soil in top soil (0 – 15cm) under wastewater irrigated land in Kano metropolis could provide information about soil quality and management options in order to achieve soil sustainability and enhance productivity. This study aimed at assessing the effect of wastewater use for irrigation on dynamic soil quality parameters whereby some dynamic soil quality parameters were evaluated and then compared among the study locations. The study area was delineated in to: an area where wastewater and ground water are used for irrigation. In each location delineated, one square kilometers (1 KM²) of irrigated land was selected purposively and then divided in to 10 small squares (grid). Soil samples were collected within each of the grids using composite sampling techniques at 0 – 15 cm depth and then subjected to physicochemical analysis of some dynamic soil quality parameter using standard laboratory procedures. The results shows that the mean values of pH (8.3Kcl ± 0.52), EC (155.7 µs/cm ± 31.29), OC (0.45% ±0.13), N (1.1% ± 0.64), P (2.6ppm ± 0.71), K (0.19cmol/kg ± 0.14) and CEC (7.2cmol/kg ± 1.02) in soil irrigated with wastewater were found to be higher than the mean values  of pH (6.2Kcl ± 0.56), EC (46.5 µs/cm ± 19.6), OC (0.27% ±0.08), N (0.24% ± 0.12), P (1.3ppm ± 0.43), K (0.09cmol/kg ± 0.06) and CEC (3 cmol/kg ± 3.1) recorded in soil irrigated with ground water. This indicated that, wastewater has beneficial effects on the selected dynamic soil quality parameters in the area. From the findings it was recommended that, the forms and concentration of the contaminants present in wastewater used for irrigation should be examined and their destructive risk on soil ecosystem should be explored which will help in determine the need (if any) for subsequent remediation practices for the improvement of soil quality in the area.