Assessment of Soil Properties and Heavy Metal Contamination Status in Vegetable Farms along River Sauna

Background and Objective: The use of wastewater for irrigation is a common practice among low-income farmers and is raising serious concerns about the status and contamination level of these farms with heavy metals. This research was carried out to identify the type and amount of heavy metals on the bank of River Sauna. Materials and Methods: The content of heavy metals, cadmium, copper, chromium, nickel and lead in five vegetable farms along River Sauna in Kano State was investigated. Data obtained were subjected to statistical analysis using the JMP package ecological risk assessment of each metal was also carried out. Results: Highly significant differences (p<0.001) in the soil properties across the farms were observed. Most of the farms were sandy loam, slightly acidic with low amounts of organic matter and high amounts of phosphorus. Significant differences in the amount of heavy metals across all the farms were observed with the highest amount of chromium (6.21 mg kg‾¹) and copper (3.11 mg kg‾¹) observed in farm 4. No significant difference was observed in the concentration of cadmium (p = 0.10) and nickel (p = 0.7) across all the farms. Generally, the concentrations of the metals were below the limits expected for arable lands. Conclusion: The amount of heavy metals was observed to be far below the permissible limit and pose a low ecological risk. Practices and legislation to prevent heavy metal build-up in the soils are suggested to be adopted.