Assessments of heavy metals and soil chemical properties in selected soil orders from southwestern Nigeria

The study was carried out to assess the heavy metals and chemical properties in soil orders from southwestern Nigeria. Soils sampled at 0 – 30 cm depth on Alfisols and Inceptisols from the University of Ibadan, Ibadan, and the Federal University of Agriculture, Abeokuta, Ogun State, were air-dried and sieved before analysis. Heavy metals were extracted using HNO3: Perchloric acid digestion, and the Pearson correlation coefficient analysis was used to determine the relationship between physicochemical properties and the concentration of heavy metals. The results show the soils were sandy, with the pH range of 6.1 – 7.0 (slightly acidic to neutral). The organic carbon of the Alfisols and Inceptisols from Ibadan ranges from 7.36 g/kg – 13.44 g/kg and 15.35 g/kg – 20.48 g/kg, while that of Ogun ranges from 13.12 g/kg – 40.64 g/kg and 3.20 g/kg – 21.12 g/kg. The total N of the Alfisols and Inceptisols from Ibadan ranges from 0.84 g/kg – 1.68 g/kg and 1.40 g/kg – 3.08 g/kg while that of Ogun ranges from 3.36 g/kg – 4.20 g/kg and 8. 69 g/kg – 53.2 g/kg, respectively. Significant differences were observed among the heavy metals analysed across the two locationsThis study shows that the concentration of the heavy metals (Cadmium (Cd), Cobalt (Co), Chromium (Cr), and Nickel (Ni), Lead (Pb) analyzed is below the contamination threshold. However, it is advisable to create awareness of the hazard caused by planting on soils without ascertaining their heavy metal status because of the possibility of metal uptake in the edible parts of crops, which could be detrimental to human health and the ecosystem.