Physicochemical Parameters of Soils in the Poura Gold District: Mouhoun Sub-basin in Burkina Faso, West Africa

The physicochemical parameters of the soils made it possible to assess their fertility and pollution around the gold district of Poura. The 3-fraction granulometry indicates a dominance of sandy soils with a silty-sandy texture. The OM (Organic Matter) content is less than 1%, like most soils in Burkina Faso. The characterization of the fertility of the 26 composite soil samples indicates that 96.15% are of average fertility. The pollution assessment indicates that the measured pH values are between 5.5 and 8, therefore in accordance with the local reference standards in force, while the determination of the ratio of Al on the exchangeable bases and the low phosphorus contents express a very high aluminium toxicity. The electrical conductivities measured vary from 17.5 to 252 μS/cm, with a threshold limit of 2 μS/cm, expressing significant soil salinization. With the Pearson correlation matrix and the PC (Principal Component) analysis, the causes of pollution are attributable to the high contents of Al and exchangeable bases, linked to agricultural and mining activities. The analysis of the geological and pedological context indicates that the origin of Al and the exchangeable bases is natural, therefore pedo-geogenic, attributable to the destabilization of feldspars, ferromagnesian minerals and carbonates under supergene alteration.