Effects of fungicide residues on the physico-chemical characteristics of soils of a major cocoa-producing area of Nigeria.

The effects of copper-based fungicide residues on some physico-chemical properties of soils in some cocoa-producing areas of Nigeria were investigated. The results show that the fungicide residues cause significant increases in the soil pH, organic matter and copper concentrations while lowering the concentrations of inorganic nitrogen, available phosphorus, exchangeable potassium and sodium. Slight increases were also observed for the cation exchange capacity (CEC) and exchangeable Ca2+ and Mg2+ but there are no significant changes in the Zn, Fe and Mn concentrations with fungicide treatment. It is concluded that the copper-based fungicide residues predispose the soils to nitrogen, phosphorus and potassium (N, P and K) deficiencies and perhaps copper toxicity if not properly managed.