Impact of copper-based fungicide application on copper contamination of cocoa plants and soils in the Ahafo Ano North District, Ashanti region, Ghana

摘要

The control of the blackpod disease of cocoa is mainly through the application of copper-based fungicides. However, copper-based fungicides use might have negative impact by introducing copper residues in cocoa plants and soils. The study was conducted in selected cocoa farms in the Ahafo-Ano North district of the Ashanti Region to evaluate the effect of copper contained in fungicides on the soil, cocoa beans and leaves. Soil analysis showed that copper contents in the soils of cocoa plantations weresignificantly higher than those of adjacent forest soils. Extractable copper content in the topsoil was similar to that of the subsoil (p = 0.564), although total copper content was significantly higher in the topsoil (p = 0.005). Both extract-able andtotal copper contents of the soil differed significantly among the different aged plantations (p < 0.001). Soils of the various cocoa plantations were contaminated with regard to Contamination Factor and Geoaccumulation index of extractable and total copper in the topsoil and subsoil. Copper residues were detected in both cocoa leaves and beans in amounts higher than soil copper. Copper content of cocoa leaves differed significantly with respect to age of cocoa plantations (p = 0.001) but that was not the case for copper content in cocoa beans (p = 0.227). Extractable and total copper contents in subsoil related significantly with copper content in cocoa leaves (p = 0.004 and 0.04 respectively). Ecological implications of the study have been emphasised.