Effects of copper-based fungicide application on cocoa growing soils and plants in Fenaso of the Amansie Central District, Ashanti Region,Ghana

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2014-11-20
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Abstract
Copper based fungicide remains the most effective way to control the canker that reduces the higher yield of the brown gold, cocoa for the people of Fenaso and the country at large. However excessive application of the fungicide leaves a higher percentage of residual copper in the soil and plants which affects the quality of cocoa produced in the area. 30 selected cocoa farms from Fenaso, in the Amansie Central District of Ashanti Region which had experienced repeated application of copper-based fungicide were sampled to study the total copper in two soil depth of three of spraying age categories together with cocoa parts, namely seeds, leaves and bark. The relationship between copper concentrations and the soil pH and organic matter in the soils were also studied. An unsprayed farm land at the same area was sampled for control. Mean total copper concentration for three spraying age categories-below 10 years, 10-30 years, and above 30 years of the top soil were 22.37 mg/kg, 22.46 mg/kg and 23.97 mg/kg respectively with corresponding mean of sub-soil as 18.08 mg/kg, 17.34 mg/kg and 17.91 mg/kg. Analysis of results indicated that copper concentrations of the soil samples from sprayed cocoa farms at both depths were significantly different from the corresponding copper concentrations from unsprayed farm land (p < 0.05). The analysis also showed a significant difference between top soil and sub soil which indicated that the mean copper concentration of top soil was always greater than corresponding sub soil. No significant difference was obtained in the three spraying age categories on total copper concentration pH values and organic matter content of soil the samples (p > 0.05). The regression analysis of the results indicated positive relationship between total copper concentration and soil pH as well as organic matter. Copper concentration of cocoa beans differed significantly from leaves and bark (p < 0.05). The mean copper concentration of the seeds, leaves and bark were 37.3 mg/kg, 16.10 mg/kg and 16.5 mg/kg respectively. Even though the cocoa growing soil of Fenaso is contaminated with copper based fungicide, the cocoa beans from the area are far below the health risk of consumption. In future, more research should be conducted on different cocoa farms nationwide to complement with the conclusions made in this study.
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A thesis submitted to the Department of Theoretical and Applied Biology, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the degree of Master of Science in Environmental Science,
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