Composition of soil and coffee leaves on plantations under varying copper fungicide spraying regimes

A field survey of commercial coffee farms under varied régimes of copper fungicide sprays for over five years was undertaken in Kenya to evaluate the level of available Cu in the soil and its uptake and subsequent accumulation in the leaves of Arabica coffee plants. With the frequent use of copper fungicide sprays, available Cu increased, as did the Cu content of the leaves, in contrast to plantations that had received little or no copper in sprays. No symptoms of copper toxicity were seen in any estate. The general growth of the trees appeared normal, with the foliage of those sprayed with Cu looking greener. The available P content of the soil was lower while extractable Ca, Mg and Cu were higher in the sprayed than in the unsprayed plantations. K, Ca and Cu contents of the leaves were higher in the sprayed than the unsprayed plants. It is probable that the normal growth of the trees and the absence of copper toxicity, despite the increased accumulation of Cu in the soil and leaves, may be due to the large amount of fertilizers regularly applied in the plantations