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Cacao tree productivity as a function of soil characteristics: I: chemical characteristics

The yield of 36 cacao trees (Theobroma cacao L.) on a farm in Itagibá, Bahia, Brazil were evaluated during the period of 1989-1995. The averages of the three highest yields (rainier years) and of the three lowest yields (drier years) of each area were considered the main variables. The variables were the chemical characteristics (pH in H2O and in KCl, organic carbon, total N, Al, Ca, Mg, P, K, Na, Cu, Zn, Mn, Fe, H + Al and the remaining P) inrelative to two depths (0-20 and 30-50 cm) of soils with different textures. Data obtained from routine analysis (pH, Ca, Mg, P and K), in 1995, were correlated with the values of these variables obtained in 1988 and 1991, to verify whether the present fertility would be correlated to a past condition. Soil P and K supplied by fertilization, underwent changes through this seven year period, while the pH, Ca and Mg remained more proportional. Copper was the nutrient which most restricted cacao tree; Ca, P and N also limited yield, mainly during the rainy years. K, Mg and pH were high in some areas, showing significant and negative effects on yield. In drier years, the less productive areas presented more fertile soil (probably the younger ones), with less buffering capacity and less organic matter content. Regardless of rain availability, among the areas with loamy soils, the most productive had higher buffering P capacity.

cacao; productivity; alteration in soil fertility; path analysis


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