Resposta do cacaueiro em desenvolvimento a calagem

The effect of liming on the correction of soil acidity, the supplying of calcium and magnesuim and the absorption of nutrients by cacao seedlings in pots was evaluated by experimental doses. Two Ultisols (var. dystrophic Vargito and Itabuna Modal) and one Oxisol (var. Colonia) were incubated for 45 days with CaCO3 and MgCO3 in a 3:1 ratio respectively of Ca and Mg. The doses were calculated from tritration curves for pH 5.0, 5.5, 6.0 and 6.5 including a control (without lime). Calcium and magnesium were used both as liming and as a source of nutrients using 70 and 140 mg/pot of a mixture of calcium and magnesium sulphates besides basic fertilization. The experimental design was entirely randomized with four repetitions. Cacao seedlings were grown in plastic pots for 190 days. Liming increased the biomass production of the cacao trees, the maximum production being obtained with a bases saturation of about 50 percent. Liming caused a reduction of Mn and Zn concentration in the leaves and an increase of N, P, K, Ca and Mg absorption in both Ultisols. The mixture of calcium and magnesium suplhates did not change the soil pH but increased the available manganese of the soils of average acidity, besides serving as a source of calcium, magnesium and sulphur. Correlations between manganese in the plant and soil and biomass production established the ranges of 360 - 762 ppm and 7 - 28 ppm, respectively, as appropriate for cacao development.