BIOCARVÃO E ADUBAÇÃO FOSFATADA SOB A FERTILIDADE DO SOLO E CRESCIMENTO DE MUDAS CLONAIS DE CAFÉ CONILON

Abstract

The biochar associated with phosphate fertilization reduces the adsorption of phosphorus and makes it more available for the crops to absorb, thus increasing the efficiency of use of these fertilizers. This work aimed to determine the influence of biochar and phosphorus on soil fertility, nutrition and vegetative growth of conilon coffee seedlings. The experiment was conducted in a factorial test (2x2x3). Factor A: two clones of conilon coffee (C - 120 and C - 199); factor B: two doses of biochar (0 and 40 t ha-1) and factor C: two sources of phosphorus (single superphosphate-SFS and triple superphosphate-SFT) and a control treatment without biochar and without fertilization with P. completely randomized (DIC) was adopted, with twelve treatments and eight repetitions, with each experimental unit composed of a 5L pot with a seedling. The work was carried out in a greenhouse with daily manual irrigation. They were evaluated monthly: height of seedlings, diameter of the collection and number of leaves. After 6 months, the dry matter production of the aerial part and roots was evaluated. With these data were calculated: leaf gain, absolute gain in height, absolute gain in diameter, growth rate in height, growth rate in diameter and total dry matter. To assess plant nutrition, the levels of macronutrients present in the leaves were determined, to assess soil fertility, the levels of macronutrients o were determined and from these data the sum of exchangeable bases, effective CTC and base saturation were calculated. Simple superphosphate is the most efficient phosphate fertilizer for producing conilon coffee seedlings when the 250 kg ha-1 dose of P2O5 is used. The application of SFS provided the largest increases in plant height and leaf area, the same effect was observed in leaf nutrients. Biochar has specific effects on some soil nutrients, increasing the levels of N, Mg and decreasing the potential acidity. An increase in the nitrogen content of the plant was also observed, but it did not influence the growth of the seedling. There was a synergistic effect of biochar-SFS and biochar-SFT to increase the levels of calcium, magnesium, potassium, nitrogen, and consequently, it has the ability to increase the sum of bases, effective CTC and base saturation. The most suitable genotype to produce seedlings in a greenhouse in Manaus was the BRS Ouro Preto C-120 clone.