Uso do fino de carvão vegetal e da adubação potássica na produção de berinjela (Solanum melongena l.) em latossolo amarelo antrópico da Amazônia Central

Abstract

In the Amazonia, most of the soils of firm earth presents good physical characteristics and low natural chemical fertility. In those areas, it stands out the occurrence of stains of soils with superficial horizon of dark color, denominated Terra Preta (Anthrosol of Amazonia), with high fertility levels being, for that, used for the agricultural exploration in a wide and intense way. In spite of that, it is observed that these soils, they present a reduction of the natural fertility after years of intense agricultural use, that it affects, mainly, availability potassium. In that way it becomes necessary to look for alternatives of fertility management of those soils. In that sense, given the high availability of residues of charcoal in the area, this study was developed with doses of charcoal and of potassium with the objective of evaluating the effects of the addition of the fine charcoal (waste) and potassium about the availability of nutrients in the soil, nutritional state and in the eggplant productivity. The experiment was growth in an Terra Preta (Anthrosol of Amazonia) in the km 30 of Road AM - 070, in the Extension of the Serra Baixa district of Iranduba, AM with geographical coordinates 03° 30' S and 60° 20' W. The experimental design was in the casual blocks, in factorial 5x3, with four repetitions, where the first tested factor was the potassium in form of potassium chloride in five levels of KCl, 0, 125, 250, 375, 500 kg ha-1 and the second tested factor was charcoal in three levels 0, 5, 10 ton ha-1. Before and after the experiment samples of soils of the 0 - 20 cm layers and 20 - 40 cm of depth were collected for fertility analysis. At that time of the flora samples of leaves were collected for obtain of the concentration of nutrients in the leaves. The variety of eggplant was Ciça. Doses of KCl increased the pH and K+, Mg++ and Mn contents of the soil, and they also made positive the leaf content of Ca, Mg and K, however reducing the Zn and Mn. Meanwhile, the charcoal affected negative the contents of Mg++ in the soil and of Ca and Mg in the leaves. There was interaction among the fertilizer and charcoal factors on the variables concentration of the leaf content of Mg, K and P and productivity that, for its time it had answer the KCl of growing quadratic tendency to the dose of 301 kg ha-1 of KCl. The best profits were obtained with 375kg ha-1 of KCl (Benefit/Cost = 5,79) and with the combination of 250 kg of KCl ha-1 added of 10 ton ha-1 of charcoal (Benefit/Cost = 5,69).