Avaliação dos atributos físicos do solo em área de floresta Nativa e plantio de bertholletia excelsa bonpl. Na Amazônia central

Abstract

In the Amazon region, the alteration of vegetation cover for the purpose of planting crops has promoted the disruption of the soil's natural balance. Thus, knowing the physical quality of the soil in a given ecosystem becomes important to define the practices to be adopted appropriately, in this context, the evaluation of the impact of different types of use and vegetation cover can help in the direction of techniques related to forest management. In view of the above, the present work aims to determine the physical attributes of the soil under native forest areas and areas of Brazil nut (Bertholletia excelsa Bonpl.) plantations in Central Amazon. The study was carried out in three areas of Fazenda Aruanã, one area of native forest (FN) and two areas under plantation of B. excelsa Bonpl, one area with 3 years of age (CA3) and another with 25 years (CA25). For each area, 64 points were sampled at three different depths, 0.00-0.20, 0.20-0.40 and 0.40-0.60 m, totaling 192 samples per area. Texture, soil density, macro, micro and total porosity, soil resistance to penetration and aggregate stability were analyzed. The analyses were performed in the Chemistry Laboratory of the Center for Higher Studies of Itacoatiara (CESIT/UEA). After the determination of the analyses, the data were tabulated and later the univariate and multivariate statistical analyses were performed. From the results it was possible to conclude that the highest values of macroporosity (MaP), total porosity (Pt), geometric mean diameter (GDM), weighted mean diameter (WD), aggregate stability index (AEI) and class of aggregates larger than 2 mm and the lowest values of soil density (SD) and soil resistance to penetration (SPR) were found in the area FN and CA25, showing that the CA25 area, with the time of establishment of the plantation, is moving towards a new balance, coming close to or superior to native forest in relation to the attributes evaluated. In CA3 higher values of RSP, Ds and lower aggregate stability were found, showing that the physical properties of the soil are altered with the conversion from native to cultivated areas.