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CAMPOS, Milton César Costa et al. Soil-relief relationships in a grassland/forest transition in the region of Humaitá, Amazonas State, Brazil. Acta Amaz. [online]. 2012, vol.42, n.3, pp.387-398. ISSN 0044-5967. http://dx.doi.org/10.1590/S0044-59672012000300011.
The objective of this work was to study soil-relief relations in a grassland-forest transition, in the region of Humaitá, Amazonas State, Brazil. The study area was selected based on the criterion of regional representativity (most common landscape) and in the level of environmental preservation. The sample collection was carried out in a transect from the grassland towards the forest, and the different soil environments were identified and limited according relief position, vegetation patterns and soil characteristics. Soil profiles were morphologically characterized and samples collected from all horizons for physical and chemical analysis for normal profile characterization. including SiO2, Al2O3 and Fe2O3 extracted by H2SO4 attack, free iron oxides by DCB extraction and poor crystalline iron oxides extracted by ammonium oxalate. Mineralogical analysis was also carried out by X-ray diffraction. The results suggest that soil variation in the landscape was directly related with the relief, which determines soil drainage and water table level.
Keywords : soil genesis; soil-landscape relations; soil classification.