In view of the size of the Amazon region and the need to establish connections between landscape and soil characteristics, the aim of this study was to investigate soil-landscape relationships in a toposequence on granite substrate in Santo. Antônio Matupi, Manicoré, AM. The study was carried out along a transect of 3,000 m from the top downwards, where different slope segments were identified. Profile pits were opened in each slope segment, the soils were morphologically characterized and samples collected from the horizons for physical, chemical and mineralogical analysis. For the physical analysis, particle size distribution, water dispersible clay and flocculation degree, soil and particle density, total porosity, and hydraulic conductivity were measured. Chemical analysis involved pH in water and KCl; Ca, Mg, K, exchangeable Na and Al, available P, Al + H and organic C; SiO2, Al2O3 and Fe2O3 (H2SO4 method); free iron oxides extracted with dithionite-citrate-bicarbonate and poor crystalline iron oxides extracted with ammonium acid oxalate). The mineralogy of the sand, silt and clay fractions was determined by X ray diffraction. The changes in the relief favored the occurrence of dystrophic soils on the summit and eutrophic soils at the foot. The variables ??"pH, silt/clay ratio, base saturation and Fed/Fet ratio indicated that the most weathered soils were related with the top positions of the landscape, while soils with lower development degree were related to slope and foothill positions. The clay fraction mineralogy with prevailing kaolinite and gibbsite and small amounts of mica and quartz was relatively uniform in the transect.
soil-landscape; soil genesis; soil taxonomy; Amazon environments
