The soils from the State of Acre (Brazil) are mostly formed under parent material with influence of Andean orogeny, showing high Ca2+, Mg2+and Al3+ contents concomitantly associated with different combinations of CEC, V and m values. This study aimed to characterize and classify soils of a topossequence under sedimentary material from Solimões Formation, in the county of Feijó, State of Acre, Brazil. Trenches were opened in three points on a topossequence: shoulder (P1), backslope (P2) and footslope (P3). The soils were analyzed by morphology, particle size (sand, silt and clay), exchangeable cations (Ca2+, Mg2+, Na+, K+ and Al3+), potential acidity (H+Al), P assimilable, pH (water and KCl), specific surface, sulfuric attack (Fe, Al, Ti and Si oxides), and mineralogy (sand, silt and clay). The soils were classified according to the Brazilian System of Soil Classification (SiBCS, 2006) and a classification considering the peculiarities of the soils was proposed. The soils have a low degree of pedogenetic development, with minerals of high activity in the clay fraction, and the presence of primary minerals such as feldspar and plagioclase in the sand and silt fractions. The soils were classified according to the current SiBCS as Argissolo Vermelho Álitico plíntico (P1), Argissolo Acinzentado Distrófico plíntico (P2) e Cambissolo Háplico Ta Eutrófico típico (P3).
Western Amazon; pedogenesis; classification; SiBCS
