Soil genesis and classification in the environment “mar de morros” in the mid-valley of the river Paraiba do Sul, RJ
Brazilian tropical soils are generally regarded as highly weathered, which is attributed to the climatic conditions (high temperatures and rainfall). However, in the “Mar de Morros” environment the intensity of pedogenic processes can be affected by the erosional removal of material, due to the hilly relief, which rejuvenates the surfaces. The objective of this study was to characterize and classify soil profiles in a toposequence developed from muscovite-biotite gneiss, located in the municipality of Pinheiral (Rio de Janeiro State). The profiles are located in different positions of a toposequence: summit (P1), shoulder (P2), backslope (P3), footslope (P4), and toeslope (P5). The profiles were described, classified and characterized according to the Brazilian System of Soil Classification (SiBCS). The differentiating soil properties were: silt/clay ratio, base saturation (V%), T value, silica/aluminium (ki) ratio, clay fraction mineralogy, and highly crystalline pedogenic iron oxides (Fed). Along the toposequence the soils were classified as Udept in the positions summit and backslope, Udult on the shoulder and Udalf on the footslope, and Aquent in the toeslope plain. The slope position and stratified gneiss parent material were the most influential factors for pedogenesis.