Soil transformations at the edge of the Pedregulho plateau, São Paulo, Brazil

One of the most important issues in soil-landscape studies is the understanding of how pedological transformations in the slopes occur from the modification of the base level. Local and regional geomorphological processes, such as scarp retraction, drainage captures, modification of fluvial activity in water courses, etc., can lead to important fronts of pedological transformation. In this context, the pedological covers on the edges of plateaus are inserted, with emphasis on the cuestas. This study aimed to investigate the organization of soil cover on the edge of a basaltic-sandstone plateau, in the extreme northeast of the São Paulo state, between 1050 and 850m altitude, in the municipality of Pedregulho. Morphological descriptions and physical, chemical and mineralogical analyzes were performed on the five soil profiles, arranged in toposequence, from the top of the slope to the bottom of the valley. Two pedological compartments were identified. The most common is the latosollic compartment, which occurs from the top to the mid-slope, with the transition from the typical Dystrophic RED LATOSOL to the cambisolic Eutrophic RED LATOSOL. The other compartment is the neo-cambisollic, which occurs towards the base of the slope, with typical Eutrophic Cambisol and a small portion of typical Dystrophic Tb FLUVIC NEOSOL. This transition reveals that scarp retraction has accelerated erosive processes on the immediately affected slopes, and that morphogenetic processes has more intensy with soil genesis in the studied plateau. Thus, the pedological transformation from latosols to cambisols has been caused by erosion in the study area.