ABSTRACT Weathering and pedogenesis have been studied for a wide range of rocks and climates around the world. However, the eruption of rhyolitic magmas is a rare geological event, which leads to few studies associated with the rhyolite-soil-landscape relationship. In this context, this study evaluated the influence of rhyolite weathering on the properties of soils along a slope in an Atlantic Forest environment in the state of Pernambuco, northeastern Brazil. Four weathering profiles derived from rhyolites were classified and sampled […]

There is a need to evaluate the importance of soil relief together with soil spectral attributes as the basis on soil mapping. The aim of this study was to test a method for detecting soil boundaries through the interaction of spectral data and relief features. Fourteen toposequences were used, representing an area of 13,000 ha near the municipalities of São Carlos and Araraquara, SP, Brazil. The samples were described by the conventional method of chemical and particle size analysis, such […]

The replenishment of labile phosphorus (P) from less labile soil P fractions was evaluated after 10 successive resin extractions and incubation during four months. Soil samples from the A, B and Bw horizons of Latosols (Oxisols) and A and Bt horizons of Luvisols were collected from the upper, middle, and lower position in the ladscape of three toposequences of each soil class. The evaluation was based on sequential fractionation of soil P with resin, NaHCO3 (organic and inorganic fractions), NaOH (organic […]

The Guaratuba watershed is located at the “Parque Estadual da Serra do Mar” and has its headwaters in the Atlantic plateau. The area has a gneissic bedrock in a parallel hilly relief with high slope gradient, covered by the Atlantic forest consisting mostly of low size trees. The climate is humid tropical with rainfall of 2,000 mm year-1, with no dry season. The predominant soils are Red Yellow Argisol (Typic Kandiudults or Paleudults and Typic or Lithic Hapludults) and Haplic […]

Two toposequences on the coastal plain of Rio Guaratuba (SP) were studied to define the pedological and deposition/storage evolution by means of macromorphological soil analysis. The first sequence shows the change of a Podzol into organic soil on marine sandy sediments, whereas the second one shows the relationship of a Gley Soil on continental sediments with a Podzol soil on marine sediments. Marine sedimentation was found to form sandbanks with internal depression zones, which allowed the development of a Podzol […]