Caracterização e classificação de solos da Ilha de Fernando de Noronha (PE)

Abstract

In the main island of Fernando de Noronha Archipelago, the dry tropical climate with oceanic influence and the recent parent material of volcanic origin, are responsible for the small weathering of soils with high scientific importance for the development of the Brazilian System of Soil Classification (SiBCS). Seven representative soil profiles, involving two Neosols (Entisols), two Vertisols, and three Cambisols were morphologically, physically, chemically and mineralogically characterized and classificed aiming to contribute to the improvement of the SiBCS. The Lithic Neosol show lithic contact (R) formed by coarse fragments of basaltic rocks (ankaratrites) and is related with strongly rolling topography. The Regolithic Neosol is related with marine sedimentary deposits of the coastal areas. Vertisols were developed on the island central plateau, related with slightly depressed areas and have poor drainage and high levels of sum of bases and base saturation, with increasing values of exchangeable sodium in subsurface horizons. The Haplic Cambisols are the most developed soils of the archipelago, related with several topographic levels and variable slopes in great part of the island central high plain. The studied Vertisols and Cambisols were easily classified in the Brazilian System while Neosols were not due to the presence of specific properties that were not common in the continent, and by that reazon not predictable in the System structure. This work suggested the inclusion of a new great group Fragmentary Lithic Neosol, to include soils with Lithiccontact formed by rock fragments instead of a continuos rock layer, and the subgroup Bioclastic-carbonatic Psamitic Regolithic Neosol in order to include sandy soils developed from marine sandstones and eolic sediments formed by carcareousmaterials from reefs, algae and sea animals.