Mineralogia, micromorfologia, gênese e classificação de Luvissolos e Planossolos desenvolvidos de rochas metamórficas no semi-árido do Nordeste brasileiro

• Autor(a) principal: Oliveira, Lindomário Barros de
• Data de Publicação: 2007
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1673
• topic: Pedogênese; Solos do semi-árido; Micromorfologia; Luvissolos; Pedogenesis; Semi-arid soils; Micromorphology; Luvisols; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::CIENCIA DO SOLO

The semi-arid areas of Northeast Brazil have approximately 750,000 km2, corresponding to 60% of the total region extension. In this bioclimatic domain, exception for the sedimentary Paleo/Mesozoic areas, the soils have small poor to moderate development degree and are classified as Neosols, Luvisols and Planosols, sometimes surveyed as soil associations, in a complex standard of distribution, making it difficult to separate isolated classes, even in detailed soil surveys. On the other hand, the available knowledge in these soils are relatively small, sometimes restricted to the information produced in the exploratory-reconnaissance soil surveys. In this context, the objective of this work was to study soil genesis and classification of Luvisols and associated soils, developed from metamorphic rocks in the semi-arid environment, based on macro and micromorphological, physical, chemical and mineralogical characterization of representative soil profiles. Four toposeqüences representative of the occurrence of Luvisols were selected in the semi-arid region of Pernambuco and Paraíba States, two of them developed on gneisses (Toposequence I and II), one micaschist (Toposequence III) and another one on phylite (Toposequence VI). The interpretation of the morphological attributes and the results of physical, chemical, mineralogical, and micromorphological analyses indicate that: a) the studied soils were adequately classified in the Brazilian System of Soil Classification up to the third categorical level (Great Groups); b) goethite was the main iron oxide produced from pedogenesis, despite the nature of the parent material; c) there were no micromorphological evidences that the clayilluviation was an effective process in the formation of the clay gradient of the studied Luvisols, and d) the main observed pedofeatures were related to the weathering of primary minerals, mainly of the biotite, the dynamics of formation and dissolution of iron compounds, and the rearrangement of the soil mass caused by changes in moisture, during dry and rainy periods.