Clay mineralogy of some typical soils in the Brazilian Amazon region

• Autor(a) principal: Kitagawa, Yasuo
• Data de Publicação: 2014
• Outros Autores: Moller, Maria Regina Freire
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Pesquisa Agropecuária Brasileira (Online)
• Texto Completo: https://seer.sct.embrapa.br/index.php/pab/article/view/16683
• topic: soil clay mineralogy; Amazon soil; mineralogia de argilas em solos; solos da Amazônia

The outline of the mineral composition in the clay fraction of some typical soils occurring in the Brazilian Amazon region is as follows: In the soils with oxic B horizon, Yellow Latosols, Red-Yellow Latosols and "Latosols Roxo" Soil, kaolinite is predominant, goethite and haematite are found in general, an gibbsite is frequently detected. A small amount or trace of mica minerals occur in several lateritic soils. The presence of the other 2:1-type clay minerals is rare in the lateritic soils. In Red-Yellow Podzolic soils, kaolinite is also predominant, and iron-oxide minerals are always identified. Considerable amount of gibbsite and small amounts of mica minerals and dioctaliedral vermiculite are present in some of these solis. In fite so-called "Terra Roxa Estruturada" soils, kaolin minerals are dominant, but considerable amounts of iron-oxide minerals are found in the clay fraction, so that haematite is especially rich. Metahalloysite is a dominant clay mineral in a "Terra Roxa Estruturada" Soil. A small amount of dioctahedral vermiculite is present in the other soils. The clay mineral composition of the low land soils is a little complicated. Montmorillonite/dioctahedral-vermiculite interstratified mineral and mica minerals are dominant in two Low-Humic Gley soils and a Ground-Water Laterite soils, respectively, although kaolin minerals are predominant in many lowland soils. Small amounts of 2:1-type clay minerals are frequently detected in the other lowland soils. Quartz exists in the clay fraction of all the soil samples.