Saturday, 15 July 2006

Anthrosol Diversity in Brazil: Terras Pretas, Terra Mulatas and Sambaquis.

Carlos E.G.R. Schaefer, Departamento do Solos-Universidade Federal de Viçosa, Campus da Universidade, Viçosa, Brazil, Guilherme R. Correa, Departamento de Solos, UFV, Viçosa, 36571-000, Brazil, and Hedinaldo N. Lima, Universidade Federal do Amazonas, Campu UFAM, Manaus, 36571-000, Brazil.

The anthropogenic soils (Indian Black Earth-IBE) of Brazil comprise a great number of different soils, with varying morphologies, nutrient and physical status. However, they usually possess high P content and natural ferrtility greater than adjacent, non-anthopogenic soils. This paper highlights the chemical differences between Terra Preta, Terra Mulata, Lagoa-Santense Caves and Anthosols developed on shell-midden deposits, called Sambaquis, in Brazil. Terra Preta from the Solimões-Amazon river systems have a consistent high P content than Terras Pretas from the Negro and Trombetas River systems, as a consequence of contrasting richness of their floodplain and rivers. Degraded froms of Terra Preta are somewhat similar to some Terra Mulata sites, being generally less fertile with respect to Ca and P. Higher OM content in all cases are related to burning, either past, during the indian site occupation, or after abandonment and caboclos cultivation, even recent. Shell-midden sambaquis soils have a high fertility, developing mollic epipedons on the top of bioclastic Ca-carbonate deposits. There, P is also high due to mixture of animal and human bones of varying origins. A newly described site of buried Terra Preta soil (Sítio Caetano) in the Amazon floodplain (1.2 metres below the surface) was studied in detail, revealing extremely high P and Ca levels in the black layers, as well as abundant charcoal and pottery fragments, indicating that human pedoturbation was part of the land use culture at the time of indian occupation, and prior to pedoturbation due to later pedogenesis. Detailed studies of these Várzea pre-colonial, buried IBE can help to elucidate aspects of the population distribution, carrying capacity, patterns of occupation and land uses of ancient Amazon civilizations.

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