Padrões de dispersão de nutrientes em terra preta Amazônica (TPA) podem dar informações sobre atividades antrópicas dos habitantes da Amazônia. Estudos sobre pH, fósforo disponível (P), matéria orgânica (MO) e os cátions trocáveis, Ca 2+ e Mg 2+ , foram realizados em amostras de solos dos horizontes A 1 e A 2 ao longo de uma área com TPA (norte-sul e lesteoeste) em um sítio arqueológico denominado Ilha de Terra, na Unidade de Conservação Floresta Nacional de Caxiuanã, Município de Melgaço, Brasil. Os resultados indicaram que a MO e o Ca são os que apresentam maior dispersão. Correlações mais elevadas foram encontradas entre OM-Ca-Mg às proximidades da área central e levam a inferir que a dispersão geoquímica de MO, Ca, Mg e P em sítios arqueológicos com TPA está relacionada com atividades humanas pregressas.Dispersion of nutrients in Amazonian black earth (ABE) can provide information on human activities of the inhabitants of the Amazon region. Studies on the pH, available phosphorus (P), organic matter (OM) and the exchangeable cations Ca 2 + and Mg 2 + were performed on soil samples from horizons A 1 and A 2 over an area with TPA (north-south and east-west) at a site called Ilha de Terra, located in the Conservation Unit Caxiuanã National Forest, Melgaço County, Brazil. The results indicated that the OM and Ca 2+ are the ones with greater dispersion. Higher correlations were found between OM-Ca-Mg to near the central area. This leads to the inference that the dispersion geochemistry of MO, Ca, Mg and P in archaeological sites with TPA is related to past human activities.Keywords: nutrients, Caxiuanã, soils, Amazonian black earth
IntroductionChemical, mineralogical and micromorphological analysis can be used to interpret human activities from material remains in soils. The abandonment of human activities in settlements does not affect chemical residue remains in soils. The potential validity of the chemical analysis of soil to interpret archaeological finds lies in its ability to predict significant features based on (i) the chemical signatures of total concentrations of multielements such as Ba, Ca, P, Zn, Cu and Pb in soils; 1 (ii) the chemical signatures of floor samples in the Maya region; 2,3 (iii) the available nutrients in soils from the Brazilian Amazon basin, 4-8 known by designations such as black earth, Indian black earth, anthropogenic black earth, archaeological black earth, Amazonian black earth (ABE) 9,10 or Amazonian dark earths. 11,12 The area in which ABE occurs is characterized by well-drained soil, running water and located in a particular geographical setting from which the surrounding areas can be clearly observed. 9 ABE is a soil that can be distinguished from other soils from the Brazilian Amazon because of its high content of Ca, Mg, Zn, Mn, P and C due to the incorporation of bones and organic matter (OM). The high level of organic matter in ABE is attributed to the time of human occupation of the site. [10][11][12][13] According to the soil classification system, ABE sites can be foun...
