The objective of this work was to evaluate the variations of the carbon stock and quality and the chemistry alterations of soils of anthropogenic formation with high fertility occurring in scattered patches throughout the Amazon, called "Terra Preta do Índio" (Amazonian Dark Earths - ADE). Twenty-one samples of different depths taken from eleven archeology sites, and four representative soil classes of the region (Oxisol, Inceptsol, Ultisol and Spodsol) were used. The eutrophic character of Amazonian Dark Earths contrast with these representative soils and despite its high fertility, the sites present a great heterogeneity concerning the concentration of total N, organic C, available and organic P, available K and exchangeable Ca and Mg. The ancient antropic action in Amazonian soils resulted in increase of humic acids and humin content and decrease of the fulvic acids, with consequent improvement of the soil organic matter quality. The use of Walkley-Black method presented limitations for the carbon in the anthropogenic soils as compared to the CHNS analyzer.
fulvic acid; humic acid; humin; Amazonian Dark Earths; organic C; total N
