Author(s): SONG, G.; NOVOTNY, E. H.; HAYES, M. H. B.; AZEVEDO, E. R. de; BONAGAMBA, T. J.

Summary: The high and specific SOM contents of the Amazonian Dark Earths (ADE, Terra Preta de Índios), and their high contents of P and Ca provide high natural fertility to the soils. Char or black carbon (B C) plays a major role for the SOM stability in ADE soils (1) and it also provides a significant potential for carbon sequestration and sustainable ecosystems (2). There are several studies of the humic acids (HAs) of ADE soils (e.g., 3 and 4). However, because of the difficulties in isolation, there is less awareness of humin, the most abundant SOM component, and of the interaction mechanisms of recalcitrant BC with SOM (especially humin) and clays. In this study, humic materials were extracted using the IHSS procedure and by exhaustive sequential extraction procedures. Isotopic 13C analyses, and solid-state 13C NMR spectroscopy were used for characterizations.

Publication year: 2008

Types of publication: Paper in annals and proceedings

Unit: Embrapa Soils

Keywords: Amazonian dark earth, NMR, black carbon, char, dimethyl sulfoxide, humin, urea