Humic acid composition and soil fertility of soils near an ancient charcoal kiln: are they similar to Terra Preta de Índios soils?

Purpose Charcoal production during the nineteenth century transformed landscapes in the Brazilian Atlantic Forests in Rio de Janeiro city. These paleo-territories were studied to improve our understanding of how this activity altered soil properties. By comparing their humic acids (HA) with those extracted from a Terra Preta de Indios (TPI) site, we showed that the aging of charcoal in soils alone is sufficient to generate recalcitrant organic material with high cation exchange capacity (CEC).