What is Terra Preta ?
Terra Preta (or 'Terra Preta do Indio' or 'Indian Black Soil') is an anthropogenically (man made) modified, fertile soil, which has developed in small patterns from infertile Latosols (Oxisols) in the Amazon lowlands.
Influence of man is shown by abundance of many artefacts (ceramics) of Pre-Columbian Indians, which have been living in these areas some 2000+ years ago. Indians have 'modified' the soils of their dwelling sites by mulching and compost since thousands of years.
In soil terms, Terra Preta is defined as a subtype of Latosol, which has a high till very high C content (> 13-14 % organic matter) in its A horizon, but without hydromorphic characteristics.
Organic matter can be found in depths of 1 and 2 m (e.g. at 50 cm depth, often > 5 % OM).
The author made the proposal to talk of TP only, if OM content at 50 cm depth is > 2.0 or 2.5 %.
Last updates: 2007/2022