Terra Preta

Terra Preta (literally “black earth”) is the name for the highly fertile and carbon-rich soil which has been formed by pre-Columbian native populations by incorporating large amounts of charred residues (charcoal) into the soil together with nutrient-rich material (e.g. human and animal manure (rich in P and N), waste including mammal and fish bones (rich in P and Ca), ash residues of incomplete combustions (rich in Ca, Mg, K, P and charcoal), kitchen and garden waste etc.). The charcoal black carbon, due to its polycyclic aromatic structure, is chemically and microbiologically stable and persists in the environment over centuries. Over the time, the persistent black carbon molecules get partly oxidized produces carboxylic groups on the edges of the black carbon backbones which act as a trap for nutrients in the soil preventing them from being washed out. Terra preta has a large potential for preserving fertile soils and for carbon sequestration from the atmosphere as it acts as a long-term carbon sink.