Sustainable Agriculture for a Sustainable World

Terra Preta Soils

Terra Preta is short for "Terra Preta de Indio," the Portuguese name given to bodies of dark, fertile, man-made soils primarily found in the Brazilian Amazon Basin and believed to have been created by pre-Columbus indigenous populations somewhere between 500 and 5,000 years ago. Analysis shows it contains not only burned biomass such as charred wood fragments but also pottery shards, fish and animal bones, manures, and nutrients such as nitrogen and calcium. Terra Preta was likely created by cutting and smoldering trees and other woody forest biomass during land-clearing, and/or by similar smoldering of community “dumps.” It’s believed that these soils produced crops and food enough to sustain very large populations in the Amazon Basin, an area not previously believed to be so sustaining due to the highly-weathered, low-nutrient content soils native there. Centuries later, areas with Terra Preta soils still tend to retain their rich color, fertility, and productivity, even in the absence of additional inputs. These soils have a very high carbon content due mainly to biochar material, which is also recalcitrant to decomposition. Biochar production and utilization processes today are largely trying to replicate the functions, properties, and impacts of the Terra Preta soils.