“Terra preta” (black soils in Portuguese) are fertile anthropogenic soils found in the Amazon basin. They are recognized by abundant presence of charcoal resulting in their dark color, high amounts of phosphorus and calcium, and signs of human influence (e.g. high quantities of pottery sherds). These soils are also known as Amazonian Dark Earth (ADE), "Terra Preta do Indio" (in Portuguese) or "tierras negras" (in Spanish).

 

These soils are remnants of ancient, pre-Columbian societies and were generally created between 3000 and 500 years BP, with the earliest report being 5000 years BP (Meggers & Miller, 2006). These soils were abandoned after the European colonization (Smith, 1980; Woods et al. 2000), probably because Amerindian populations declined by 90 percent within 100 yr after European contact (Hemming 1978). It has been (conservatively) estimated that terra preta currently cover 0.1-0.3% of the Amazon area. The recent estimate by Sombroek et al. (2003) is an order of magnitude higher, reaching 1%. On the other hand, the estimates done by Balée (1989) are much higher: he suggested that Amerindian agriculture, forest and soil management had significantly modified as much as 12% of the Amazon basin.