Terra preta is a "hot" topic in the environmental sciences. From an anthropogenic soil type of local relevance, terra preta has been transformed by soil scientists into a techno-scientific object that helps to escape the global ecological crisis. The commodification goes along with a mythification that does not spare the scientific sphere. Terra preta de índio: Commodification and Mythification of the Amazonian Dark Earths erras pretas (Portuguese for black earths) cover only small areas of usually two to 20 hectares in the lowland regions of Amazonia (sometimes much smaller). These soils-also named Amazonian Dark Earths-are mainly found in the vicinity of rivers. They are characterized by a significantly higher nutrient content compared with other Amazonian soil types (especially available phosphorus and nitrogen, but also other minerals like magnesium and calcium) and show a higher pH value, around 6.7, nearly neutral, which is maintained over a long-term period (Zech et al. 1979, Pabst 1993, pp. 18-20). They areas the name indicates-dark, contain large amounts of black carbon originating from incomplete combustion of organic materials ("biochar" in the anglophone literature), increased amounts of organic matter, and usually fragments of pre-Columbian potsherds. According to the current state of knowledge, they cover an area of 0.1 to about 0.3 percent or 6,000 to 18,000 squarekilometers of the wooded Amazonian lowlands (Woods and Denevan 2009, p.1). They were formed between 2500 and 500 years before present, approximately. These soils are very valuable, as they show enduring fertility, and many of them are used for agriculture. The dominating primary forest soils in the Amazon lowlands (especially oxisols) are extremely nutrient-poor and acidic. They are not suited for long-term agriculture unless the nutrients are added via artificial fertilizers. The traditional form of cultivation in the Amazonian tropics is slash-and-burn. Through the burning of the biomass, which yields ashes and coal, Terra preta de índio: Commodification and Mythification of the Amazonian Dark Earths

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