Naturwissenschaften (2001) 88:37–41 DOI 10.1007/s001140000193 SHOR T COMMUNICATION Bruno Glaser · Ludwig Haumaier Georg Guggenberger · Wolfgang Zech The ‘Terra Preta’ phenomenon: a model for sustainable agriculture in the humid tropics Received: 7 September 2000 / Accepted in revised form: 14 November 2000 / Published online: 24 January 2001 © Springer-Verlag 2001 Abstract Many soils of the lowland humid tropics are thought to be too infertile to support sustainable agricul- ture. However, there is strong evidence that permanent or semi-permanent agriculture can itself create sustain- ably fertile soils known as ‘Terra Preta’ soils. These soils not only contain higher concentrations of nutrients such as nitrogen, phosphorus, potassium and calcium, but also greater amounts of stable soil organic matter. Frequent findings of charcoal and highly aromatic humic sub- stances suggest that residues of incomplete combustion of organic material (black carbon) are a key factor in the persistence of soil organic matter in these soils. Our in- vestigations showed that ‘Terra Preta’ soils contained up to 70 times more black carbon than the surrounding soils. Due to its polycyclic aromatic structure, black car- bon is chemically and microbially stable and persists in the environment over centuries. Oxidation during this time produces carboxylic groups on the edges of the aro- matic backbone, which increases its nutrient-holding ca- pacity. We conclude that black carbon can act as a signif- icant carbon sink and is a key factor for sustainable and fertile soils, especially in the humid tropics. In the lowland humid tropics, highly weathered soils of low fertility and sustainability predominate (Tiessen et al. 1994). Numerous studies have been conducted to in- vestigate the relationship between soil fertility and land- use practices (e.g. Guggenberger et al. 1994; Tiessen et al. 1994; Kleinman et al. 1996; Westerhof 1998; Thomas and Ayarza 1999). One of the major problems of sustainable agriculture in the humid tropics is the rapid decomposition of organic matter (Zech et al. 1990) due to the high temperatures, large amounts of precipitation, and the lack of stabilizing minerals. Mean residence times of less than 4 years have been calculated for par- ticulate organic matter in undisturbed soils of the Vene- zuelan rain forest (Tiessen et al. 1994). Inorganic fertili- B. Glaser ( ✉ ) · L. Haumaier · G. Guggenberger · W. Zech Institute of Soil Science and Soil Geography, University of Bayreuth, 95440 Bayreuth, Germany e-mail: bruno.glaser@uni-bayreuth.de Tel.: +49-921-552254, Fax: +49-921-552246 zers are often too expensive for the indigenous popula- tion to use and their effect is only short-lived due to the low nutrient-holding capacity of the poor soils. On the other hand, black-earth-like anthropogenic soils with enhanced fertility, known as ‘Terra Preta’ (do Indio), have been described. These usually occur in areas averaging 20 ha (Smith 1980; Zech et al. 1990; McCann et al. 2001), but very large ‘Terra Preta’ sites up 350 ha have also been reported (Smith 1999). It is estimated that the total area covered by ‘Terra Preta’ sites exceeds 50,000 ha in Central Amazonia between the rivers Tapajós and Curuá-Una alone (Smith 1980; Woods and McCann 1999). The ‘Terra Preta’ phenomenon is not on- ly restricted to areas near rivers, but also occurs on the ‘Terra Firme’ at higher elevations (Smith 1999). The similarity of the texture and mineralogy with that of the surrounding soils (Zech et al. 1990) and the occurrence of pre-Columbian ceramics in the upper horizons of ‘Terra Preta’ soils (Sombroek 1966; Smith 1980) suggest man-made soils derived from surrounding poor soils. The enhanced fertility of ‘Terra Preta’ soils is expressed by higher levels of soil organic matter (SOM), nutrient- holding capacity, and nutrients such as nitrogen, phos- phorus, calcium and potassium, higher pH values and higher moisture-holding capacity than in the surrounding soils (Sombroek 1966; Smith 1980; Zech et al. 1990). According to local farmers, productivity on the ‘Terra Preta’ sites is much higher than on the surrounding poor soils. ‘Terra Preta’ soils are equipped with thick carbon- rich topsoils that persist centuries after their abandon- ment by the native Amerindian population. The regular occurrence of charcoal in ‘Terra Preta’ soils (Sombroek 1966; Sombroek et al. 1993) and their highly aromatic humic substances (Zech et al. 1990) in- dicate that residues of incomplete combustion (black car- bon), derived mainly from cooking fires, may contribute to the SOM of ‘Terra Preta’ soils. It has been proposed that polyphenols and condensates (e.g. of lignin-degrada- tion products) contribute the major part of the aromatic compounds in SOM (Stevenson 1994). Recent investiga- tions, however, revealed that at least a part of the aro-