The 'Terra Preta' phenomenon:

A model for sustainable agriculture in the humid tropics

authored by

Bruno Glaser, Ludwig Haumaier, Georg Guggenberger, Wolfgang Zech

Abstract

Many soils of the lowland humid tropics are thought to be too infertile to support sustainable agriculture. However, there is strong evidence that permanent or semi-permanent agriculture can itself create sustainably 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 substances 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 investigations showed that 'Terra Preta' soils contained up to 70 times more black carbon than the surrounding soils. Due to its polycyclic aromatic structure, black carbon is chemically and microbially stable and persists in the environment over centuries. Oxidation during this time produces carboxylic groups on the edges of the aromatic backbone, which increases its nutrient-holding capacity. We conclude that black carbon can act as a significant 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 investigate 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 particulate organic matter in undisturbed soils of the Venezuelan rain forest (Tiessen et al. 1994). Inorganic fertilizers are often too expensive for the indigenous population to use and their effect is only short-lived due to the low nutrient-holding capacity of the poor soils.

External Organisation(s)

University of Bayreuth

Type

Article

Journal

NATURWISSENSCHAFTEN

Volume

88

Pages

37-41

No. of pages

5

ISSN

0028-1042

Publication date

24.01.2001

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Ecology, Evolution, Behavior and Systematics

Sustainable Development Goals

SDG 2 - Zero Hunger, SDG 15 - Life on Land

Electronic version(s)

https://doi.org/10.1007/s001140000193 (Access: Closed)