Saturday, 15 July 2006

Terra Preta Research: The preSombroek and Sombroek Periods.

William I. Woods, Univ of Kansas, Dept of Geography, Lawrence, KS 66045 and William M. Denevan, Univ of Wisconsin-Madison, Dept of Geography, P.O. Box 853, Gualala, CA 95445.

Amazonian soils are almost universally thought of as extremely forbidding and have often been cited as the fundamental cause for lack of regional cultural attainment. However, it is now clear that complex societies with large, sedentary populations were present for at least a millennium before European contact. Associated with these are tracts of anomalously fertile, dark soils termed terra preta or Amazonian dark earths. Throughout Amazonia terra preta occurs in a variety of landscape contexts, in circumscribed patches of less than a hectare to many square kilometers. These soils are presently an important agricultural resource within Amazonia and provide a model for developing long-term future sustainability of food production in tropical environments. They also have been found to be a significant reservoir for the short- and long-term sequestration of carbon. Beginning in the mid 1870s researchers first published reports of these distinctive anthrosols. Since that time the pace of research and interpretation of these soils have varied widely. Now, instead of merely a curiosity, these soils are viewed by a variety of disciplines as an essential component of any discussion of sustainability in Amazonia – past, present, and future. In 1966 Dutch soil scientist Wim Sombroek based on his earlier dissertation published his classic “Amazon Soils”, which includes descriptions and lab analyses of dark earths on the Belterra Plateau. He made a distinction between black terra preta proper derived from village middens and dark brown terra mulata, a term he introduced to the literature, which be believed "obtained its specific properties from long-lasting cultivation." He was the first to suggest this as far as we know. And he mapped the distribution of dark earths along the bluffs of the lower Rio Tapajós. In 1966 he questioned whether it was "economically justifiable," in his words, to create and cultivate such soil today. However more recently he promoted the idea of developing new dark earth as carbon stores and for intensive cultivation, what he called "Terra Preta Nova." Sombroek, who passed away in 2003, made such fundamental contributions to the study of these distinctive anthrosoils that Wim is now widely referred to as "The Godfather of Terra Preta." This two part paper first discusses the initial or preSombroek period (1874-1965) of Amazonian dark earth publications; a period largely before the modern scientific research begun by Wim, but one that clearly formed the base upon which he built. The Sombroek period (1966-2003) is addressed next. Encouraged and often shaped by Wim, terra preta research during this period has been characterized by increasingly intense attention by a multidisciplinary group of international scholars.

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