TERRA PRETA SITES
History
For a long time, the origins of the Amazonian dark earths were not immediately clear and several theories were considered. One idea was that they resulted from ashfall from volcanoes in the Andes, since they occur more frequently on the brows of higher terraces. Another theory considered its formation as a result of sedimentation in Tertiary lakes or in recent ponds.
However, because of their elevated charcoal content and the common presence of pottery remains,
it is now widely accepted that these soils are a product of indigenous soil management involving a labor intensive technique termed slash-and-char. The technique is differentiated from slash and burn by a lower temperature burn (thus producing more charcoal than ashes) and in being a tool for soil improvement.
This type of soil appeared between 450 BC and AD 950 at sites throughout the Amazon Basin.
The Spanish explorer Francisco de Orellana, the 16th C explorer who was the first European to transverse the Amazon River, reported densely populated regions running hundreds of kilometers along the river, suggesting population levels exceeding even those of today. These populations left no lasting monuments because they used local wood as their construction material, which unfortunately rotted in the humid climate (stone was unavailable).
While it is possible Orellana may have exaggerated the level of development among the Amazonians, their semi-nomadic descendants have the odd distinction among tribal indigenous societies of a hereditary, yet landless, aristocracy, a historical anomaly for a society without a sedentary, agrarian culture.
This suggests they once were more settled and agrarian but after the demographic collapse of the
16th and 17th century, due to European-introduced diseases, they reverted to less complex modes
of existence but maintained certain traditions.
Moreover, many indigenous people were forced to adapt to a more mobile lifestyle in order to protect themselves against colonialism. This might have made the benefits of terra preta, such as its self-renewing capacity, less attractive — farmers would not have been able to enjoy the use of renewed
soil because they would have been forced to move for safety.
Slash-and-burn might have been an adaptation to these conditions.
For 350 years after the European arrival by Vicente Yáńez Pinzón, the Portuguese portion of the
basin remained an untended former food gathering and planned agricultural landscape occupied
by the Indigenous peoples who survived the arrival of European diseases.
There is ample evidence for complex large-scale, pre-Columbian social formations, including chiefdoms, in many areas of Amazonia (particularly the inter-fluvial regions) and even large towns and cities.
For instance the pre-Columbian culture on the island of Marajo may have developed Social stratification and supported a population of 100,000 people.
The Native Americans of the Amazon rain forest may have used Terra preta to make the land suitable for the large scale agriculture needed to support large populations and complex social formations such as chiefdoms.
