By: Alastair Smith, PhD

Posted: April 15, 2016
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Faculty Post

Terra Preta: Adapting Indigenous Activities to Modern Scientific Practices


One of the key goals of the Political Ecology course is to explore the interrelations of people with their local environment, both historically and through current practices, particularly with regards to the socio-cultural and economic importance of the local natural resources. Living at Villa Carmen Biological Station gives us so many opportunities to learn more about this incredible environment, in particular how people have been managing it for millennia, helping to create the amazing biodiversity we see today. Last week we had the opportunity to explore one example of the social-nature of Villa Carmen by visiting the experimental bio-char facility located at the station, and to learn how local people are using and transforming the knowledge of their ancestors to improve soil fertility, increase biodiversity, and even mitigate the effects of climate change!

Bio-Char Oven: From left to right: Students Jessica Plance and Zachary Froman, ACCA sustainable agriculture employee Don Leonidas Huacac Delgado, Program Intern Brielle Seitelman, and ACCA sustainable agriculture bio-char specialist Sr. Anacleto Lipe Ccaccasto.

Tropical rainforest ecosystems are characterized by nutrient poor and highly weathered soils due to high rainfall and high temperature patterns typical of the region. Terra preta (also known as Amazonian Dark Earth) is a type of soil of anthropogenic origin found throughout Amazonia. Archaeologists and historical ecologists argue that terra preta is formed through the addition of bio-char (incompletely burned biomass) and nutrient rich waste materials such as residue from food production, animal remains, and ash to the soil. Conservative estimates indicate that approximately ten percent of the Amazon region is comprised of terra preta, however locations are still being discovered, usually near larger, white water rivers on terra firme (non-flooded land).

Don Leonidas Huacac Delgado and Sr. Anacleto Lipe Ccaccasto who work with the sustainable agriculture program at ACCA explained the history of bio-char science at Villa Carmen. Using a prototype bio-char oven (one of only four in the world), waste forestry and farming materials, including the native bamboo which infests the trail system at Villa Carmen, are carefully stacked on giant trays, and then set alight. The heavily insulated door to the oven is set in place, and then the atmosphere inside is carefully monitored and controlled. The temperature inside the oven can reach as high as 700 degrees Celsius, and is regulated through the use of an internal sprinkler system to occasionally cool the fire in order to ensure that char is formed and not merely ash. The bio-char burns for approximately six hours before being removed from the oven and left to cool completely. It is then ready to be mixed into the soil, together with the compost produced from the Villa Carmen kitchen.

Sr. Anacleto engaging the internal sprinkler system of the oven.

Don Leonidas and Sr. Anacleto explained several different bio-char experiments that are ongoing at Villa Carmen. Some fields are being tested to determine how much bio-char is needed to make a difference to soil fertility, while others are comparing the effects of different types of bio-char. One particularly interesting experiment is being conducted on differing types of banana plants in order to help establish the best methods of soil recovery after intensive agricultural production, such as at sites like Villa Carmen which were historically used for cultivation and cattle raising for hundreds of years.

Moving forward, the sustainable agriculture team at ACCA are hoping to engage in more studies investigating the important role bio-char can have in carbon sequestration, thereby helping to mitigate the effects of climate change. These scientific experiments are building directly on the Traditional Ecological Knowledge (TEK) of the local Indigenous peoples who have been managing their environments for millennia, helping to create the incredible biodiversity we see today. By visiting the bio-char facility at the end of the semester, we were able to connect many of our theoretical course learnings to an empirical setting, in particular gaining a greater appreciation for TEK, alternate ontologies, and social natures.

One of the banana plant experiments at Villa Carmen.

→ Biodiversity & Development in the Andes-Amazon of Peru

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