Terra Preta de Indio

By re:char fellow Lou Gold

tp

“What we do in the next two to three
years will determine our future. This
is the defining moment.”


— Rajendra Pachauri,
director of the UN’s International Panel on Climate Change

The story that defines what we might do has been
emerging from Brazil.

It’s a golden opportunity.

First, the story…

Once upon a time, way back in the sixteenth century, the Spanish Conquistador Francisco de Orellana was the first European explorer to travel up the Amazon River and into the Rio Negro, a huge tributary, upriver from present-day Manaus. The exploration reached perhaps some 1500 miles from the Atlantic Ocean. For Orellana and his unfortunate companions it was a terrible trip plagued with every kind of adversity which, in the end, left him as the sole survivor to return to the Court of the King of Spain to tell the story.

But what a story it was. We might even speculate that Orellana survived the ordeal in order to complete his mission of telling of having found Eldorado — fantastic golden cities in the heart of the forest of the New World. Orellana reported something even more unbelievable than gold — there was an advanced indigenous civilization with many high density human settlements. Huge Indian populations were living along the waterways of Amazônia and, according to Orellana, at one place there was a city of continuous side-by-side houses stretching for twenty miles. His tale was both fantasic and fabulous. I doubt that the Spanish Court could really embrace the thought of a civilization more advanced than their own but they sure could imagine the gold.

Gold lust inspired many later adventures across the New World but none could find the fabled Eldorado. It was nearly a century later that missionaries came to the region explored by Orellana, but they reported finding only small nomadic bands of hunter-gathers roaming the forest. The obvious conclusion was that Orellana had fabricated a great tale to mask his own failed expedition. And, much later, a whole generation of modern scientists confirmed the implausibility of an Eldorado in the forest by noting that the nutrient poor Amazon soils could not have supported a large-scale agriculture which is the prerequisite of civilization.

But this “well etablished view” that the Amazon basin could not have contained large human populations has started to crumble. First with new research in Bolivia and, more recently, in central Amazõnia, scientists are discovering tell-tale signs of ancient large-scale populations. The indians appear to have figured out how to transform the nutrient-poor yellowish soils into deep deposits of an extremely fertile dark earth called terra preta de indio. What are these tell-tale signs? Terra preta soils are loaded with pottery sherds and charcoal. The pieces of ceramic are in the contour of large pots and vessels that could have been used only by stationary populations. And the charcoal — apparently char from cleared forest — has been ground into small pieces indicating that these soils were “made” by the local residents.

The resulting soils are amazingly fertile — sometimes producing nearly 800% more plant growth compared with nearby untreated soil — and clearly capable of supporting a large-scale agriculture. Also anthropologists have found at least one small tribe with an hierarchical cultural structure suggesting a distant past of living among large sedentary populations and not always as nomadic hunter-gathers.

Recent efforts to map the areas of terra preta soils along the Tapajos River have unearthed esquisite 2000 year-old pottery. Carbon dating of soils in some other areas suggest that they may be 2500-4000 years old — and still fully fertile which is extraordinary in the Amazon where heavy rainfall typically leaches the nutrients out of the soils rather quickly. Interestingly, the mapping efforts are revealing a close correspondence with the Eldorado areas talked about by Orellana.

So what happened to these lost civilizations? No one knows for certain. There’s little hard evidence because there is no stone in the area and the wooden structures were quickly reclaimed by the tropical forest. But the best speculation is that the first European expeditions carried in diseases — smallpox, measels, flu, even the common cold — to a population that had so harmoniously co-evolved with its niche that it had no disease … and no need for immunity. After a catastrophic die-off there were only a few survivors who had devolved back into hunter-gathers. The sole legacy of the civilization remained hidden in the soil.

Today, in some areas, terra preta is harvested and sold as potting soils. If a limited amount (about 20 cm deep) is retained and the area then left fallow it will grow back to full depth in about 20 years. Apparently — get this! — terra preta soils develop into organic communities that are capable of growing like a biotic culture as in sourdough bread or yogurt, truly a living earth.

Five years ago, England’s BBC did a special TV documentary called The Secret of Eldorado that concluded with these words: “So there is a true irony to the story of the hunt for El Dorado. There was once a great civilisation in the Amazon, one the Europeans destroyed even as they discovered it, but the Amazonians may have left us a legacy far more precious than the gold the Conquistadors were seeking. That black earth, the terra preta, may mean a better future for us all.”

A golden opportunity.

At the time of the 2002 BBC documentary, a better future was understood as gaining the ability to BOTH save the rainforest and feed more people. But, now, global warming has added an incredibibly important new dimension — the need to remove CO2 from the atmosphere and sequester it somewhere. This is exactly what terra preta does because 1) plants that grow faster, also remove CO2 from the atmosphere faster and 2) if the agricultural waste (unused portions of the plants) are made into charcoal, it can be used to renew the soil and sequester carbon.

The result of such a system would mean better soil, more food, cleaner fuel, less deforestation and, if Kyoto is revised to include payment for carbon negative sequestration in the soil, developing countries like Brazil and poor farmers everywhere will be paid to save the earth, while growing both food and fuel. This is why terra preta is being called the “new black gold”.

Everyone, who thinks of Brazil, knows of its gifts of samba and soccer which are world renown. But Brazil is also the place where the gift of light emerges out of darkness. When gold was discovered in the state of Minas Gerais, it was given the name ouro preto (black gold) because the nuggets had a dark coating. Later, when a statue of the Virgin with dark skin was discovered in a river bed, it was named, Nossa Senhora Conceição de Aparecida (Our Lady of Conception who Appeared) because it appeared to have wish-granting and healing powers. And, for me, this image is one of the great symbols of the fertility and abundance of Mother Earth.

Nossa Senhora Conceição de Aparecida

This Black Madonna became the patroness of Brazil and the center of the largest healing shrine in the world. Perhaps She is also a powerful symbol for the possibility of healing the earth.

Nowadays, we have the rediscovery of an empowering dark earth brew called terra preta, along with speculation of an ancient and highly advanced Indian civilization. Perhaps terra preta will be Brazil’s greatest gift yet to the world. Perhaps we can all spread the story about how there once was a time when large numbers of people lived in a bountiful harmony with the earth in a place called Eldorado and that, with love and care and attention, we can repeat the performance.

Here are links to more information:

Australian Broadcasting Company video (11 min) about the global terra preta movement.

GREAT BBC Documentary “The Secret of El Dorado” (49 min video)

Full transcript of BBC El Dorado documentary.

Easy to read primer on Terra Preta.

Expandable Google map of Terra Preta sites.

Pdfs of the best magazine articles.

Continuous updates of all relevant links.

How biofuels can become carbon-negative and save the planet.

US Senator introduces bio-char legislation.

Research confirms bio-char in soil increases yields.

Biopact on the IPCC bio-fuel recommendations.

UPDATE: This post has been linked in a roundup by Global Voices Online, and translated to Portuguese here.

, , , ,

2 Responses to Terra Preta de Indio

  1. Blayde April 19, 2009 at 9:27 am #

    I would like to know more about the pot shards. This sort of pottery is usually impregnated with carbon and very porous.

    This could have been used to maintain proper moisture. If the soil were subject to too much moisture the shards could have been used like lateral tiles to drain water off between the soil and the substrate, which I am guessing has a high clay content. What do they know about the shards?

  2. Lou Gold April 19, 2009 at 9:58 am #

    Bladye,

    You can find some discussion of the pottery shards here:

    http://terrapreta.bioenergylists.org/search/node/

    My personal (non-scientific) speculation is the soil-amending stock came from the middens where the wastes created a complex mix including lots of broken pottery (quite common with low-fired clay). Subsequently, the shards could perform several functions in the soil, including providing structure to slow erosion and compaction as well as possibly containing inoculations of mychorrizal fungi.

    lou