Ancient Amazonian soil enrichment technique may provide ‘carbon negative’ fuel

dark earth - a way to cut down our carbon?A lot of money has been pumped into Carbon Sequestration recently, to try and put some of the CO2 we produce back into the earth in the underground aquifers where we got the oil and gas that caused it in the first place. However, another way of storing carbon is in the soil, which benefits agriculture as well. Indigenous tribes in the Amazon basin have been using a technique of introducing charcoal to soil to produce darker ‘terra preta‘ soil for millenia. The low temperature charring of plants and trees introduces more carbon to the soil and encourages worms to break down the charcoal and soil to make a nutrient-rich loam.

A study into the method by MIT professor Amy Smith found that using agricultural char methods could be a great way of producing low-cost fuel for developing nation. You can view a speech on the subject she made at TED 2006 here. By burning waste materials in a gasifier, the methane, hydrogen and other burnable gases it produces can be used as fuels, leaving behind a charred solid that can be mixed into the soil as fertiliser, building back the soil content. Because the organic content has charred, it doesn’t decompose to be released into the atmosphere. WorldChanging has a great analysis that the process could actually provide power whilst potentially reducing the amount of carbon in the atmosphere.

[via WorldChanging, image via Papa Goiaba]

3 thoughts on “Ancient Amazonian soil enrichment technique may provide ‘carbon negative’ fuel”

  1. Cool. But how much energy is needed to run the gasifier?

    One thing I’d like to be able to do is compost my kitchen waste so I can use it as soil for my plants. Something like this could be useful as well. Although, I should probably move out of my apartment first.

  2. I’m guessing it’d be providing energy for much of a village rather than single home use but once it first got started I’d expect you’d be able to divert some of the fuel produced to the gasifier to keep it going sustainably. it looks like most of the energy needed to create the reaction is just from setting light to the materials and the gasifier is a technique to capture the useful released gases.

  3. Terra Preta is the real thing but not primarily for energy. Taking the carbon out of the atmosphere and putting into the soil is the carbon-negative approach that can significantly help reverse our present dangerous climate cycle. But what will induce farmers to use agrichar as a soil amendment instead of selling or using it for fuel. How can we deal with the loss of short-term opportunities?

    The emerging “Carbon Exchange” can create the difference that makes the difference. Those who have no immediate choice about polluting — airline companies for example — can fund those who are able to do the right thing. The right thing is to reward everyone (rich and poor) for repairing soil so that it can it can grow plants faster — pulling CO2 out of the atmosphere and providing more food — which will sustainably provide an abundance for all.

    Charcoal (carbon) put into the soil increases its fertility, stores more nutrients (think less fertilizer), holds more water and filters what is released, pulls more CO2 out of the atmosphere and provides greater production of both fuel and
    food — and the char can be made out of agricultural waste. How’s that for a win/win/win/etc?

    This is the way we can leave the blame-game and help each other. We can jump-start a new no-fault relationship between ecology and economy — a healing one — by focusing attention on the soil.

    It’s all based on recent discoveries of an ancient Amazon Indian technique called terra preta de indio that was able to create a living soil — up to 800% more productive than nearby nutrient-poor tropical soil. It was so successful that it is thought that prior to the Conquest there may have been millions of people living in great cities in the central Amazon without continuously deforesting the forests around them. There actually might have been an El Dorado of people living in harmony with nature. But its history is lost to us. It was devastated when the European explorers carried in diseases for which there was no immunity. The only hints that we have are buried in the soils.

    A 2002 BBC documentary put the first media spotlight on terra preta and 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.”

    Here are some links about what we should be thinking about “on the way to Bali”.

    The ABC 11 minute video about “Agrichar”.

    A lay person’s introduction to terra preta.

    The BBC documentary, “The Secret of El Dorado”tells the story of rediscovering terra preta soils.

    Lou Gold
    An American in Brazil

Comments are closed.