Solution ID : Biochar / Terra Preta

The dark amazonian soil ancient secret that could restore the climate and biodiversity.

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Solution ID


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Did you know that burnt wood is an effective fertilizer? However, it also holds the carbon in the ground which is unfavourable for the environment. This Amazonian soil will surprise you!

An ancient ritual that fertilized the earth

First of all, don’t run to the closest forest to put it on fire to fight climate change: this doesn’t work and would actually make things even worse! But have you ever heard of the Amazonian dark soil?

Between 450 BCE and 950CE (before the Spanish conquests), indigenous tribes from the Amazon Basin in Latin America created spots of very rich dark soils by intentionally using charcoal to improve them.

This was first described by the Spanish explorer Francisco de Orellana,  first European to traverse the Amazon River in the 16th century. The phrase “Terra Preta” to describe such a rich soil was just born.

The Europeans, feeling superior to the indigenous tribes, didn’t pay much attention to the potentials of this black gold, and left this knowledge in libraries for hundreds of years before science and biology could explain why this technique is a breakthrough in ecology. 

At the beginning of the 21st century, researchers rediscovered 3 processes responsible for the formation of terra preta soils: 

  • Incorporation of wood charcoal;
  • Incorporation of organic matter and nutrients;
  • Growth of microorganisms and animals in the soil.

It is one of the best solutions we have to reverse climate change, to ensure improved food production without using chemical pesticides and fertilizers, and to regenerate the land!

Carbon brought back to the earth

Ok great, but where could it be done?

Biochar can be produced everywhere and requires a few elements that we can find almost everywhere:

  • Wood or all kind of carbonate material (bamboo, agricultural waste, …) to burn;
  • Manure and urine (from animals or humans);
  • Rich local soil (ideally from a forest) and/or compost;

Making biochar in WholeVillage ecovillage

And concretely what does it do?

Today, researchers confirmed many biochar benefits that include:

  • Reduced leaching of nitrogen into groundwater;
  • Possible reduction of emissions of nitrous oxide;
  • Carbon sequestration;
  • Increased cation-exchange capacity resulting in improved soil fertility;
  • Moderated soil acidity;
  • Increased water retention;
  • Increased number of beneficial soil microbes.

Biochar, bringing soil to life (Carbon Gold)

This sounds too good to be true! Where is the trap?

There is none, we require very few pieces of equipment (1 or 2 stainless barrels or a Kon Tiki depending on the burning method used, a crusher, shovels and bags).

The simplest and cheapest process is the following (the only advice is to do it by 2 people minimum to make it easier):

1) Put your barrel straight and start a fire in the inner bottom.

2) When the top wood of the fire starts to turn black, add more wood (or any dry vegetal combustible) and repeat the process until your barrel is almost full of charcoal. Be attentive not to let full combustion happen or you will have ashes, not charcoal. This process takes generally about 2 to 4 hours.

3) Stop the burning process quickly by filling the barrel with water and a gallon of urine (from animals or humans) to activate the micro-organisms. Let the mixture rest in the barrel for at least 12 hours.

4) Empty the barrel on an outside floor (better wooden planches or cement floor) and crush the biochar in little pieces (about few centimeters max).

5) Add some compost to the mixture, animal (chicken bedding, cows, pigs, …) or human manure, some soil from around the place you would like to use it (ideally a forest nearby for it’s already quite a rich soil, with macro-organisms like worms) and mix it properly with a shovel.

Some people add molasse, sugar, flour and active dry yeast to feed the micro-organisms and speed up the process, but this is not needed. The charcoal should represent about 50% of the total mass of the final mixture.

6) Put your mixture into big bags and let it rest for 2 to 4 months at least to let the micro-organisms and life develop itself.

7) Spread the mixture on a poor soil land where you want to grow something.

You can find many videos with various techniques to make the charcoal, try and see the one you prefer!

    Try this ancient technic and even better, make a test on a similar soil with and without biochar to see the difference! This is free, you utilize unused waste, you don’t need to buy chemical fertilizer that will make your soil poorer in time and pollute the environment and even more, you will make it richer by helping the planet to hold carbon in the soil! A 100% win-win solution!

    Sources & links for more

    1. Lehmann, J.; Kaampf, N.; Woods, W.I.; Sombroek, W.; Kern, D.C.; Cunha, T.J.F. “Historical Ecology and Future Explorations”. p. 484. in Lehmann et al. 2007
    2. Tindall, R., Apffel-Marglin Frédérique, & Shearer, D. (2017). Sacred soil: biochar and the regeneration of the earth. Berkeley, CA: North Atlantic Books.
    3. Glaser, Bruno (27 February 2007). “Prehistorically modified soils of central Amazonia: a model for sustainable agriculture in the twenty-first century”
    5. Glaser, Bruno (27 February 2007). “Prehistorically modified soils of central Amazonia: a model for sustainable agriculture in the twenty-first century”
    7. Instructable about Biochar

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