Bronte, 24.3.23. We organised a field workshop on the production of vegetable charcoal and so-called Terra Preta under the instruction of the engineer Jannis Grafmüller from “Ithaka Institute for Carbon Strategies”, a German pioneer of the revival of this ancient Amazonian technique.
Our aim is to disseminate an alternative method for the disposal of the annual pruning, which, contrary to the usual environmentally harmful field burning here, even has a positive climate balance and furthermore serves as a water buffer in the soil and, with the addition of organics, represents a long-term fertiliser.
The carbonising process we propose to the farmers is rather simple, but it should nevertheless be carried out very carefully in order to obtain a pure end product. The trick is that the wood does not burn, but only its gases that escape under the heat.
The about 47 participants, such as farmers, agricultural workmen and other interested locals, together with our staff and international volunteers, helped to model the previously excavated hollow in the ground and fed the fire with tree cuttings. After about 2 hours we stopped the carbonisation process with water. The result was around 100 kg of biochar. This material now has to be pulverised and mixed with fresh donkey manure before it goes into a 3-month maturing phase. Then the “Terra Preta” (= black earth) is ready to be worked into the soil or applied to it and to unfold its positive agricultural effects and carbon sequestration over the next 1-2,000 years.
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