Read the full post at Resilience.
Charcoal retains the carbon cell structure of plants from which it is made and, when buried, the carbon can stay in the ground for hundreds or thousands of years. Most fertile soil contains charcoal from ancient or recent forest fires and, until the introduction of synthetic fertilisers, charcoal was widely used by cultivators for enhancing the soil. The most remarkable example of soil modified by charcoal is the deep ‘terra preta’ from a previous civilisation in the Amazon that transformed infertile earth into rich loam.‘Biochar’ is a new term applied to charcoal that is specifically produced for agricultural purposes. It differs from the familiar charcoal used for barbecues or cooking, which is made from wood in relatively large chunks and retains volatiles that increase flammability. Biochar, on the other hand, can be produced from any biological material and the producer should ensure that it is free of volatiles: wood vinegar, for example, is a valuable by-product as a pesticide and if retained in the biochar would hardly help microbial life! Volatiles and ash could also block the entrance to cavities and make them unavailable to moisture, microbes, fungi and mycorrhizae.