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In 2011, Earth Dharma Farm received a Conservation Innovation Grant from USDA Natural Resources Conservation Service (NRCS) to study the feasibility of producing bio-char on a small scale.
Bio-char is a component of the "terra preta" or "dark earth" discovered in the soils of the Amazon Jungle, and is thought to be a source of long-term soil nutrients as well as a way to sequester carbon. (Learn more.)
The project uses simulated alder coppice wood and a solar kiln to lower the energy cost of pre-drying the wood. It converts the wood to bio-char with low-cost and low-energy replicable, on-farm pyrolysis units, and incorporates bio-char into the farm composting operation prior to field use.
Pyrolysis, the controlled heating of the biomass at high temperatures in the absence, or near absence, of oxygen, converts the wood (or other biomass) to bio-char, a mostly pure form of carbon.
The bio-char can be used as an agricultural soil amendment to improve crop production and as a method of atmospheric carbon capture and storage. Coppicing the wood (i.e., harvesting young tree growth and leaving the living tree roots to regenerate) adds greater sustainability to the project. Composting the bio-char inoculates it with beneficial microorganisms and soil nutrients and provides a cost-effective method for field application.
The full project report, as well as slides summarizing the project, is available at the link on the left.