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In yesterday’s post I introduced you to biochar, wonderful stuff that will improve soil while sequestering atmospheric carbon — the only carbon-negative process that has economic benefits that outweigh its cost.

When we think of charcoal, we usually think of wood — as wood charcoal is the kind we are most familiar with. It has been used for thousands of years to provide heat for homes and industrial processes. The problem with using wood to produce biochar is that it is very difficult to reduce it to the powdery form needed for soil enrichment. But charcoal can be produced out of almost any organic matter.

Charcoal is simply the left-over carbon when organic matter is heated to moderately high temperatures in the absence of oxygen. Finding a friable substance to turn into biochar makes the process much easier, as the material will crumble easily. In some places they use rice hulls or coconut fibers to make biochar. Leaves will work well too. Even green leaves could be used, but the energy required to drive off the moisture makes the process inefficient, so it would probably put more carbon in the air from the heating process than could be saved by burying the resultant biochar. If you live in a rural area, dried horse manure makes excellent biochar.

I promised some web resources for you to follow up on this, so I’ll begin with a link to the Twin Oaks site, which has an excellent and efficient charcoal maker, and instructions on how you can make your own. As your dried organic material is heated, it gives off flammable gas, which in this charcoal maker is recycled back under the drum to burn in the fire that is providing the heat — thus reducing the amount of fuel required to produce the charcoal.

For small home experiments, you can just put a covered pot full of organic material in a bonfire. Be sure the top is loose enough that the gasses can escape or you will have an explosion when it expands! The little bit of oxygen in the container will burn off and/or get driven off by the expanding gasses, so your material will turn to charcoal rather than burn. This is an inefficient way to create biochar, so it probably puts as much carbon in the atmosphere during the heating as is saved by the char, but you can produce enough to convince yourself this really works, before investing in a larger operation.

The only dangers associated with biochar are that the fine powder is probably bad for the lungs if inhaled (use a surgical mask when unloading your container), and biochar can be highly flammable. Think old-fashioned ‘black powder’ gunpowder, and one of the ingredients was powdered charcoal. Of course without the potassium nitrate, biochar is not so explosive as gunpowder, but it still can burn fast and furious under the right conditions.

The safest way to sell biochar then is as a component in composted soil. If you have some of that horse manure I mentioned earlier, don’t char it all — save some for compost. Add leaves and similar organic matter, some existing soil for the bacteria and worms and such, and about 25% biochar by volume. The biochar will also help your compost work faster, with less odor. The resulting biochar enriched soil can be sold in those big (reusable) woven-plastic bags used for agricultural crops. It is great in pots for houseplants, or in the garden. Use some in half your own garden, and show people the difference between the biochar side and the regular dirt side, and you will have customers.

Here are some more web resources for information on biochar:

• Cornell University - and Terra Preta - research and resources on biochar and the Amazonian soils that lead to it’s use.
• Biochar.org - further information on current research on biochar.
• Experiment in Iowa — using biochar from dried corn stalks to improve corn production.
• You Tube — one of several YouTube videos showing biochar experiment results. See ‘related videos’ for others.