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A Bit About Biochar

Over the past eight years interest in biochar has been growing, but it is still a relative unknown outside of certain academic and agricultural circles. The most basic confusion surrounds what exactly qualifies as biochar. Some people have technical definitions about production temperature, quality, and porosity, but at the end of the day it is nothing more than charcoal. What sets it apart from the stuff you put in your grill is the end purpose. Instead of being burnt biochar is put to a use that doesn’t destroy it. This could be as a component of a construction material or as a water filter, but its most prevalent use is as an agricultural amendment. Once in the soil it helps regulate nutrient uptake, meaning it prevents nitrogen from off gassing and potassium leaching, yet makes them available when plants need them.

This is all great, but just as important is biochar’s potential as a carbon sink. While there’s a lot of hype around the idea of using managed grazing to sequester carbon in the soils, the science around how to do this reliably is still unclear. I believe there’s great potential for it to work in some places, particularly on degraded land, but even in the best scenario good farming practices can only keep carbon around for as long as they are maintained. Carbon in biochar, on the other hand, is far more stable, meaning it can persist for hundreds or thousands of years. (Check out this link for a more complete discussion of the topic, including a nifty diagram.)

If biochar is so incredible, why isn’t it ubiquitous? The answer to this is its price. While it can be a useful addition to the soil, there are far more cost effective ways to increase yields. Further, there aren’t that many places producing it, so it often must be trucked in from hundreds of miles away. If the biochar industry continues to mature there will presumably be more local plants and costs should come down. Alternatively, there are awesome (but pricey) systems for smaller scale production. But to my mind the very best solution would be a low tech, cheap way for farmers, foresters, and other land managers to make their own biochar.

This was my first attempt at that. It was a modified TLUD, and it didn’t really work. It burned well enough, and perhaps with some more modifications it could be effective. But every alteration increases the complexity, and I’m after a super simple, easily replicable method. Luckily, this experiment only cost an old oil tank and some scraps of stovepipe.

Since then Ed and I have tried a different design, with much more promising results. But that deserves its own post.

Photo Credit - Garth Brown

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