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Photo by Lou Gold
General News · 10th May 2015
Co-op Gradens Mario
What is BioChar? BioChar is one of the new rages in the field of organic gardening. The practice is to add “microlife” inoculated organic charcoal to garden beds. It’s been trendy for gardeners since anthropologists realized that aboriginal agrarians have been doing it for millennia and with great results.

In a famous Cornell University trial in the Amazon, they got an 880% increase in yield using ancient “50% charcoal” soil when compared to “0% charcoal” soil. While I doubt anyone using a “sea enriched” soil would get anything like those results (still even 10% of that - an 88% increase - would be exciting), charcoal can do a lot of good things for a garden bed.

First of all, it can act as a detoxifier grabbing heavy metals and locking them up – like a water filter. It also “stores” many exotic nutrients (like the kind of stuff you get from kelp) which plants can then choose from, and so minimizes soil leaching by high rainfall. Charcoal adds “tilth” because it is so porous and light. It provides tiny spaces to trap water, air, fungus and bacteria, thereby leaving soil better aerated and moister – a really amazing combination.

Oh Yea, and if you add more than even 5% charcoal by volume at any given time, you could “kill” a garden bed for a year or more. Mixing in some worm casting, rich living compost or inoculated tea and allowing it to “cure” for a couple of months is strongly suggested. It could take a decade or two, or even longer, to get the charcoal content into an optimum range while still producing food from the same soil all the time.

In our instant-gratification/ADHD/gigahertz-to-go world, we don’t usually see value in things that move so slowly. Potentially requiring a multi-generational focus to ensure complete success, BioChar seems like a truly a long term project, a commitment to consistency and patience. It’s a funny thing to be an instant fad.

Professionally made organic charcoal (BioChar) without any “microlife” added yet sells for about twelve dollars a gallon on the internet. While expensive Biochar kilns are now extensively being used, the traditional “third world” method of charcoal production still works fine. Dig a pit – build a fire in it – and then bury that fire under soil. Simply, one wants to create pyrolysis (oxygen starved burning) rather than combustion to make charcoal.

Of course, there are some things to know for efficiency and safety. Improper burning leaves dangerous chemicals in the charcoal (not the best for the garden). Also after burying the fire, the area is potentially explosive for several days. Don’t open it up to find out – a sudden influx of oxygen can ignite a lot of hot fuel immediately. Indeed, you should wait a week or more before digging around to see what you made.

The production of BioChar is a potential middle ground between the opposing viewpoints of 1) burning dry brush on the ground is an important fire safety tactic which everyone living in a forested area should do around their house and 2) we want carbon in the soil and not in the air, so leave brush around as wildlife habitat to rot down slowly - never burn it. I’m guessing that our current BioChar production is sequestering anywhere from a third to a half of the carbon from the brush we are burning. Maybe it is even higher than that, but I have no way to accurately measure it. We do find a lot of “black gold” to harvest once it is safe to look.

Still looking for a “supersoil” additive to grow larger, more nutrient-rich food? Maybe BioChar is your answer, or maybe it’s far too slow and rooted a process for your lifestyle.
If you want a faster return from making charcoal, consider that charcoal slowly is becoming a valued trade item.

If you want to learn more, we are holding a BioChar workshop on Sunday May 17th at 3:00 PM for about two hours. Please register with a Natural Food Co-op’s cashier.

CNFC Members: Free. Non-Members: $15. We’ll have a pit fire and then bury it. While it’s burning down, we’ll open an old pit and look at sifting, sorting, and curing charcoal for harvest. Optional potluck to follow workshop.