Biochar is a great way to add carbon and nutrients into the soil and provide a habitat for microorganisms. In the cold winter months making it can also be a great way to keep warm! Biochar is basically just charcoal soaked in organic fertilizer. Charcoal is pure carbon and it is very porous. One gram of of charcoal can contain more than 1000 square meters of surface area! Nutrients and microorganisms can easily attach to this surface where they are protected from the elements.
You can make biochar out of any thick carbon rich material like wood, corn cobs, or reeds. There are various designs to build a burn chamber out of metal drums, see the links at the bottom of this page for instructions. In the video above we made a simple setup out of things we found at the Earth and it worked really well. You can also just build a camp fire and put it out with water or dirt when the wood turns black, before it turns to ash.
We put smaller sticks from a brush pile in the trash can and filled between the trash can and the barrel with the larger sticks. We put the lid on the trash can and set the larger sticks on fire. We let the outer fire burn all the way down. The combustible gasses were released from the wood in the inner container and burned as they came out of the lid. When we opened the trash can lid, voila! The sticks inside were perfectly blackened.
Charging Biochar
Next I ran the sticks through a wood chipper to grind it up fine and put it in a bucket. It isn’t necessary to break up or grind the biochar but it allows you to spread it more evenly. Then I soaked it in fertilizer. I used organic fish emulsion but compost tea, liquid manure, or urine work great too.
If you can, inoculate it with beneficial microbes. You can buy a mixture like Effective Microorganisms, collect your own with the Korean Natural Farming methods, or just mix the biochar into a pile of compost like I did and it will be naturally inoculated.
You can mix biochar into potting soil, mix it into your compost before spreading it, or just spread it over the surface by itself. Some people even mix a little uncharged char into their livestock feed and let the animals spread it in their manure.
This amount of biochar, about 8 gallons, would normally sell for about $50. It took us about 3 hours and $10 of fish emulsion to make. It’s definitely worth it, give it a try!
Links to More Information
International Biochar Initiative https://biochar-international.org/biochar/
This history of Biochar (Terra Preta) https://youtu.be/vUAEa4ORAkY
Traditional Peruvian pile burn https://youtu.be/KNFDOGWozKU
