Anyone make their own biochar? I made a few batches of it last summer and tilled it into my garden. Supposed to be good stuff. I have access to a basically unlimited supply of oak scraps so figured id give it a shot. I should have taken more pictures, but maybe I will this spring when I do it again.
Step 1: BURN During this phase all the ‘volatiles’ are leaving the wood. If the fire is enclosed so oxygen cannot get to the wood, the ‘char’ shouldnt burn much at all. Just the gasses being given off will burn when they come in contact with oxygen. Its kind of like wringing out a sponge. The vapor is burning leaving just char in its place, but the char wont burn unless O2 actually gets to it. Wood should turn from tan/brown to black during this phase.
You can tell when its just ‘char’ because the flames will go away, all the wood will be black like charcoal and some pieces will start to turn to ash around the edges, whiteish looking. I usually stir it a few times to break up the larger pieces and this will often get some more flame to show up, but when its mostly gone, all you need to do is seal your container to end combustion. I use a sheet of fiberboard/sheathing with some rocks on top to hold it down and make my burn container air tight. Also before I put the cover on I spray the char down well with a hose to remove a lot of the heat and this also helps to end combustion. Theoretically you could just end it by spraying, but its easier for me to slow it significantly and then seal the container.
Next day I have a big batch of ‘char’ to use how I like.
Bag it up!