I've been making my own biochar this year and am just getting into initial testing with growing. Well, not quite yet. I am charging it with compost and then will do some indoor trials on a couple bulbs of new and exciting garlics I've acquired.
I have constructed a two chamber burner, a rocket stove with the drum of would-be-char within, loaded with the right material (relatively packed sticks, up to ~2" diameter) it produces some beautiful stuff. I'm looking to get it down to a nice, fine powder, still thinking on that one. Not a tinkerer, but a machine to aid, like a tumbler or shaker, is what would be best.
Anyway this thread it two years old!! Tell me you've got some explosive news about the char trials, please!