I was happy to recieve a gift from black swallow living soils yesterday! They sent me a good 10 lbs of charged biochar. Biochar is charcol made without oxygen and used for the garden and not for burning.
Before you ask the charcol you buy at the grocery store is made for burning not for holding nutrients and microbes. And the briquettes are full of fillers and what not. You can use the hardwood charcol from your store but its pointless. Youd be better off soaking your perlite in a teaXD
You can make it by starting a fire of wood stock in a pit and covering it with soil so smother and smolder it. (Warning: Doing it this way is illegal in some areas due to the large amounts of smoke it makes.)
Another way is to make a ākilnā. Its basicly a metal barrel full of woodstock with some holes in another bigger metal barrel with burning wood put in the area between the smaller and bigger barrel with a chimney. You then light the wood in the bigger barrel on the outside of the smaller barrel on fire on the top and put the lid on the barrel the wood will burn down causing very no oxygen in the smaller barrel and for it to all turn to biochar. Now you take this and you can leave it fairy chunky or you can break it into smaller chunks. But dont powderize it. Now take this and cover it with compost for a week or two. Or put it in a tea of some sort. What were doing here is charging the biochar. You collect nutrients and microbes on and in the charcol doing this then you add it to your soil. If you dont the charcol will charge itself with the nutrients in your soil. You can also use this for aeration instead of perlite, lava rock, pumice, etc. Now you can powderize it if you like but its not needed. I like to have powder, small, medium and big chunks. I do 5 or 6 cups per cuft of good vermicompost. Worms will use this to make tunnels in your soil. These tunnels allow for nutrient delivery, aeration, and to keep your soil loose! Check out http://www.biochar-international.org/biochar for more info on biochar.