Open Pit Biochar
1. dig a pit
2. start a fire at the bottom of the pit
3. as wood turns to char, cover with more dry wood
4. when the pit is full of char, hose it down (extinguish).
"First, a fire is started in the bottom of a pit, then dry wood is then added as fast
as the fire will allow - you must always push the fire near to the point of smothering it,
yet without actually smothering it.
It is important to always keep a clean burning fire - no smoke. If it becomes a bit smoky,
back off, let the fire catch up. If it is raging, add more wood to choke it out a bit.
In this way you are constantly covering the char that has been made with fresh layers of wood,
which become char, which are soon covered with fresh layers of wood, which become char, and so on.
When you near the top of the pit or the end of your wood supply, you finish with small
diameter wood. This chars quickly. Let the flames die down a bit, then voila - a large bed
of red hot glowing coals.
By this point, if you have done it right, the entire pit has turned to char. You can either
hose it down immediately, or cover it with soil to snuff it out, then uncover it a few days
later and hose it down. Look to the pictures below for a visual reference."