Stefan,
I think that charcoal made in most any fashion from a low temp,
smouldering burn would be beneficial. Keep poking around the resource
page and you will find some other folks rigs for making charcoal.
There is debate about the best size and method for "charging" the
agrichar. Some folks talk about quenching it with water to make
"activated" carbon. Others, myself included, are thinking about
saturating the char with compost tea or other nutrients before
incorporation. There is also talk about the oxygenation that would
occur with the introduction of dry agrichar.
Keep me posted on the chicken front.
When I get moving on the project I'll let you know when we have
projects that can use extra hands.
Best,
Dave
P.S. Yes, we are owed the nice weather!