Here's an excellent current research piece on biochar production. A little weighty but well worth one's time.
This describes the technique I've found to work best on my site.
Advantages of decay in food system - SOURCE: Andy Kass (firstname.lastname@example.org) SUBHEAD: Vietnam's low-tech food delivery takes advantage of decay and fermentation. By Aaron Vansintjan on 20 Febru...
20 hours ago