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.
Arctic seed vault meltdown - SUBHEAD: Arctic Doomsday Seed Vault imperilled by unanticipated global warming. Who knew? By mary Papenfuss on 20 May 2017 for Huffington Post - ( http:/...
19 hours ago