I have just started making some in my heater I use a Pyrolisis method. I have a large half gallong green bean can I pack full of dry wood kindling blocks in. I put it open side down with old ashes around the base then build the big nightly fire. I get some great lump charcoal. I t breaks up good. I noticed at work when we built a brush pile and some of the dirt from the clearing would smother some of the coals it would later grow a great bush or tree on barron ground. I brought home a 40 yard dumpster full of alder blocks from work and burnt them in my heater and in gave them to friends. I piled up the remaindr in the spring and burnt them. Ther was about 20 yards left and they had burnt down to charcoals. I buried them with the slid steer and a few days later dug them up and sifted out hte ashes. I put them in one row of my Tomato plants and I got noticable results. I sifted and spred the ashes as a lime substitute and the coals in the rows. To pulverize my charcoals to dust I use some bricks in my old cement mixer. It will break them up nearly to dust. I want to make a 200 gallon char plant for my garden operations.
Working along the Tennessee river several years ago we were doing a clearing job. We had a ste Archaeologist that checked for Native American artifacts. We came across 4 foot round circles of black soil about a foot deep. with old river snail shells in them. We learned to look for them by the clusters of plants growing in them and nowhere else.