Quote:
Originally Posted by sirdoofus
My question is this: is there a significant difference between the 'charcoal' from the burn pile and the tdud burner?
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Initially, yes. Over time, not really. The goal is to make Terra Preta, which will enrich your soil and continue to do so over long periods of time. If you harvest the stuff from the burn pile quickly, before it rains, you will retain a lot of nutrients that leach out easily. You can reclaim them later on, by using the dirt under the pile in your mix as well. You will still need to activate it, but it will have more minerals in it. It will also tend to have a higher pH, so you may have to add an amendment like sulphur (I'm sorry, I just can't spell it with the modern F in there) to bring it down if necessary
The pure charcoal will need to be activated and it will have a more neutral pH. It's all in the details. If you want to make real Terra Preta, use the stuff from your burn pile and maybe break the bigger pieces up. Add sawdust and other composting materials like coffee, grass clippings, meat and bone scraps; anything that will break down, and let it sit for a few seasons, turning occasionally. You can also add some sand. When you harvest this, just like a crop itself, make sure you get all of the dirt from underneath as well and mix it thoroughly.
Terra Preta was essentially what came out of garbage pits. They found it was very fertile, and began a regime of mixing it into their poor soils. While the potsherds may act like stones in your garden, do you really want it there? The broken pottery is in the original formula simply because these were trash heaps. I suppose you could recreate this with gravel or volcanic cinder (what most stores mistakenly call lava rock), but it certainly isn't necessary. Since you're in BC, you probably have access to some good, rainforest floor humus nearby to add in as well.
Probably longer than you wanted, but while it was technically a yes/no question, it needed some further explanation. If you ever have the opportunity to visit a place like Yellowstone that has burned, look at the same spot ten years later, and you'll see the advantages of having all the other things like ashes in the ground as well.