Quote:
Originally Posted by davidgmills
I had wondered whether the Amazonians had gone to the trouble of meticulously grinding up their charcoal as it seemed highly labor intensive. Maybe they did not grind it up after all.
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You are right, David, they didn't. Nor did they bother spading it in. Recent thinking (Lehmann et al's
Amazonian Dark Earths) is that Terra Preta, black earth, accumulated from burned waste from cooking fires and trash heaps around habitation, while Terra Mulata, brown earth, accumulated from in-field burning. TP may even have been made unintentionally, though personally I doubt that would have been true for very long once they saw what it did. TM seems to have been intentional: see
previous post with evidence from Hecht & Posey on sophisticated uses of fire and mulching in present-day Amazonian agriculture, though this may not be precisely the same management regime as in the past. TM carries just as much carbon, but less phosphorus and calcium, which are what give TP extra fertility.
I'm not sure that we can hope to mimic the Amerindians exactly if we want quick results. But nor am I sure that going for quick results will achieve anything worthwhile. Are you regrowing the char you use? Has it simply been taken from a living carbon sink? Has your digging destroyed more soil carbon than you put in? Are you protecting the carbon so it does not decay?
We should all by looking for ways to answer these questions rightly. For the first, very cheap and IMHO worthwhile tree planting to replace char is available at the
Oxfam Unwrapped site (click on Gifts That Grow). Still time to give as a Valentine's Day gift, though she might not think it very romantic
M
