Terra Preta - The parent thread which started it all

[Philip Small]

Originally Posted by davidgmills

Making your own charcoal and terra preta.
... I suggest everyone do it at least once or twice as it is very safe.

I made charcoal using a retort (fire on the outside, wood on the inside) and was impressed by the voluminous smoke it produced. Trying to figure out what my options were with using the smoke led me to other pyrolysis approaches. I have some photos up on Flickr on my backyard run at inverted downdraft gasification for making charcoal.

[davidgmills]

created by the pyrolysis process is the real challenge.

Unfortunately, since I am a lawyer not a scientist, I can't help much with the design. But I had envisioned a ceramic based stove, potentially made out of pottery for third world applications. Even better would be a stove made out of something like soapstone for first world applications.

Modern wood stoves burn exceptionally clean, combusting the gas with catalytic converters or secondary chambers that get intensely hot.

I have kind of envisioned a three chambered stove/barbecue/smoker. The first chamber would have a small amount of sacrificial starter woodstock. The second chamber would contain woodstock for charcoal and the third chamber would be an oven for cooking/barbecuing/smoking. Obviously, the gases produced in the second chamber need to be redirected into the first chamber where they ignite and keep the oven going. Maybe catalytics are necessary here -- maybe not.

But that is what I have envisioned.

If they can make woodburning stoves that recombust all the gases, why not take this technology and use it for making charcoal in our homes?

After all, heating and cooling our homes takes up about 60% of our energy requirements, depending upon location.

[malcolmf]

Originally Posted by Philip Small

Fellow blogger, Back40, and I have been tossing out the potential glomalin link to TP function for awhile.

Where's the blog Philip?
M

[davidgmills]

Originally Posted by Philip Small

I made charcoal using a retort (fire on the outside, wood on the inside) and was impressed by the voluminous smoke it produced. Trying to figure out what my options were with using the smoke led me to other pyrolysis approaches. I have some photos up on Flickr on my backyard run at inverted downdraft gasification for making charcoal.

I thought the retort method used lots of feedstock. That is why I went with a small raging fire in the popcorn can. Much less wasteful of feedstock as even much of the feedstock becomes charcoal once it's flames are extinguished.

[Philip Small]

Originally Posted by davidgmills

I thought the retort method used lots of feedstock.

I place the retort directly on my BBQ briquets after the steaks finish cooking. I could probably get by with a tad fewer briquets if it was just the steak. A downside is that it only works well when there isn't a cold wind blowing. Hot afternoons best. I expect your in-vessel combustion method isn't quite so limited.

[Philip Small]

Originally Posted by malcolmf

Where's the blog Philip?
M

Back40's blog.

My blog.

[Philip Small]

Originally Posted by davidgmills

created by the pyrolysis process is the real challenge.

I would love to be BBQing on an inverted downdraft gasifier. A BBQ retrofitted to make charcoal instead of burning it would be a kick. I'm looking fo a Weber Smoky Joe 14.5 inch....

[malcolmf]

Good post Philip, well worth building on.

Originally Posted by Philip Small

I even emailed Dr. Lehman enthusiastically about glomalin a few weeks ago, thinking to pull my thoughts together on it for a blog post. He was not unaware of the rationale. His entirely neutral response reined me in a bit.

I expect he is on the case but unwilling to say anything until he is safely published. Glomalin drives a coach and horses through much previous TP research, because its effects are so directly relevant that if not factored in, other results are, well, flaky. Give the man time.

it's got to be more complicated than just AMF kicking up their glomalin production

Certain to be true but is it important? Review what we know:

1. Charcoal massively increases AMF growth, and is used extensively for this purpose in Japan. E.g. Saito & Marumoto (2002) 'Inoculation with arbuscular mycorrhizal fungi: the status quo in Japan and the future prospects', Plant and Soil 244(1-2), pp. 273-279.
2. AMF inherently produce copious amounts of glomalin (Driver et al (2005) 'Characterization of glomalin as a hyphal wall component of arbuscular mycorrhizal fungi', Soil Biology & Biochemistry 37(1), pp. 101-106). This glomalin is recalcitrant and persists long after the hyphae have died.
3. AMF are ubiquitous and are productive in tropical forest soil (Lovelock et al (2004) 'Soil stocks of glomalin produced by arbuscular mycorrhizal fungi across a tropical rain forest landscape', Journal of Ecology 92, pp. 278-287).
4. Fire does not reduce AMF the way it does other fungi, leaving them as the dominant group for up to 15 years after a burn (Treseder et al (2004) 'Relationships among fires, fungi, and soil dynamics in Alaskan Boreal Forests', Ecological Applications 14(6), pp. 1826-1838). Terra preta soils were prabably continually burned during formation (Hecht in Amazonian Dark Earths).
5. Glomalin forms water-stable soil aggregates (Rillig et al (2002) 'The role of arbuscular mycorrhizal fungi and glomalin in soil aggregation: comparing effects of five plant species', Plant and Soil 238(2), pp. 325-333).
6. Water-stable aggregates of a similar size to those characteristic of glomalin bind and protect soil components (Teixera & Martins in Amazonian Dark Earths). This accounts for many of the properties of Dark Earth soils: stability; water retention; carbon retention; nutrient retention and reduced leaching; reduced CH4 and N2O emissions.

Perhaps you have heard of Occam’s Razor, or of Einstein’s “smallest possible number of hypotheses”? The important properties of terra preta do not need bacteria to explain them. Bacteria work with AMF (Rillig et al (2006) 'Phylogeny of arbuscular mycorrhizal fungi predicts community composition of symbiosis-associated bacteria', Fems Microbiology Ecology 57(3), pp. 389-395), so as you say the reality will be found to be nonlinear, multi-staged, complex and inter-connected, but they aren’t needed as independent agents.

there are pitfalls to fungi as an explanation for TP's self-replication once it has reached its full expression. By then the pH has come up, not so great for the fungi. By then the phosphorus levels have come up, not so great for mycorhhyzal mutualism.

Self-replication of terra preta is reported by Amerindians but is there any scientific evidence for it? It seems to be one of several questionable beliefs (German in Amazonian Dark Earths), in this case perhaps based on Dark Earth’s rapid recuperation under fallowing. Another such belief is that TP does not lose fertility or break down. It most definitely does if not maintained properly (German again).

pH up? The mean pH of terra preta is 5.7, and of terra mulata 5.3 (Kämpf et al in Amazonian Dark Earths), higher than the awful common soil but nowhere near suppressing fungi.

Phosphorus up? The high P (and Ca) levels in terra preta are believed to be original, from the debris of habitation, not accumulated. They are reported to be the main features distinguishing terra preta from terra mulata, apart from the colour, which is probably due to bacterial decomposition of the debris but has no known beneficial effects. Terra mulata has low P and shows that P does not “come up” in Dark Earths. A useful hypothesis: more glomalin will be found in TM than in TP.

I had hoped that there was no link between TP and glomalin, because then we’d have two weapons against carbon dioxide instead of one. But the scientific evidence is too compelling for me right now. Nevertheless, I cling to the hope of a pleasant surprise when independent glomalin assays of Dark Earths are published.

M

[Philip Small]

Originally Posted by malcolmf

Review what we know:

Much appreciated, and certainly helps me as I wrestle with these concepts.

[Michaelangelica]

Originally Posted by malcolmf

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. M

Sorry could you give a page reference for that?
My understanding was the charcoal was very fine in ADE,Terra preta?