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terra preta questions

 
                                      
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Hey every-body,

When i searched for terra preta on the forums i had some hits but it seemed to all be in other related topics. so i felt like starting a topic just about terra preta.

cos i have some questions that keep running through my mind.

and i hope that there's people here who can explain more about it.

so as i got it from the people who told us about it:
its this super fertile and healthy soil they discovered in the amazon, that apparantly has been build hundreds of years ago by indeginous people using charcoal, (human) feaces and other organic materials.

the charcoal is supposed to retain more humid and micro-organisms. but, and than im lost, is so good in doing this that is increases without human intervention and using this soil means you never have too manure anymore....

What does that mean? without mulching? these people made it appear as if you could garden/produce in it indefinitely without ever having too fertilize or add anything. Using really advanced permaculture(or comparable) techniques i can see that work. just making the conditions for the natural cycles optimal sounds sensible, and possibly truly sustainible, as in close to being perpetual.

but if they really mean conventional/organic gardening without mulching or any other natural ways of improving the soil they really lose me. Because lots of nice micro-organisms is sweet, but they need organic matter to break down in available nutrients for plants to grow.

And i can understand that charcoal in the soil keeps nutrients longer without leaching, and water i presume. I can get that terra preta will enable you to grow for much longer, and would make your (soil)system more efficient.

So anybody familiar with the subject? the last people i spoke to couldnt really explain it to me, and were not interested in the science behind it, but i am. i want to know all about the processes behind it. so this last conversation was very frustrating.

somebody?
grtz
 
                                
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I know we have discussed it before but couldn't find much either. Maybe someone will chime in.
 
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there is a lot about true terra preta that we do not know about. for  example, its ability to "grow" back after being harvested. some south american natives, come in and harvest the topsoil. say the terra preta was 6 ft deep before they took any soil. now say they take 3 ft of the terra preta. whats amazing is in a few years they can come back and there will be 6ft of TP because it grew back. there is still so much to learn about it.

but as far as adding charcoal to the soil in my climate i highly recommend it, not only does my soil hold more water later into the summer, it holds fertility, actually builds fertility, makes the worms multiply like crazy, make plants grow better period and much more.
 
                                      
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this is what i get, superfertility, and regenarative abilities, ok.

but it seems to me that this is not completely new. i mean nature has this ability of building soil, i can get that we can accelarate this by adding charcoal and feaces once. BUT soil without vegetation (or added organic matter for carbons nitrogens etc.), cannot build soil out of nothing.

if you look up the thermodynamic laws, a set of natural laws that are on the basis of science.
(we actually got this in a pdc in germoney, but we also got the terra preta thingy, which contradicts each other as far as i get it)

its just not possible to create stuff from nothing, those microorganism in the soil that make soil out of organic matter still need organic matter (energy from the sun caught and stored by plants). its almost as if a perpetuem mobile in nature is found. the impossibility of perpetual movements is one of the things that the second law of thermodynamics states.

and i dont want this to become some scientific bladiblah, science isnt everything. but, i would like to know if this perpetual thing is just a misinterpretation of a great soil concept, or if the story of terra preta is actually based on such an assumption.

so im hoping for anybody who knows more about it?
cheers
 
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well i don't know much about the TP but I do know that char is a great benefit..i have been using it now for a while in some areas and it has great fertility
 
pollinator
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There is so much leaching in the area, that it is a real struggle to maintain nutrients, even when all locally-used nutrients are returned to the soil. The leaching is so extreme that all lime and silica sometimes wash away, leaving a high-grade aluminum ore.

What would be a closed loop in a lower-precipitation climate (like Europe) is an open loop in the rainforest, because plants can't grab all the nutrients in time. With terra preta, you still have to manure, but you don't have to go foraging for outside sources of fertility as you would if you farmed on the natural soil.

Two components that are often mentioned in the literature, but haven't yet been mentioned in this thread, are fish bones and potsherds.

Another thing I'd like to reiterate, is that terra preta seems to have been made from a low-temperature charcoal. Methods that would produce a good fuel, may result in too-thorough pyrolysis in terms of what's best for the soil.

The regeneration makes some sense to me. Low-temperature pyrolysis has a similar residue to slow decomposition, and nutrients flow through a vibrant rainforest ecosystem so rapidly that the soil would probably have a lot of good stuff fall onto it over the course of a few years.

I'm certain that this is not a recipe for violating the laws of nature.
 
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soil wrote:
there is a lot about true terra preta that we do not know about. for  example, its ability to "grow" back after being harvested. some south american natives, come in and harvest the topsoil. say the terra preta was 6 ft deep before they took any soil. now say they take 3 ft of the terra preta. whats amazing is in a few years they can come back and there will be 6ft of TP because it grew back. there is still so much to learn about it.



And they will sell you all 6 feet of it for only 1.5 times the price .
 
Joel Hollingsworth
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Emerson White wrote:And they will sell you all 6 feet of it for only 1.5 times the price .



I'm not sure I get it. You're implying that it's a scam?

The business model is, unquestionably, one of extracting nutrients from the forest, and selling them to gardeners. The anecdotes of soil regeneration weren't originally part of a sales pitch, they came from academic types interviewing the people who sell the stuff.
 
Emerson White
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Joel Hollingsworth wrote:
[T]hey came from academic types interviewing the people who sell the stuff.


A good salesmen never stops.

Tera Preta gets its dark color from charcoal, charcoal does not reproduce itself, it must be made at high temperatures (think at least 400 F) there for it is impossible for the tera preta to grow itself. It can be mixed in with other, inferior, soils and produce a fairly dark soil that could be sold as tera preta if you had the right salesmen hustle. some of that mixing would happen naturally too, roots can push the soil around a bit underground a they grow, but charcoal and pottery shards do not reproduce themselves,

 
                                      
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yeah, i guess im just trying to filter out the known features of terra preta from all the boosted up story's from the ones who sell it.

and the things joel mentioned,  comes closer to what i thought of it:
fertilizing still necessary but the soil capacity to retain water and nutrients is improved.

indeed, thinking about the tiny topsoil layer of rain forests and the constant run trough/cycling of nutrients and energy, versus the deep top soil we enjoy here in europe its advantages could be limited here...

thanks for your comment joel.

i do tend to think a big part of the story as it reached me (through attending a pdc in germoney) is way boosted, i guess by people selling it. as in my opinion is every perpetual growth story.

selling terra preta is not necessarily a scam, although i wouldnt sell amazon forest soil. i guess nothing wrong trying to sell newly made terra preta. or trying to learn from such a successful method.

but if u ask me some stories are boosted, and (wrong) assumptions were presented as facts. anywho i will first read up on the claims of companies selling this before making such bald a statement.

does anybody has any knowledge on how much to ad to your soil. how much char compared to manure and/or fish remainings? also what type of charcoal is good. i guess regular bbq packs are no good?

It sounds like a good way to improve our sandy, dry and leaching soil on the urban building site we are gardening here.

thanks
 
Joel Hollingsworth
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Joop Corbin - swomp wrote:how much char compared to manure and/or fish remainings? also what type of charcoal is good. i guess regular bbq packs are no good?



Briquettes have a binder in them, and can be way outside the mineral content you would want.

As I mentioned above, good fuel will probably be overcooked as a soil amendment. I've read it still works OK, but not as well. I make my own, and crush it.

I don't know how much charcoal to add, because I don't make nearly enough relative to the amount of compost I make. If I suddenly had a surplus of charcoal, I'd do some trial-and-error as follows: start a compost pile with somewhat fewer browns than usual, and enough charcoal to be significant in the decomposition process but not enough to stifle activity, based on my intuition of how compost tends to go. Something akin to the Indore method or biodynamic methods, but with charcoal as a more-potent replacement for lime & soil. Given enough starting material, I'd make a few piles with different mixtures. In a few months, I'd turn them and see how it all went.

Emerson White wrote:
A good salesmen never stops.

Tera Preta gets its dark color from charcoal, charcoal does not reproduce itself, it must be made at high temperatures (think at least 400 F)...charcoal and pottery shards do not reproduce themselves



I hear you about potsherds not re-generating, but highly-stable organic matter does. Lignite, humic acid, partially-pyrolized wood all end up resembling one another in color, bulk chemistry, and even surface chemistry. Even though they take different paths, the same thermodynamics determines their beginning and ending points.

If I were in the business of growing things, and was told that a product I'm in the market for could re-produce itself rapidly, I would be inclined to buy less of it, not more. Maybe I just don't understand salesmanship.
 
Emerson White
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On the marketing I think that Jevons paradox comes into play, while someone with a fixed need to fill might buy less (for a higher price) there are also people who are willing to buy more to fill a bigger need and people willing to buy any at all because they see it as having a higher value. Additionally how would you know that it was 6 feet deep originally if you only dug out the first three feet? Perhaps they dug a test hole to see how deep it was but that would only tell them about one location, it would tell them nothing about the whole field.

As for it growing itself, I'm not sure about the chemistry. To my knowledge the char in tera (one "r" or two?) preta works just like the activated carbon in an aquarium, forming covalent bonds with more volatile organic compounds and holding onto them, the surface chemistry would in due course trend towards that of the organic compounds that are being bound on the surface. It captures those dissolved organic compounds and the enzymes that the bacteria have released to break them down no longer fit onto them and it allows them to stay in the soil, so I could see the mass of the soil increasing over time as plants grow and die and roots rot apart in the soil, but I would expect a few milimeters over 25 years, not a few feet. In really sandy porous soil with good agitation you might see a few inches. Furthermore if tera preta were able to grow itself why isn't it all over the amazon by now? Everywhere that a camp has ever been set up there are high nitrogen scraps with charcoal, fires happen in the Amazon on occasion I would imagine, at a rate of an inch and a half a year I'd expect the whole of the amazon basin to have been converted thousands of years ago.

I just don't think that there story makes much sense, and I've looked at the problem from a few different angles as you can see. Do you see what I mean?
 
Joel Hollingsworth
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Emerson White wrote:I just don't think that there story makes much sense, and I've looked at the problem from a few different angles as you can see. Do you see what I mean?



I do see what you mean. And in principle, I tend to agree.

I think the growth rates in the anecdotes wouldn't be sustainable long-term, as they would be drawing on local sources of nutrients. A surrounding jungle can replace what hand labor can remove from one isolated spot, over the course of a couple years. The reserves embodied in the large deposits of terra preta we see today are widely acknowledged to have been built up by importing marine products and carefully conserving locally-harvested resources over the course of several centuries, and on the scale of an entire civilization.
 
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Yes , Terra Preta (TP) soils do grow back.
Landscapers harvest only a few inches and because of the bioturbation of all the Wee-Beasties in these six foot deep black soils they grow back at record rates compared to normal topsoil growth rates.


A Recent paper by C. Steiner adds More logs on the Research pile for our Non-Combustion fire.
We can add major savings of N, in Poultry litter composting with Char shows that 50% of Nitrogen is conserved in the compost-Char finished Compost!!

Also Among the concomitant benefits  Julie Major's Ca and Mg nutrients result ;

A new article from Dr. Julie Major's PhD dissertation, out online. Reports on a 4-year field trial set up by Marco Rondon while at CIAT. Shows maize yield increases and improvements in soil fertility.

Maize yield and nutrition during 4 years after biochar application to a Colombian savanna oxisol
http://www.springerlink.com/content/n073641q14661246/

and beyond  that are the several value streams that chars may be called to duty for and thus different valuation. These ecological services also cross over with the usual Ag/soil benefits.

Soils and sediments;
in situ remediation of toxic agents, and the list is long; Heavy metals, Dioxins, Over dosed pesticides & herbicides, In fact I was just contacted by my local Dupont facility, with historic mercury problems, and sent them the recent ISU presentations and other papers on this application.

Feed Rations;
Again a cascade of benefits through the system,as it were;
GHG reductions,  reduced animal Ammonia respiration in confinement thus better feed conversion & general Health thus less antibiotics, Darker litter that easier to sell, or with ranging animal free char spreading.


Suffice to say, that there are a plethora of ways to skin this Biochar Cat.


US Biochar Conference at ISU;
To access the presentations, go to:  http://www.biorenew.iastate.edu/events/biochar2010/conference-agenda/agenda-overview.html, and click on the title of the session you want.


Biochar Sorption of Contaminants
http://www.biorenew.iastate.edu/events/biochar2010/conference-agenda/agenda-overview/breakout-session-5/agriculture-forestry-soil-science-and-environment.html



Dr. Lima's work;
Specialized Characterization Methods for Biochar
http://www.biorenew.iastate.edu/events/biochar2010/conference-agenda/agenda-overview/breakout-session-4/production-and-characterization.html

And at USDA;
The Ultimate Trash To Treasure: ARS Research Turns Poultry Waste into Toxin-grabbing Char
http://www.ars.usda.gov/IS/AR/archive/jul05/char0705.htm


Much More on this Biochar Soils Thread posted in Permaculture;

https://permies.com/permaculture-forums/4693_0/permaculture/re-biochar-soilshusbandry-of-whole-new-orders-amp-kingdoms-of-life
 
Emerson White
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I'm sorry if you posted it, but do you have any litterature that shows Terra Preta growing? Is it growing itself or is it making standard topsoil around itself? Are the types of activity that people are doing on it growing the topsoil or is just lying fallow working? I'll believe that people gardening and mixing in compost will improve the soil over time, maybe even deepening it, but to my knowledge it will not have the same composition as TP.
 
Jordan Lowery
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Tera Preta gets its dark color from charcoal, charcoal does not reproduce itself, it must be made at high temperatures (think at least 400 F) there for it is impossible for the tera preta to grow itself.



i was very skeptical of soil "Growing" myself, but its a known fact that it does happen. no one is saying the char itself is reproducing, but somethings going on.

also there is a lot more than just char in the TP soil, a lot more going on than we have pictured.

but i will say in most soils, char will benefit anyone greatly. over the years of using it i have seen it  increase fertility, stimulate biology, increase water retention, and much much more in a wide range of different soils.
 
erich Knight
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Hi Soil ,
yes, no new char has been made, but biotubation brings it up through the soil profile to mix with the new leaf litter during the agreed on fallow time before more TP is harvested.
I havn't seen any papers quantifying this process, just reports of this informal practice by local farmers/Landscapers.


Now this sounds really *Exciting!* a $364K grant from NASA's Space Archeology program, so we will soon know the true extent of TP soils, not just the estimated 11% of Amazonia (size of France) numbers thrown around;

[size=10pt]UNH scientist to estimate pre-Columbian Amazonian population using satellite
imagery
[/size]
Michael Palace, a research assistant professor at the Complex Systems
Research Center (CSRC) within the Institute for the Study or Earth, Oceans, and Space, is an expert in using satellite-borne imagery to study various
aspects of tropical forests. In this project he will use hyperspectral
imagery taken by NASA's Hyperion sensor onboard the Terra satellite.
The Hyperion camera "sees" in 242 spectral bands of light, allowing scientists to identify the chemical makeup of tree leaves, which in turn is
related to nutrients in the underlying soil. The more nutrient-rich leaves
or specific groups of tree species seen by Hyperion will be the signature
for what Palace is looking for – Amazonian black earths – sites containing
soil rich in organic matter, charcoal, and nutrients and frequently
associated with large accumulations of potsherds and other artifacts of
human origin.

http://www.eurekalert.org/pub_releases/2010-06/uonh-ust060710.php

Here is some more back round on the Satellite TP survey and Michael Palace

Time Traveling Via Satellite
Tropical ecologist Michael Palace comes full circle with a NASA Space Archaeology grant to estimate the population of pre-Columbian Amazon indigenous peoples
MICHAEL PALACE majored in archaeology and environmental science at the University of Virginia, then turned to the environmental science side of things as he pursued his master's degree at UVA. For his thesis he studied the dynamics of Costa Rican howler monkeys in relation to landscape-level vegetation structure.

http://www.eos.sr.unh.edu/newsl_0610/palace.shtml

Cheers,
Erich
 
Emerson White
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soil wrote:
i was very skeptical of soil "Growing" myself, but its a known fact that it does happen



I think you are using the term "known fact" a little loosely. I think "Often repeated story" would be more accurate at this point, especially if no one has set up a test plot and measured in a scientific manner.
 
Joel Hollingsworth
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Emerson White wrote:
I'm sorry if you posted it, but do you have any litterature that shows Terra Preta growing? Is it growing itself or is it making standard topsoil around itself? Are the types of activity that people are doing on it growing the topsoil or is just lying fallow working? I'll believe that people gardening and mixing in compost will improve the soil over time, maybe even deepening it, but to my knowledge it will not have the same composition as TP.



My understanding is that non-human activities make topsoil in these anecdotes, especially the re-vegetation of places that have been dug up, and normal animal activities that the plants allow. Topsoil formation is greatly speeded up in the environment fostered by the terra preta. Components of terra preta that are not the result of decomposition get diluted in the process, but the result still does not resemble the surrounding topsoil (at least, not for a few cycles of harvest and fallow).
 
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This is what somebody said about this in another group I'm a part of:

There is a black soil in the Amazon called terra preta - it's a man-made
soil based on years of accumulated bio-char, usually from charing the
spent crops (which is about the only way to keep the jungle at bay too).
As a result, these plots are super rich because the pores in the charred
material are like nutrient batteries, capturing and sequestering
nutrients from the frequent rains before they can leach away.

When I get my greenhouse dug out, I'm going to have the floor scraped
clean. It's pure white sandstone - actually pretty hard sandstone for
the most part, but it breaks up into a powder-fine pure white sand. I'll
have the digger scar the floor with the backhoe bucket to give me a few
inches of sand in the bottom when he's done.

I am then going to start collecting woody weed stems - like those of the
giant ragweed we have growing here, and twigs and such. No big chunks of
wood and no hardwood - too hard to pulverize into a powder. I'll get a
burn barrel and stuff it full of this material and make some charcoal
out of it right where I'll be depositing it. A few barrel's full should
make enough to get me started, methinks. I'll take a tiller and till
that into the pure sand thoroughly, then mix in some finished compost, a
bit of lime and perhaps some colloidal phosphate clay and maybe some
volcanic ash or pulverized volcano sand. And that'll be my new topsoil.
More or less. It'll have to mature - form a soil foodweb. When I plant
trees, I'll dig into the sandstone below the topsoil so eventually
there'll be lotsa little pits in there that'll have sand and charcoal
and compost so that'll increase the depth of the topsoil too.

I have perhaps 8-12" of sand in the bottom of my pit now and outside the
greenhouse enclosure that sits in the pit I have a volunteer basswood
tree and a willow tree that are growing quite happily. I'll have to
remove them, of course - this winter I'll dig them up and heel them over
in my sand-pile while I find a place to plant them. But it is promising
that trees can grow even in that little bit of loose sand. The taproots
may have found soft parts of sandstone to snake down towards the
water-table too. I expect my tropicals to perform similarly. Hopefully,
with them tapping into the water-table just 8' below the bottom of the
greenhouse, I won't have to water as much. That'd be convenient. Of
course, I'll have plants in there that don't form deep taproots so
they'll have to be irrigated and I may tap my fish-tanks for that, or
pump in rainwater thru overhead sprayers inside the greenhouse whenever
it rains and fills the rain-bucket from the gutters - a simple sump-pump
with a float-switch would do that automatically. Ooh - that's be an easy
way to foliar feed with humus tea and whatnot too - just switch off the
pump, brew humus tea in that same barrel (worm castings, a bit of
molasses and lotsa aeration) for 24 hours, then switch on the pump and
watch it spray my plants happy.

Anyway - converting pure sand to terra preta will be an interesting
experiment. I'll keep the burn barrels and keep adding char to the
greenhouse over time to build it up good. I guess I'll probably want to
add char into the bamboo bed that'll be growing up topside too...

But I soooo look forward to fresh avocados, oranges, macadamia nuts,
cherimoya, coffee, chocolate, vanilla, piper-pepper, guava, pineapple
and much more from this new soil...

I guess I'll need to have large flaps on either end of the hoop-cover to
open so that bees can get in and out on nice days. The glazing may be
clear, so hopefully they'll be able to navigate easily enough to the
large openings rather than bumping hopelessly into the glazing - but
even then they should be able to get out easily enough. My avocado has
been flowering in the early Spring when the bees could be pollinating it
but it's been too cool to remove the cover altogether - but warm enough
that large vents on either side can be opened. I can cover the vents
with chicken-wire to keep out birds and critters. My orange has flowered
too but it doesn't need a pollinator, fortunately - tho surely it'd
benefit from one. My coffee will need pollinators tho. Maybe I'll bring
in some mason bees into the greenhouse too... Ideas ideas - I so look
forward to digging that out more and expanding it. My wife getting
permanent work will help enormously and that will happen very soon.

Be well,
Mike

from http://www.taroandti.com/ Exotic Plant Info and More...
 
Denise Lehtinen
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Also you don't want to use store bought charcoal... it has nasty things in it.

The simplest way to make charcoal is to burn wood in an oxygen deficient environment.  Any campfire (at least the ones I make) always makes some of it.  I've been making mine in a small grill with a cover.  Get the fire going and put the lid on.  I can only make very small batches this way, but it is easy to do.

The simplest way I've found to turn it into a powder takes a page out of how some women in Africa make flour.  Their method consists of a big old heavy ceramic jug and a big old tree log that is wider on the bottom to pound it with.  My method uses a ceramic flower pot without any drainage holes in it, and a stick from one of the weedy trees around here that I was going to make into a handle for a home-made sidewalk edger.  In both methods you get to do the pounding standing up -- which is nice.

The charcoal works by absorbing the nutrients that fall on it via the rain, etc.  This ability of charcoal to absorb nutrients is also used medicinally as a treatment for some forms of poisoning.  You'll find it sold at your local drugstores for that purpose.  So, it isn't at all new that charcoal has this ability -- it is only new (to most of us) that that can be used to advantage in building soil fertility.

 
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When I was a small boy I spent a lot of time with my old style farmer grandfather (one of the greatest influences in my life). One day we were in a field and he would pick up bits of earth and taste it. When I asked why he did that he said he wanted to know if the soil was sour or sweet, and this soil was sour and needed to have charcoal added to make it sweeter.

When I first read about biochar a while back I asked a biochemist who I know what might be happening with something as inert as charcoal de-acidifying (sweetening) the soil. Without missing a beat he said it gave off carbonate ions which neutralized the acid. I wonder if this isn't the largest part of the success of biochar.
 
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Biochar is pretty fascinating stuff and I would like to give my best guesstimation of what is happening. After watching the video, “The Secrets of El Dorado”

http://video.google.com/videoplay?docid=8993313723654914866#

I am convinced that the Terra Preta formations are part of a classic ceramic pit fires, similar to Raku firings. Before there where kilns, primitive ceramicist would have dug deep holes filled the hole with their pots and started the fire.

http://www.eos.sr.unh.edu/newsl_0610/palace.shtml

Look at the third picture (thank you Erich) I’ve never seen this picture before, but I think it supports my Hypothesis. The blackened soil is contaminated with the pit fire smoke, burnt organic material and ash. But notice the lighter brown soil, which suggests the foot print of where the greenware pots were stacked.
There are four large black footprints, located in the hole that shows where the burning took place. Because the Amazon is so humid the greenware clay body would have retained a lot of water. So the firing would have to start out at a low temperature. The pit temperature couldn’t rise above 120 degrees, the boiling point of water. Otherwise the side of the ceramic pot would get a steam explosion and blow out the side of the pot. The pot shards would blow into the fire and continue to pop until they either became smaller and smaller pieces or the water evaporated out of the clay body. The remaining parts of the exploded pot would have dried out and acted like a bag wall or a buffer wall to protect the inner stacked pots from a sudden rise in heat.
What I’ve read, there is a far amount of burnt rock also found in these formations. With a learning curve, I would think that large rocks began to be used as bag walls and avoiding the loss of the first roll of pots.
Once the clay body water has evaporated out the fire and temperature can be increased. So how do you know if the water has evaporated out? Are the pots no longer exploding. In a modern kiln you sniff at the glory hole, it smells acidic until the water is removed. (Ok Paul, I might get cited, but these are ceramic terms) You can hold a mirror about the glory hole with the glass facing down, steam will condense on the glass if there is still water in the kiln. It could have been as simple as putting a piece of organic material like moss on the top of the pot stack and wait for it to dry out and turn brown. I didn’t know.
The fire is built up until 600-850 degrees has been reached in the pit. Now the temperature has to be maintained until the molecular water has time to evaporate out of the body and the clay body can go through quartz inversion. Again if the molecular water boils at the higher temperature there will be a steam explosion. So again it would be important to protect the ceramic works with a stone bag wall. See above method of predicting when the clay body water has been removed, it similarly applies to the molecular water.
After the molecule water has been removed, wood and other organic materials would be added until there was a huge blaze bring the temperature up to I’m guestimating 1100-1800 degrees. But I would think more towards the lower temperatures, judging from what I’ve seen from museum pieces.
Now the biggest danger is from crushing the pots, when throwing wood onto the blaze. The fire would be allowed to burn itself out or soil could be thrown on top to snuff out the flame and help hold the temperature in the fire pit. After the pit had cooled, the soil, pot shards, charcoal and ash would have been thrown out of the pit to retrieve the whole pots.
As the ceramic community began to create the next batch of greenware, human nature tells me that the open pits would have been used as a trash pit, which would explain the bones and a mixture of organic materials.
When the pit fire site was finally abandoned it would have filled in with organic forest materials to create the rich black soil we see today. But that’s my hypothesis.
FYI
I few years ago I was watching a ceramic teacher, going through his stack of ceramic mugs that had just come out of a firing. They all looked fine to my eye, or at least useable. But he was smashing everything that wasn’t perfect. I wonder if human nature wasn’t the same with the ancient pit fire artists.

Many years ago the ceramic department took the students out to a cleared area, off campus to do pit fires and raku. The students were sitting around all night maintaining the fires and noticed the smoke was coming out of different locations in the ground not associated with their firers. They later found out that the area was a wooded forest that had been bulldozed down and covered with dirt. All those underground trees caught fire and were spreading underground. The fire department spent a week trying to put it out.






 
erich Knight
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I tend to agree with BiologyBill,
Moira Wilson of the University of Manchester has developed a ceramic dating technique which sounds perfect to draw an exact time line of TP development year over year.
At an accuracy of years we could see the speed at which the system built on itself once initiated.
Archaeological dating by re-firing ancient pots - physicsworld.com
http://physicsworld.com/cws/article/news/39413

My reviews of the agronomic field trials & literature using Biochars clearly show consistent positive effects in temperate & tropical soils, what is not known, and in debate, are some of the mechanisms for the "black box" nature of biochar effects : MYC / AMF & microbe refuge theory, Glomalin soil aggregation & water films, microbial mats & quorum sensing, expansion of aerobic soil horizons & suppression of the anaerobic. As a feed ration for livestock & aquaculture; http://superstoneclean.com/video-presentations/
and the most startling, plant chemical signaling for expression of dormant genetic traits.
http://terrapreta.bioenergylists.org/content/trials-maize-reactivating-dormant-genes-using-high-doses-salicylic-acid-and-charcoal

I sent DuPont work with heavy metals last year which initiated field trials Hg showing a 95% reduction of food web uptake! Their lab bench results showed good binding, but did not hit 95% reductions until the in situ study with the full complement of microbes, fungi and the bioturbation's of macro fauna.

This same problem remains for explanation of the mechanisms of other char applications, The internal biology changes when char is used as a feed ration, The role of Phosphorous chars for both plant availability and an heavy metal binding remediation techniques. The intricacies of fostering increased aerobic conditions into deeper soil horizons, I'm just so glad we have all these positive affects that tantalize
researchers and will build funding support to answer the mechanism questions.

What the CFC / Ozone success story was for raising the importance and attention to atmospheric chemistry, I feel biochar soils will be for carbon soil chemistry, Mycology and Microbiology.

So Much work to be done,




The Terra Preta Prayer

Our Carbon who art in heaven,
Hallowed be thy name
By kingdom come, thy will be done, IN the Earth to make it Heaven.
It will give us each day our daily bread and forgive us our atmospheric trespasses
As we forgive those who trespass against the Kyoto protocols
And lead us not into fossil fuel temptation, but deliver us from it's evil
low as we walk through the valley of the shadow of Global Warming,
I will feel no evil, your Bio-fuels and fertile microbes will comfort me,
For thine is the fungal kingdom,
and the microbe power,
and the Sequestration Glory,
For ever and ever (well at least 2000 years)
AMEN
 
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It's the housing estate for a diverse range of multi cultural microbes its has fulcatative, anaerobic and aerobic microbes of various varieties.

Watching the below video made me obsessed with doing my own, they still let nature run it's course with mulching, they also let it rest for years before they harvest and sell terra preta soils in the Amazon.

If that doesn't load, it is called terra preta the secret of Eldorado



Keen to hear what you think if you watch it.
 
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Only just came across this thread.

erich Knight I love your Terra Preta "Prayer" a fitting comment to this thread and all soil improvements in general, thanks for the laugh.
 
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Joop Corbin - swomp wrote:

the charcoal is supposed to retain more humid and micro-organisms. but, and than im lost, is so good in doing this that is increases without human intervention and using this soil means you never have too manure anymore....

What does that mean? without mulching?

...

And i can understand that charcoal in the soil keeps nutrients longer without leaching, and water i presume. I can get that terra preta will enable you to grow for much longer, and would make your (soil)system more efficient.



Hi, I can provide some explanation of the chemistry involved in charcoal as a soil amendment and the differences between temperate vs subtropical vs tropical soils which should shed some light on terra preta.



Plant matter is generally mostly water by weight and, under a microscope, has a complex structure of various cell types arraigned into layers and those layers arraigned in different shapes and patters depending on the plant source, be it grass, herbaceous perennial, palm, bamboo, or woody plant. Density is highly ununiform and there are a lot of different microscopic and macroscopic structures. Once pyrolysis occurs, the water is mostly evacuated and the former cell walls and structural components make up the bulk of the remaining weight, along with small amounts of trapped ashes and tar like residues. In addition to the pre-existing venation, porosity, an cavities in the plant matter, pyrolysis leads to extensive crack propagation as steam produced inside the drying and hardening plant tissues causes ruptures, as well as the shrinkage from the drying itself causing buckling and checking.

The end result is a material that has a very complex structure with a variety of porosities ranging from microscopic to macroscopic.

Chemically, the material is roughly speaking an amorphous carbon species with substantial impurities. Incomplete dehydration, dehydrogenation, cracking, and similar reaction processes mean that rather than sheets of pure carbon like in graphene, there are a whole bunch of different residual organic (in the chemical sense) molecules. In areas of more complete reaction processes leave behind graphitic masses, vitreous carbon, and even fullerenes sometimes. To some degree there is also some carbon black and soot content. The degree of pyrolysis and the temperatures and durations involved will lead to a variety of polycyclic aromatic hydrocarbon (PAH) levels, and similarly a variety of carbonyl, carboxyl, and other functional group levels. All of these aromatic hydrocarbons and functional groups provide bonding sites and increase the ion exchange capacity (mostly CEC, but also AEC).

Typically, the charcoal is then broken up into large particles somewhere between coarse sand and pea gravel in size. At least when people are making "biochar" anyway.

What you're left with at the end of all that are these particles that with low weatherability and degradability that are highly porous with excellent internal and external drainage and a fairly high CEC.



Now let's talk about soils.

The formation, composition and behavior of soil is highly climate dependent. To the point where, basic "common sense" notions that are true in one region are false in others. As a great example of that, and as an intro for why charcoal can be useful, we can talk about soil organic matter.

As plant and animal detritus break down in the soil, the easily destroyed materials are quickly used up, leaving behind whatever materials are more difficult to break down. This is typically lignins, oils, and waxes, and some amount of highly complex carbohydrate structures. After some time, these structures tend to form what is loosely called "humic substances." This is an absurdly broad category of chemicals which can generally be said to be the soil organic matter component that is to some extent resistant to microbial activity. In soil science, they are broken down into three rough categories depending on molecular weight and solubility in alkalis and acids, fulvic acid, humic acid, and humin. It's very important to note that these three are not individual chemicals or made of specific molecules, they are just broad categories for describing residual organic matter in soil. You basically have these big, high molecular weight complexes of phenolic rings, quinones, polysaccharides and long-chain carbohydrates, etc. all stuck together. Typically, in heavy soils these macromolecules will form colloids with the clay particles, where the outsides of lumps of humic subtances will have clay particles stuck to them, whereas in lighter soils they will be adhered to the sandy particles. Imagine pouring tar into a container of flour or a container of tennis balls if you will to get an idea of the difference there.

These humic substances also tend to have lots of aromatic rings, different functional groups, and in general lots of bonding sites, so they have a high CEC. They also can both physically hold or trap water and can undergo hydration and dehydration reactions and so chemically hold or release water. The "sticky" effect described before also tends to increase the porosity of the soil's mineral content to some degree. Finally, they are described as resistant to microbial decay, but just resistant. Granted, dead microbes can also contribute to soil organic matter to an extend, partially closing the cycle, but not entirely. Over time, soil organic matter is converted to CO2, which diffuses out of the soil and blows away in the wind. Some amount is also lost via leaching as water soluble low-molecular weight compounds dissolve into water and are washed away. Absent new depositions of animal and especially plant matter, the soil organic matter will eventually all, or nearly all, dissipate into the atmosphere. If you place a container of dark garden soil somewhere it will have some water percolating through it but remains oxygenated, and most importantly stays warm and moist, and you prevent any plants or algae from growing in it, that nice dark garden soil will over a few months or years degrade into just plain mineral soil with almost no organic matter.

If the container is warm and wet enough, the breakdown of soil organic matter will actually occur fast enough that new plant and animal matter will struggle to replace it, with new matter getting mostly broken down quickly. Since higher organic matter levels means more microbial activity, the equilibrium point isn't 0% but something a little above that, as microbial activity dramatically slows down once you get to very low soil organic matter levels.

If you do the same experiment but increase the temperature and water flow, ideally under somewhat acidic conditions, even a lot of the mineral content will leach out and you'll be left with just aluminum silicates, iron oxides, and a few other highly resistant, highly oxidized minerals. And that's basically how you get Oxisols (wet tropical soils) and, in less extreme cases, Ultisols (southern red clay).

Now let's put that all together. For soils that are fairly dry and generally cold, but that support, for example, highly productive grasslands that quickly produce new organic matter and quickly deposit it in the soil, the equilibrium point for the soil organic matter will be very high, maybe as high as 15%. That's how you get Chernozem. Eastern Ukraine and southern Russia are almost semi-arid, and are bitterly cold with fairly short summers where the soil takes a long time to warm up, especially given the weaker sunlight at those high latitudes. It's basically the perfect conditions for maximizing plant matter deposition and minimizing soil organic matter loss. The warmer and wetter the soil, and the shorter the winter and faster the soil heats up, the lower the soil organic matter equilibrium point will be. In the wet tropics, that equilibrium point is barely above zero, in the wet subtropics like the US South, it's oftentimes only 1-2%. In cold temperate regions, it can be higher, perhaps up to 5% or more. Soil texture plays are role as well, since clay colloids can protect the soil organic matter longer term compared to the humic substances adheared to sandy particles that are completely exposed to microbes, water, and oxygen.

This of course dramatically alters the effectiveness of artificially raising the soil organic matter content (e.g. adding compost or mulch). In traditional New England gardens, which are moist but cold, or in classic West Coast gardening areas like southern California and the inland PNW and Mountain West, which are summer-dry and have relatively long, cool winters compared to similar USDA zoned areas in the rest of the country, artificially raising the soil organic matter content is highly effective at increasing fertility, since the natural equilibrium point is fairly high and the breakdown rate is quite low so even if you push the soil well above the normal equilibrium point, it will take a very long time for it to adjust back down to more natural levels. In contrast, someone gardening in Florida could theoretically have all artificially added soil organic matter decomposed and leached/blown away in the wind within a single growing season. Having grown up on an organic farm in eastern NC with sandy soils, as a teenager I never understood why we could apply compost and goat and chicken and cow manure to the garden over and over and over for more than a decade and mulched everything as thick as we could and still the soil was just this deep sand that retained its pale, infertile color and never developed that dark color and earthy smell we were promised by all the gardening books (written by folks in Maine, Idaho, or the UK...).

Now I know. All that organic matter was just blowing away in the wind a few weeks to months after we added it.



There are a few other equilibria that need mentioning.

People often talk about microbes being supported by soil organic matter and how as they consume that organic matter they release nutrients for plants to take up. This is technically true, but it misses the main part of it. Far and away the most important thing organic matter does, once it reaches the more decomposed stage, is it provides a medium for growth and nutrient holding and a buffer for moisture. The lumps and sticky masses and films of organic matter are in a lot of cases just providing surface area for microbes to live on as well. It is also being broken down and consumed by some soil microbes, yes, but the vast majority of soil microbes are simply living on and in it, not consuming it. Indeed, the vast, vast majority of soil microbes can't even eat organic matter anyway. Instead, those microbes are doing whatever it is their kind do, be it reducing sulfur, oxidizing sulfur, solubilizing phosphate, absorbing soluble phosphate and making it insoluble, reducing nitrites to nitrates, reducing nitrates to ammonia, converting ammonia into nitrates and nitrites, denitrifying nitrates into nitrogen gas, fixing nitrogen gas into nitrates, turning living potatoes into mushy dead potatoes, fermenting alcohols and lactic acid, etc. Notice how most of these chemical activities are cyclical? (Also, notice that the soil itself fixes nitrogen? Yeah, it's not only legumes, and the dozens of non-legumes nitrogen fixing genres of plants that for some reason never get any love, just regular dirt will fix nitrogen all by itself, it's just that the equilibrium point might not be as high as if there are plants pumping sugars down to feed microbes doing the fixing, but regardless, soil, unless completely sterile, will never actually run out of nitrogen--though it can get pretty darn low). Depending on the species and the conditions, the soil microbes will be running these reactions one way or the other, or in reality both ways, with some equilibrium point depending on conditions. And plants are part of those cycles, because they're doing things like uptaking soluble ions, secreting sugars, dying, releasing highly digestible forms of organic matter, etc. Most plant roots, for example, are primarily made up of cellulose, and cellulose degrades in the soil due to the activity of certain microbes that enzymatically break it down into disaccharide and further down into just simple sugars. Which means that little or even no humic substances might result from a plant root dying and being consumed, for example. But that process will still cycle some carbon, and more importantly cycles sugars into the soil as well as organic forms of mineral nutrients, which will eventually get consumed and turned into inorganic forms, which plants then pick back up. And the humic substances, because of how well they moderate water and how well they chemically bind ions, as well as provide pH buffering and such, really help keep conditions favorable for microbial activity and provides a reserve so to speak of chemicals in the soil that's constantly getting added to and removed from.

So a phosphorous ion might get chelated by some phenols and just hand out in the soil for a while, then gets picked up by some bacteria that uses it in a cellular process but then gets eaten by something else that gets eaten by a fungus which passes it over eventually to a plant that uses it in a leaf that gets eaten by a bug that dies and gets eaten by ants and ends up in an ant that gets killed by a fungus which eventually decomposes and passes to a bacterium that secretes it as part of a biofilm in the soil where it adheres to a grain of sand for a few more months before another bacteria comes along and breaks down the organic compound that it was part of and then releases the phosphorous ion as a salt again which begins leaching during a rain storm but then binds to some organic matter in the soil for a while until the soil temperatures change which alters the pH and releases the ion which gets taken up by a plant root directly and... etc. Sure, there are also some phosphorous molecules bound up deep in a tar-like lump of humin stuck to some clay, but that phosphorous doesn't enter the cycle until that humin gets oxidized and broken down, which might be months or even a few years later, or never in a bog with no oxygen. Most of the nutrient, energy, and water cycling that's happening in the soil is taking place in conditions provided by degraded soil organic matter, but it's not from the final decomposition of degraded soil organic matter. Perhaps think of a very tall glass of water. You can scoop a spoon of water off the top and into another cup, put the water back, and repeat over and over. Eventually, the water at the bottom of the glass will also get mixed up and ends up at the top of the glass where it gets scooped up, but it'll take a very long time. It's the water at the top of the glass that's doing the most cycling.

But of course there's also an extent to which stuff degrading in the soil doesn't just get consumed and does form more resistant chemicals. Stuff with more lignins and waxes and whatnot ends up in the soil and a lot of that ends up contributing to the more long lasting forms of soil organic matter. But just as that stuff is being deposited, mostly by plants and animals, some microbes, and just free oxygen, is steadily breaking it down and turning it, ultimately, into CO2 that just floats away same as the sugars from the faster cycles that get metabolized into CO2 and diffuses off into the atmosphere. The first process depends mostly on the primary productivity of the plant life on top of the soil, and how quickly it's getting cycled into the soil (hence why grass is such a big deal), but the second process is mostly just a function of how much soil organic matter there is, how warm the soil is, and how moist but still oxygenated the soil is. So, to bring back the comparison mentioned above, cold temperate grasslands have great primary productivity, at least in summer, and put out a lot of organic matter that ends up on or in the soil that same year or even just a few weeks later, but the soil is either frozen or cold most of the year, and once it does finally warm up, is generally also at its driest since most temperate grassland regions of the world have relatively dry late summers. Hence the black dirt of the American and European prairies. Reverse that, and make the soil warm and moist almost all year, and it won't matter how fast the plants are growing, the soil microbes will be destroying most of the soil organic matter as fast as it arrives.

But then, with very low levels of soil organic matter, an issue arises. Soil particles, the mineral component anyway, are chemically pretty inert, and they tend to have low porosity and so don't hold air or water inside, just in the spaces between the particles, and they don't provide much pH buffering, hydrate buffering, salt buffering, etc. Clay particles and more weatherable minerals tend to be better, but they're still not amazing at these things. Sand particles tend to be pretty bad at it, and also just don't have much surface area for anything to happen on. And if the soil is extremely weathered and it's just some extremely chemically stable minerals left, then the soil is going to be almost inert. When that happens, leaching becomes a major drain on the system, and so many of the nutrient and energy cycles described above end up with low equilibrium points. Additionally, the soil itself will cycle much faster between too wet without enough air, to too dry, the pH can swing more rapidly or slide to more harsh extremes, and in general conditions just aren't as good and are much more chaotic. Hence the problem with tropical soils, and to a lesser extent with subtropical soils.



We can finally come back to charcoal.

So what's the selling point of charcoal? Well, it has all the buffering, nutrient holding, water and oxygen storing, and related benefits of regular soil organic matter, and has high surface area via its wild porosity and so can provide a lot of media to grow on. But unlike soil organic matter, charcoal is extremely stable in the soil and has a far, far, far lower rate of degradation and oxidation. Sure, there are mineral nutrients that might be left over still trapped down in a glassy mass of vitreous carbon, just as there can be in humin, but as with the point above, it's not the few nutrients that are trapped in the long-lived forms of soil carbon that matter, it's all the nutrients constantly cycling on the chemical medium provided by those long-lived forms of soil carbon that matter, and all the good conditions it creates by moderating water, oxygen, etc.

There's a few other things charcoal does that are quite nice. Regular soil organic matter has excellent water holding capacity, and to the extent that it causes soil particles to aggregate by basically cementing them together it also improves internal drainage. By making some particles stick together, it effectively makes the soil more coarse than it actually is, and those coarser aggregated particles don't pack together as tightly, which channelizes the soil, allowing excess water to drain through it like it would drain through sand or gravel. But that soil organic matter is still trapping and absorbing lots of water which will then slowly release. This process only works to a point, though, because what happens if you keep adding cement to aggregate? You get concrete, which drains really, really slowly. Basically, there are few channels for the water to flow through because there are sticky masses of soil organic matter everywhere gumming up the works. Hence why boggy soil is so reluctant to drain even when ditches are cut through it. If highly, highly aerated, highly organic soils or media can drain, for example fresh compost, but once it packs down or collapses in on itself, the drainage becomes awful. Organic matter, depending on the form, can also become highly hydrophobic when very dry, and so can be difficult to wet, which also causes drainage problems of a different sort.

This isn't the case with charcoal. Charcoal has excellent drainage, and it retains that under almost any conditions. It works in two ways. Internally, charcoal particles are highly fractured and have lots of cavities, voids, and such that water can seep through, but charcoal particles also tend to be fairly coarse and tend to be very rough and don't pack well, so water also has lots of space to drain around the particles. All that internal and external drainage space also means that it has excellent aeration, and those voids and such mean that even submerged, charcoal will often still hold a whole bunch of air. What voids and such that do end up filling with water will generally be very slow to release that water due to water adhesion, especially since charcoal is chemically active enough that it'll try to hold on to that water through hydrogen bonding, van der waals forces, and a slew of other means. So it has great moisture holding capacity as well.

Which all sounds great, and to an extent it is. But remember that all of this is just providing good conditions for soil microbial life? Build and they will come is only true up to a point. Excellent soil characteristics will hit a wall of diminishing returns and the microbial life and nutrient cycling will end up being rate limited by something other than water and oxygen levels or surface area and CEC or pH buffering. Where is that point of diminishing returns? Depends on the soil, the plants, the climate, etc. It's likely somewhere around the normal soil organic matter content of most healthy, fertile, rich soils, which is between just 3-6% soil organic matter believe it or not. After that point, you're not getting much benefit in most cases.

And that means that in temperate zones where the soil organic matter will already be close to or at the ideal level, adding charcoal is unlikely to do much in terms of soil microbial activity. Unfortunately.

There can be other reasons for using it though. The rough edges and texture of charcoal can be useful for controlling or deterring certain pests, for example. And recall that the aeration and drainage of charcoal are far superior to that of soil organic matter at higher percentages? In some cases, waterlogged or anaerobic soil needs to be avoided at all costs, such as when growing succulents or dealing with disease pressures that occur in those conditions. In that case, adding a large amount of charcoal might tilt the soil more towards those conditions. Add enough charcoal and the soil might eventually get to the point where it's exceptionally well drained while still moisture retentive, to the point where standing water is almost impossible but plants still get plenty of moisture from the soil despite that drainage and oxygen levels remain high pretty much all the time. There's actually a real life soil type out there that's like that. Volcanic soils. It's also highly erodible, and DIYing a volcanic soil garden would mean applying something like six feet of charcoal to the whole thing and somehow tilling it in, which sounds a little unrealistic. So there's that. Chemically they're also not actually that similar but close enough for this example.

That point about drainage though also applies to a related product that is used in bulk to improve soil hydrological characteristics, PermaTill and other expanded slate products, and other more well-known expanded minerals like perlite and vermiculite which tend not to be used in bulk due to cost and other issues.

When it comes to those difficult soils in the wet subtropics and especially in the wet tropics, however, charcoal can have a significant impact on the fertility of the soil because high soil organic matter, the holy grail of conventional organic gardening doctrine, doesn't exist in the wet tropics, and is a fleeting, capricious thing in the wet subtropics. In the Amazon, and in the South to an extent, you have to manure and mulch over and over and over. And within a growing season or so, it's all gone already like dust in the wind or tears in the rain, or in this case CO2 in the wind and solutes in the rainwater. The advantage of terra preta is that it's made of things that are not biodegradable, but that have much or all the benefits of soil organic matter. The pottery, by the way, is similar to the charcoal, though probably a bit inferior since it'll have a lower CEC.

As for terra preta "regenerating" itself, sounds like hype to me. More than likely, it was just that after they scraped the topsoil away, charcoal particles that had been dispersed in the subsoil started coalescing in the new topsoil layer, turning it black again. Charcoal being very light, it will tend to collect near the surface unless buried deeply through some kind of animal or human driven mechanical action. They probably saw a pale subsoil that after a while miraculously "regenerated" the dark color and superior texture and thought the dark materials were somehow regenerating. Almost certainly not, they were just finally not buried in the highly stratified subsoil and could move around again, which mostly means collecting in the top few inches. What may have even happed was there could have been a mineral deposition formed hardpan layer in the subsoil at the aerobic to anaerobic transition point or something, but after they removed the topsoil that transition point dropped deeper into the soil, which enabled all those minerals that were cementing the hardpan to dissolve, loosening the soil and allowing those charcoal particles to move around. Who knows, but among the least likely of options was a chemical process that requires carbon feedstock, combustion, 800 F temperatures, and sudden but sustained oxygen depletion was somehow spontaneously happening in the soil after they scraped off the topsoil...

Charcoal as a soil amendment is already kinda miraculous, we don't need to be conjuring up even more miraculous properties that make a mockery of reason and well-informed good sense.





 
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Outstanding post, Alex Vivaldi!
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