[Terrapreta] More on clay/pottery etc

[Kevin Chisholm]

Dear Sean

Sean K. Barry wrote:
> Hi Kevin and all,
> 
> Well, I just wonder about the scope of the Terra Preta.  It is
> claimed that it covers as much as 10% of the land in the Amazon river
> basin ... equivalent to an area the size of France  That's an awful
> big garbage pit or pile of charcoal fines.  I don't know, but I don't
> think even the whole human population now maintains a garbage pit the
> size of France (unless of course you actually mean "France" ...
> hehe).  It seems to me that the soil was manufactured for use as
> agricultural land.  Maybe it is 4'-6' deep in places because they
> just kept doing it year after year, piling up more on top each year?
> 
> Just a few thoughts ...

And very good ones!! Would it be possible or likely that TP evolved as 
follows:
1: Trees (and other vegetation) toppled in wet areas, creating a carbon 
similar to charcoal, during an uncommonly wet period. The wet areas then 
eventually returned to normal, and people found they could grow crops 
better in "black soil".

2: Then the people started making charcoal on purpose, to be able to 
make black soil elsewhere.

It would be interesting to see if there are pottery shards in all the 
known TP areas, or just some. If only in some areas, this would tend to 
support the hypothesis that the pottery shards are broken charcoal 
retorts. (Or broken smudge pots.)

It would be very interesting to differentiate between "natural carbon" 
and "man-made charcoal." There many areas around the world where there 
is "black soil" deposits that are used for Market Gardening. These seem 
to be simply eutrophied lakes.

Best wishes,

Kevin
> 
> SKB ----- Original Message ----- From: Kevin
> Chisholm<mailto:kchisholm at ca.inter.net> To: Michael
> Bailes<mailto:michaelangelica at gmail.com> Cc:
> terrapreta<mailto:terrapreta at bioenergylists.org> Sent: Wednesday, May
> 09, 2007 4:03 PM Subject: Re: [Terrapreta] More on clay/pottery etc
> 
> 
> Dear Michael
> 
> Heres an "outside the box" thought...
> 
> Is it possible that people had large charcoaling operations, where
> they retorted the biomass in pottery retorts, and simply discarded
> the fines and broken retorts into a dumping area?
> 
> Then later on, someone noticed things growing on the areas where 
> charcoal fines had been dumped, after the Charcoal operations were 
> abandoned.  They would then graze their animals on the grass, and the
>  manure would provide nutrients to support the process.
> 
> Why would the Terra Preta beds be 4' to 6' thick? Farmers are smart
> and observant. In the Olden Days, with no mechanization, they would
> find ways which gave acceptable growing results, with the least
> inputs. It takes a lot of work to build a Terra Preta bed 4' to 6'
> thick, just to grow crops. It does not make sense that they would
> build the Terra Preta beds any thicker than necessary. I would
> suggest that it is simpler to dump waste charcoal fines and broken
> pottery in a low lying spot in the land, than to spread it uniformly,
> than retain the uneven ground surface.
> 
> The above seems to be a more credible explanation for the formation
> of Terra Preta fields. It explains why Terra Preta beds could be 4'
> to 6' thick, when such thickness are not necessary for growing crops.
> 
> 
> So, I would pose the following hypothesis for your consideration:
> 
> 1: In the past, charcoaling operations made charcoal in pottery
> retorts.
> 
> 2: The market was for larger pieces of charcoal, so they screened out
>  the fine charcoal and discarded it, simply by dumping on the ground.
> 
> 
> 3: Similarily, when the pottery retorts were damaged or broken, they
>  would discard them in the same areas where they dumped charcoal.
> 
> 4: They would favor low depressions near the retorts, in that they
> would hold a lot of charcoal fines, and the workers wouldn't have to
> walk as far.
> 
> 5: The means of transport of charcoal fines would probably be by
> baskets carried on the heads of the labor force. It is relatively
> easy to carry such a load over level ground. It would be easier to
> walk a bit further on the level rather than walking uphill.
> 
> 6: The presence of terra cotta or pottery shards is incidental to
> Terra Preta, and not essential or even necessary.
> 
> 7: Charcoal retorts were made from clay, and were fired to pottery
> with the off-gasses from the retorting operation. Sometimes, when a
> retort was fired too quickly, it would break, and the partially fired
> retorts would be discarded.
> 
> Can anyone find errors in the above hypothesis? Can anyone add to it?
> 
> 
> Best wishes,
> 
> Kevin
> 
> Michael Bailes wrote:
>> Yes you are right. Logically,you would think if they went to the
>> trouble of grinding up charcoal they would do the same for pottery.
>>  So what is the answer? Shards would have to be fired to some
>> extent surely? Pottery made just for TP ? I don't know but would
>> love to find out. I doubt that firing temps would be much higher
>> than that needed for Terracotta. But I don't know. There may be a
>> bit on this In Amazonian Dark Earths if you can steal a copy
>> 
>> Here are a few posts I made on Hypography parent thread I don't
>> know if they get us anywhere. mb
>> 
>> This is from a research article translated from Portuguese a bit
>> hard to follow 
>> http://www.scielo.br/scielo.php?pid=...pt=sci_arttext<http://www.scielo.br/scielo.php?pid=S0044-59672004000200004&script=sci_arttext<http://www.scielo.br/scielo.php?pid=...pt=sci_arttext<http://www.scielo.br/scielo.php?pid=S0044-59672004000200004&script=sci_arttext>>
>> 
>> 
>> 
>> Quote: most of mineral grains were taken from fresh crystalline
>> rocks and intentionally crushed and introduced into clay material
>> as well as cauixi and cariapé.
>> 
>> The above described minerals and organic substances led to identify
>> the following materials as raw materials for the ceramics:
>> 
>> 1) clay material derived from weathering (saprolite/mottling zone)
>> of fine crystalline and less frequent sedimentary rocks (indicated
>> by clay-derived minerals and iron oxy-hydroxides, anatase and
>> quartz );
>> 
>> 2) fresh crystalline rocks crushed (feldspars, quartz and rock
>> fragments);
>> 
>> 3) organic materials (cauixi and burned cariapé).
>> 
>> 
>> The abundance of fresh feldspars, rocks fragments and roundless
>> quartz indicate that coarse igneous rocks, e.g. granites,
>> granodiorites, and even rhyolites and quartz of veins were used as
>> temper, after crushing. It's possible that pre-historic Indians
>> extracted the fresh rocks from the same place where they took the
>> clayey saprolite.
>> 
>> To improve the plasticity of the raw material they introduce
>> organic material like cauixi and cariapé, crushed quartz, or even
>> old ceramic (waste) crushed, in an old process of recycling. 
>> .http://www.scielo.br/scielo.php?scri...72004000200004<http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672004000200004<http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0044-59672004000200004>>
>> 
>> 
>> ABSTRACT
>> 
>> Several archaeological black earth (ABE) sites occur in the Amazon
>> region. They contain fragments of ceramic artifacts, which are very
>> important for the archaeological purpose. In order to improve the
>> archaeological study in the region we carried out a detailed
>> mineralogical and chemical study of the fragments of ceramic 
>> artifacts found in the two ABE sites of Cachoeira-Porteira, in the
>> Lower Amazon Region. Their ceramics comprise the following tempers:
>> cauixi, cariapé, sand, sand +feldspars, crushed ceramic and so on
>> and are composed of quartz, clay equivalent material (mainly burned
>> kaolinite), feldspars, hematite, goethite, maghemite, phosphates,
>> anatase, and minerals of Mn and Ba. Cauixi and cariapé, siliceous
>> organic compounds, were found too. The mineralogical composition
>> and the morphology of their grains indicate a saprolite (clayey
>> material rich on quartz) derived from fine-grained felsic igneous
>> rocks or sedimentary rocks as source material for ceramic 
>> artifacts, where silica-rich components such cauixi, cariapé and/or
>> sand (feldspar and rock fragments) were intentionally added to
>> them. The high content of (Al,Fe)-phosphates, amorphous to low
>> crystalline, must be product of the contact between the clayey
>> matrix of pottery wall and the hot aqueous solution formed during
>> the daily cooking of animal foods (main source of phosphor). The
>> phosphate crystallization took place during the discharge of the 
>> potteries put together with waste of organic material from animal
>> and vegetal origin, and leaving to the formation of the ABE-soil
>> profile.
>> 
>> I was wandering arround the Permaculture forums and came accross
>> this post which is interesting. You should vist the site if you are
>> into useful plants and gardening. It's great SEE: 
>> http://forums.permaculture.org.au/vi...?p=18201#18201<http://forums.permaculture.org.au/viewtopic.php?p=18201#18201<http://forums.permaculture.org.au/vi...?p=18201#18201<http://forums.permaculture.org.au/viewtopic.php?p=18201#18201>>
>> 
>> 
>> 
>> Re: Terra Preta What is the fuction of the clay pottery shards?
>> 
>> "PostPosted: Wed May 03, 2006 11:26 pm On reading about the actual
>> terra preta mix and process there are a lot of questions about the
>> presence of clay shards. I havent even read any speculation as to
>> why they are there. Two, things spring to mind.
>> 
>> Firstly, the ancients may have been carting this soil to other
>> areas or water to that site but woven baskets would have been more
>> feasible for the soil.
>> 
>> Secondly and more likely, possibly part of the reason for the
>> burning was that this was the place that clay was fired. Once a pot
>> was broken they could have been smashed over time or used as 'heat
>> beads' in the next firing. The refined pottery we use is fired at
>> incredible temperatures, this may not have been known to these
>> people and their climate was not condusive to sun drying [which can
>> take months].
>> 
>> Just idle speculation I doubt the ancients would have deliberately
>> tried build soils but they may have been building pots and stumbled
>> across a symbiosis in their process which lead to the terra preta.
>> 
>> I would love more speculation or clarification if anyone has
>> tracked down why the clay shards appear through this mix. The show
>> I saw on terra preta didnt mention them, only found it in further
>> reading.
>> 
>> Cheers
>> 
>> Floot mb
>> 
>> On 10/05/07, Allan Balliett
>> <aballiett at frontiernet.net<mailto:aballiett at frontiernet.net>>
>> wrote:
>>> 
>>>> I think clays are acid while charcoal tends to be alkaline so
>>>> there may be a clue thery to why it was used in TP. Like
>>>> charcoal it also has adsorption properties. If anyone could
>>>> point me to reach aricles wher it was used as asoil amendment i
>>>> would apreciate it
>>> 
>>> Michael - I've received contradictory information on whether or
>>> not the shards in Terra preta had been fired or not. I understood
>>> Charles C. Mann to say that they were not fired and the many of
>>> the shards were not from pottery but apparently made in sheets
>>> for terra preta use (only). From other sources, including general
>>> archeologists I hear that 'all pottery is, by definition fired"
>>> 
>>> My 'point' here is sort of: if the makers of terra preta wanted
>>> to incorporate clay for clays sake and they were already
>>> pulverizing char to 1x1mm, wouldn't they as well pulverize clay
>>> (or add in in a natural state) rather than include it in large
>>> pieces? Large pieces, which, the vary 'largeness' of could have a
>>> function outside of chemistry or nutrition?
>>> 
>>> -Allan
>>> 
>> 
>> 
>> 
>> 
>> ------------------------------------------------------------------------
>> 
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