[Terrapreta] Earthen kilns in Cyprus and dry laqnd use of biochar and ash

[Robert Klein]

Hi

I fully agree.  The one thing that I have not seen is a paper on the pottery shards themselves that identified firing temperature and even the source of the clay.  We can assume that these are local clays that would likely be totally unsuitable for actual pottery but we might be quite wrong.

I do know that I tend to propose a minimalist model and usually the evidence when it appears adds legitimate complexity.  My informant told me that they simply have a small hole in the top of the structure for escaping gases and a small hole on the side at the bottom to allow a small intake of air.  In the meantime air flow through the walls is cut off by the wet clay or mud.  This is a vastly more constrained air flow than I had ever imagined.

This informant has just saved us several poor test results.  Does anyone have any real data on the so called pottery shards?

arclein


----- Original Message ----
From: Philip Small <psmall2008 at landprofile.com>
To: Robert Klein <arclein at yahoo.com>; Terrapreta at bioenergylists.org
Sent: Wednesday, May 7, 2008 1:36:20 PM
Subject: Re: [Terrapreta] Earthen kilns in Cyprus and dry laqnd use of biochar and ash

I don't know if the pottery shards associated with TP are consistent with an earth covering or more formal shaping, but there should be a distinct difference in morphology. Those who have examined these shards would be in a position to confirm.  I can comment that the clay that forms in tropical soils are of a more refractory mineralogy than clay which forms in more temperate zones: the premise that a soil covered kiln could produce fire hardened shards is entirely plausible from that perspective. -phil



On Wed, May 7, 2008 at 12:07 PM, Robert Klein <arclein at yahoo.com> wrote:


I posted these helpful tidbits in my Blog today.  This is likely as close as we will ever get to interviewing the makers of terra preta.   There is growing evidence of Bronze age trade between the Mediterranean and the Amazon Basin.

arclein



Dry Land Biochar
I had a very revealing discussion with an
old acquaintance today that drifted into the possibilities of biochar
and proving that you never know who your informants might be. He grew
up in Cyprus and is of Turkish ethnicity. When I shared with him a
description of the earthen corn kiln method, he pointed out that the
making of charcoal for fuel is done traditionally by building a tight
packed heap of wood that is then covered by slapping wet mud over the
outside. A small hole is left in the bottom were a fire is started and
another small hole on the top creates the chimney.

Hearing this,
the only remaining question is how could they not form earthen kilns to
produce valuable biochar the exact same way? In the Amazon, the extra
step could well have been slapping wet clay on top of the outer shell
formed by the roots. It would take a little extra effort, yet even
better burn control could be achieved. Plenty of pottery like shards
would also be produced over the decades as has been discovered.

Obviously
the natives fully understood the value of the method if only because
this biochar product from corn stover served no purpose other than
somewhat convenient disposal and soil enhancement. However, the work
load change was trivial as the corn was been pulled in any event and
needed to be burnt. This was not a valid value proposition for wood
which is very costly to cut and pack and was done to provide a
valuable fuel.

I also learned something very important about dry land agriculture.
If you form a seed hill, normal planting usually provides erratic
results. If ash is added to the hill, or zeolite for that matter, moisture is drawn in during the night supporting vigorous growth. My informant was able to plant melons side by side with dramatic results.

This
informs us that the additional strength of biochar as a water attractor
is been underestimated. I would now like to see the three sisters
method applied in places in Africa were common sense suggests
otherwise. One could even begin seed hills with wood ash to get it all
going and then follow up each year with a dressing of biochar.

I also understand better the importance of squash to the three sisters system.  The broad leaves of the squash would shade the intervening soil between the seed hills keeping it cool and speeding up the absorption of moisture from the atmosphere were possible.

As I have posted in the past, activated carbon,
zeolite and ash form a class of substances that are called solid
crystalline acids. They are all strong absorbers of water and the free ions of nutrients.  This is why they create and sustain fertile soils.

I do not yet understand why the three sisters culture has not been adopted worldwide among subsistence farmers.  Most of it has to do with the advent of draft animals that enforce a row cultivation system and the three sisters simply do
not accommodate that. Most small plots are done with hand seeding
anyway, which again begs the question. It seems little to ask to stand
over a three foot seed hill and to plant a handful of corn and bean
seeds properly spaced with a couple of squash seeds every third hill.
In fact it would be fast and economical of effort.


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Philip Small, RPSS
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