[Terrapreta] Early Terra Preta Production

[Robert Klein]

I totally agree, but they can be associated with the time of manufacture and can powerfully indicate the principal crops.  Their actual presence is actually anomalous for the region in any event, or at least corn is.

What I have been able to extract to date is the pollen evidence for corn and cassava culture.  And yes large chunks of wood charcoal should retain cellular information that can support identification.  The problem we have with effectively powdered soft plant charcoal is that it may not be that easy and could have been easily overlooked.

I would have screened the material and picked  out the nice shiny chunks reasonably assuming this was representative of the fine powder and been totally misled.  This is however a question that may be answered by a specialist in this type of identification who is forewarned.  Do we have samples to hand and a specialist?  Most identification of this type is focused on wood identification.

Actually, my kids have access to the UBC forestry faculty who would be able to do this type of work.  They may even be able to char some corn stover in an oven to compare while we are at it.

does someone have good samples of terra preta?.

----- Original Message ----
From: Gerald Van Koeverden <vnkvrdn at yahoo.ca>
To: Robert Klein <arclein at yahoo.com>
Sent: Tuesday, January 8, 2008 2:41:43 PM
Subject: Re: [Terrapreta] Early Terra Preta Production



Pollen evidence only tells us what plants grew in the area, not what the charcoal was made from.  As you can see by the quote from a study below, scientists have the means of identifying both the age and species of the source origin of charcoal buried in the soil.  Its called "soil forensics."  Certainly, it must have already been done for terra pretas??

"The charcoal collections were carried out in the main massifs of present-day rainforest between latitudes 15-degrees-30'S and 19-degrees-15'S and longitudes 145-degrees-E and 146-degrees-30'E. All charcoal was collected from locations which precluded the possibility that the charcoal had been transported. Much of the charcoal retained cellular structure, and the taxonomic source was determined using an electron scanning microscope and wood identification keys. All positive identifications belonged to the genus Eucalyptus. Radiocarbon dated samples revealed ages between approximately 27,000 BP and 3500 BP with the majority of samples in the period 13,000-8000 BP."


http://www.citeulike.org/group/342/article/1306925


Gerrit

On 8-Jan-08, at 4:03 PM, Robert Klein wrote:

Hi All








Early Terra Preta Production
















      As
my long time blog readers know, terra preta is a man made soil located
in the Amazon by the Indians up to the time of the conquest for at
least a thousand years. Besides the substantial 15% content of powdered
charcoal we have an additional persuasive content of apparent broken
pottery shards throughout.


The Indians were able to produce
powdered charcoal while consuming a lot of low grade pottery in the
process. This is many tons of charcoal per acre. The manufactured soil
retains fertility without significant assistance in an environment were
its only competitor is low productivity slash and burn. High density
settlement resulted and was almost certainly responsible for the
legends of El Dorado. The Spaniards were about a generation too late
and the knowledge was lost.]


Reconstructing the production protocol was tricky but is is really very simple. 


It
was and still is impossible to use wood economically to produce the
powdered charcoal. I say impossible because the direct costs of
harvesting wood is well known and the cost of producing charcoal is
also well known. That implies that wood charcoal which also has to be
fine ground must have a cost base approaching that of sawn wood. The
sunk cost is far too high to ever use as a soil additive. This is borne
out even in Africa were we see charcoal been made to take advantage of
its direct cash value as fuel.


That leaves us with dry crop
residue as a source material and a very productive one to boot. In the
time and place, and this is almost still true today, the only crop that
fitted the volume need to make the process practical is and was corn.
Today bagasse could also be used. The important factor is tonnage per
acre. Corn is good for ten tons per acre. Most other crops simply fail
to produce enough plant material. Additionally, corn waste or stover
must be removed and burned regardless.


Since it must be gathered
and burned in any event, the question is how to convert this feedstock
into a ton or two of powdered charcoal or more reasonably into biochar
retaining both the charcoal content and some remaining plant material.


Here,
the nature of the corn root itself helps out hugely. It form a flat
disc, not unlike the base of a floor lamp. This dirt ball can be
treated almost like a brick. It permits the building of tightly packed
stacks whose outer wall is formed be tightly packed root discs loaded
with mud. It is no big trick to build a vertical wall of these root
discs to act as the outer shell of what is a temporary earthen kiln. It
was actually a brilliant innovation by some Indian a couple of
thousands of years ago.


This earthen kiln is then fired by the
process of dumping a charge of glowing wood coals on the top of the
stack, directly into the packed dry corn stalks, and covering it
immediately with the sun dried earthen platter that carried the coals.
You would then cover the top with additional dirt to maintain the
integrity of the earthen kiln and let the coals do their work.


The coals will drive a chimney
into the stack and all the combustion will take place inside the
covered chimney. This nicely minimizes any unnecessary energy loss and
maximizes combustion which goes into reducing the balance of the
stover. The earthen wall even filters out any errant heavy gases as
they try to escape. I suspect that it is only with the recycled gas
systems of today that we can do better.


This task would be done
after the corn had fully ripened and dehydrated which occurs just after
harvest. The corn stalks dry out then and are still pretty impervious
to wetting by rain.


Once the burn is complete the next day, one
would rake out any unburned roots to throw into the next kiln and then
take baskets of the soil - charcoal mixture back into the field to
produce the hills for the next crop. The only tool used would be the
earthen ware pottery and a strong back. Today I would use a metal garbage can lid.


This
process produces enough material to salvage the field in tropical
conditions for an immediate crop during the next season. Once this was
understood, it became practice and was intensively employed long past
its actual necessity for many thousands of acres in the Amazon.


When
I first made this hypothesis on the likely protocol, I did a literature
search of the Archeological data on the Terra Preta soils looking for
the pollen data. Remember that corn is not your first choice of a crop
plant on a rain forest soil. I was gratified to discover that the two
principal crops were corn and cassava which also produces a lot of
biomass but no usable root ball. This confirmed that the protocol had
legs.


I am quite prepared to work with someone who wishes to run
field tests at no charge since I personally think that this will
revolutionize all subsistence farming generally as they can be the
first adopters. Larger acreages will need kiln equipment at the least
and this will be capital intensive.


And it would be great to get
this going where the crop cycle is currently multiple years through
slash and burn. I think particularly of the Philippines were I have had
fifteen year fallow periods reported. The same must be true for a lot
of land in Africa and elsewhere. The more interesting question is the
fertility increases in soils now been exploited.




Arclein


http://globalwarming-arclein.blogspot.com






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