[Terrapreta] Early Terra Preta Production
Robert Klein
arclein at yahoo.com
Wed Jan 9 12:43:43 CST 2008
Hi Sean
No one said it did except perhaps to act as a proxy for wood anywhere and I saw no need to say even that.
Agricultural residue is normally from annuals like corn and they are usually not woody, thus making their handling easy. In fact corn and bagasse likely represent some of the harder to work with annual residue which is why they are such a problem. Wood waste needs to to be carefully cut in order to achieve a reasonable packing ratio. In the modern world we have chippers but even that will give a packing ration of only 50% or so which likely forces the use of air tight containment to achieve efficiency.
Traditional charcoal makers built open air kilns by using split blocks of uniform thickness, tightly packed, increasing the packing ratio to plus 70%. I do not know how they prevented burn out, although mud on top would help. Perhaps they put green wood on the outside.
regards
bob
----- Original Message ----
From: Sean K. Barry <sean.barry at juno.com>
To: Gerald Van Koeverden <vnkvrdn at yahoo.ca>; Robert Klein <arclein at yahoo.com>
Cc: terra pretta group <terrapreta at bioenergylists.org>
Sent: Tuesday, January 8, 2008 9:15:04 PM
Subject: Re: [Terrapreta] Early Terra Preta Production
DIV {
MARGIN:0px;}
Hi Robert,
What does Eucalyptus charcoal in Queensland, Australia have to do with the
charcoal feedstock source in the Amazon rainforest?
Regards,
SKB
----- Original Message -----
From: Robert Klein
To: Gerald Van Koeverden
Cc: terra pretta group
Sent: Tuesday, January 08, 2008 5:00
PM
Subject: Re: [Terrapreta] Early Terra
Preta Production
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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