[Terrapreta] Earthen Kilns Conjecture

[Robert Klein]

These are good thoughts.  I just do not see the volume to compare with the fifteen percent content of a terra preta soil.  Usually black earth that I have seen is indicative of a hearth of some sort were fines would accumulate or be produced.

Certainly a field burn of corn or cassava waste could produce a large scorched patch of soil with some charcoaled organic matter.  However I have done exactly that with very dry hot burning brush.  The folks came from miles to check out the barn burning.  The air flow feeding the fire kept the soil cool enough to work with and walk on immediately.  And everything was turned to ash without any black soil.  The same must hold true for corn stover.

bob

----- Original Message ----
From: Greg and April <gregandapril at earthlink.net>
To: Robert Klein <arclein at yahoo.com>
Cc: terra pretta group <terrapreta at bioenergylists.org>
Sent: Thursday, April 17, 2008 5:14:19 PM
Subject: Re: [Terrapreta] Earthen Kilns Conjecture

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  ----- Original Message ----- 
  From:   Robert Klein   
  To: Greg and April 
  Cc: terra pretta group 
  Sent: Wednesday, April 16, 2008   23:53
  Subject: Re: [Terrapreta] Earthen Kilns   Conjecture
  SNIP
  
The charcoal volumes are too 
  low to for this to hold.  The only reason they wold ever make chacoal as 
  a separate product is as a convenient fuel, and even then it would likely be 
  used for firing pottery.

Why only for 
  pottery?
   
  Indiginious people's on most contentents used 
  charcoal for fuel.
   
  Follow my line of reasioning for a bit.
   
  1)    We have historical accounts of 
  miles of rivers where homes were packed right next to each other, with large 
  cities in the background.    That's not alot of room to supply 
  alot of fuel wood.
   
  2)    Wood rots real fast in the 
  tropics, charcoal does not.
   
  3)    Wood for fuel is heavy for the 
  energy it produces, while charcoal is lighter and has more BTU's than wood 
  does.
   
   
  What if like in other countries ( even today ), they 
  produced large volumes of charcoal on the outskirts of the cities, for sale 
  and distribution within the cities?    
   
  A single person can easily carry a weeks worth of 
  fuel for cooking the meal for a family in a couple of baskets or 
  even a conue of any real size.    It will not rot, or have 
  other issues with the water while waiting to be used.
   
  See what I'm thinking of?
   
        If this is the case, then the smalls and 
  fines would be everywhere.
   
   
  One last thing on the charcoal for fuel 
  thought.    There are some species of wood in South America, 
  that are known to the natives and being good to make into charcoal - just how 
  long they have known that is up to debate, but they do have the knowlage of 
  them.
  
SNIP
  
> 

  The problem with the   theory of earthen kilns, is that such earthen kilns would also fire   them selves into a ceramic - yet no indication of such a structure has   been found.    There is a man that builds ceramic structures,   by building structures out of adobe bricks, then fires the entire building,   making a monolithic ceramic structure.

This is an important question.  
  Biochar temperatures are running at around 300 to 400 degrees for most of the 
  stack.  high temperatures would only exist within the chimney were the 
  earthen ware cap would also exist.  An important question is to determine 
  the firing temperature of the so called pottery in the 
  soils.





  Yes and No.
  There are two things that govern ceramic 
  hardness, tempature and time, and an increase in either one can to a degree 
  make up for the other.    In fact there is one style that I 
  heard of but can't name off hand, it actualy goes through several low 
  tempature firings, but when done it's almost as hard as if it went through a 
  single firing at a higher tempature - and because it is fired at a low 
  tempature, it's less inclined to crack when in the kiln, if there was still 
  some moisture in it.
   
   
  Greg 
H.






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