[Terrapreta] The Science of Terra Preta Formation

[Sean K. Barry]

Hi Jim,

I think you are right about clays.  They are mostly aluminum silicates with some iron and feldspars and stuff, but not a lot of C HOPKINS CaFé Mgr plant nutrients in them.  They also do not impart that great of CEC, especially when added on top of existing clays.  I think the chemical role of the shards would be very limited, too.

I liked what Lou just mentioned about thinking about the shards as there for possibly a different reason.  Does fired pottery (like terra cotta) hold water better than clay mud?  Maybe pottery was a sponge?  Does it prevent run-off, unlike what the soil can do.  Maybe there is something in the shape of the sites which would point to a different use?

Regards,

SKB
  ----- Original Message ----- 
  From: Jim Joyner<mailto:jimstoy at dtccom.net> 
  To: Terra Preta<mailto:terrapreta at bioenergylists.org> 
  Sent: Sunday, April 06, 2008 5:06 PM
  Subject: Re: [Terrapreta] The Science of Terra Preta Formation


  Sean K. Barry wrote:  
  > Clay pottery made from clay on the mountains!?  Maybe this could be 
  > found out, the origins and makeup of the pottery shards?  If it shows 
  > raw materials from multiple sources, then this could support a 
  > hypothesis that the Pre-Columbian people were trying to concentrate 
  > nutrients onto a site and with the addition of charcoal trying hold 
  > them onto that site.  Already we know they added nutrients in the form 
  > of fish bones (obviously not originally from the soil).  They may have 
  > realized that the combination of charcoal and nutrients leaves 
  > fertility that does not wash away.  A cooking fire in the rain that 
  > was left turned out to be a fountain of plant growth later.
  Seam,

  Hmmm . . . interesting idea. I still have a hard time believing the 
  shards themselves have much effect on the soil. But you may be 
  indicating an altogether unconsidered source(s) of nutrient -- and 
  concentrating scheme. That doesn't sound far fetched but it would take 
  such huge quantities if we are talking about clay. It is hard to 
  understand how they might have done it. I mean, they didn't have trucks, 
  not even horses (lamas?). It is possible that they had a lot of human 
  beings for such transport but even that seems uneconomical: to have all 
  your people walking to the mountains (or where ever) with baskets. It 
  would take a lot more calories than could be returned if the distance 
  traveled was lengthy at all. Still, an interesting idea.

  Jim

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