[Terrapreta] The Science of Terra Preta Formation Re: Terrapreta Digest, Vol 15, Issue 14

[Kevin Chisholm]

Dear Sean

The key question was:
"In your opinion, are pottery shards a necessary component in "Old Terra 
Preta"?

I would suggest that they ARE a necessary component of "Old Terra 
Preta", as we commonly talk about on the Terra Preta List. I use the 
term "Old Terra Preta" in the sense of "Terra Preta Los Indios."

This is an Anthrosol. A key component in proving that "Terra Preta los 
Indios" was a man made soil is the presence of relevant artifacts made 
by man, of which pottery shards are the most notable.

I would pose that there are two kinds of "Terra Preta"....
1: that which is made by Man (Anthrosols, including Terra Preta los Indios
2: that which is naturally occuring

I would further pose that ONLY Black Earths that have the presence of 
relevant artifacts are Anthropogenic in origin. Clearly, any "Black 
earth" that had contained relevant artifacts made by Indians would be a 
"Terra Preta los Indios."

I would suggest that an artifact such as a gold necklace, widely 
scattered stone tools, or funerary items are not relevant evidence to 
support a "Terra Preta los Indios" label.

The presence of charcoal that is not present in a pattern more akin to a 
natural fire pattern would certainly constitute evidence of the activity 
of man in working the soil.

I would pose that there are many deposits of "Black Earth" or "Terra 
Preta" around the World, but that only some are Anthrosols, and that 
fewer still of these deposits are "Terra Preta los Indios."

You also state:
"I'm not sure the Amazon population then could have shit enough into 
enough chamber pots, and then broken them, in shatters, to make all the 
pottery shards found in all of the Terra Preta found in South America.  
I suspect all of the broken fired pottery was used to hold all the soil 
from washing away."

While I would have phrased it differently, it is indeed puzzling how 
they could make such a large area of Terra Preta. I would pose that some 
of the Terra Preta was naturally formed Black Earth, and that only some 
smaller fraction of it was of an anthropogenic nature. Given that 
pottery shards are rather durable, they could indeed have provided an 
erosion benefit. I would doubt that they would be added for the sole 
purpose of holding the soil from washing away, except possibly along the 
edges of water courses or irrigation channels.

Best wishes,

Kevin


Sean K. Barry wrote:
> Hi Kevin,
>  
> Lately, I've been thinking that pottery shards in Terra Preta soils 
> served mostly a mechanical purpose.  I think they were used to both 
> drain the soil and prevent run off of nutrients.  The inclusion of 
> pottery shards with charcoal in "Old Terra Preta" sites was either 
> done as a soil amendment, to do something there with that soil, or 
> maybe it was a coincidental, extraordinarily large pottery dump and 
> they just repeated it (thinking it was part of the TP effect observed 
> in that soil).
>  
> The scope of the projects (an area the size of France) suggests to me 
> that it was really sort of an industrial soil remediation, involving 
> large numbers of the population to manage the soils and the land.  
> There is evidence of elevated roads (which also you do not want to 
> wash away) in Amazonia as well.  Fired pottery was likely some of the 
> hardest, most water erosion resistant substances around.  Draining 
> water or maintaining an elevated mound within an annual inundation 
> would be easier in clay mud with lots of pottery shards around.  You 
> might even be able to make a pile of them in a flowing river and build 
> a bridge across that river.
>  
> Initial development of the idea that the mixture of wastes and 
> charcoal made for better plant growth may have been inspired by 
> observation of plant growth over old dump sites.  This seems 
> plausible.  Maybe they just copied what they observed and pottery was 
> incidental to the dump sites, so they put it in when they tried to 
> build TP sites.  It seems that they then tried to repeat this TP 
> phenomenon on a larger scale.  No TP site is naturally occurring?  All 
> Terra Preta sites are synthetic?
>  
> I'm not sure the Amazon population then could have shit enough into 
> enough chamber pots, and then broken them, in shatters, to make all 
> the pottery shards found in all of the Terra Preta found in South 
> America.  I suspect all of the broken fired pottery was used to hold 
> all the soil from washing away.
>  
> Regards,
>  
> SKB
>  
>  
>
>     ----- Original Message -----
>     *From:* Kevin Chisholm <mailto:kchisholm at ca.inter.net>
>     *To:* Sean K. Barry <mailto:sean.barry at juno.com>
>     *Cc:* terrapreta at bioenergylists.org
>     <mailto:terrapreta at bioenergylists.org> ; Greg and April
>     <mailto:gregandapril at earthlink.net>
>     *Sent:* Monday, April 07, 2008 12:22 PM
>     *Subject:* Re: [Terrapreta] Terrapreta Digest, Vol 15, Issue 14
>
>     Dear Sean
>
>     In your opinion, are pottery shards a necessary component in "Old
>     Terra
>     Preta"?
>
>     Kevin
>
>     Sean K. Barry wrote:
>     > Hi Greg,
>     > 
>     > I think that it is only where charcoal-in-soil was put.  If it
>     > spreads, why hasn't it in 4500 years?  How can we find individual
>     > sites now, closely spaced?
>     > 
>     > Regards,
>     > 
>     > SKB
>     >
>     >     ----- Original Message -----
>     >     *From:* Greg and April <mailto:gregandapril at earthlink.net>
>     >     *To:* terrapreta at bioenergylists.org
>     <mailto:terrapreta at bioenergylists.org>
>     >     <mailto:terrapreta at bioenergylists.org>
>     >     *Sent:* Monday, April 07, 2008 11:22 AM
>     >     *Subject:* Re: [Terrapreta] Terrapreta Digest, Vol 15, Issue 14
>     >
>     >     I think we do need to understand the origins of Terra Preta - at
>     >     least in part to understand the mechanics of how it has
>     >     become self sustaining, and wither or not the science behind it
>     >     would be useful in other places.
>     >     
>     >     What clues can we find?    Other than pottery shards and the
>     >     physical / structural makeup of the char,  there is not much
>     else
>     >     that I know of due to the nature of the area.
>     >     
>     >     You are correct, that studying the nature of the mined TP might
>     >     give a few more clues.
>     >     
>     >     
>     >     Why is it self sustaining?    Personally I think that it's a
>     >     matter of achieving a given nutrient density and CEC level after
>     >     which the density of the plant life is able to keep it going.  
>     >     
>     >     What I would like to know is it able to spread or is it just
>     >     confined to the areas of human influence.
>     >     
>     >     
>     >     Greg H.
>     >     
>     >
>
>
>