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["Lynda" <lurine AT com-pair.net>]

O.K., I can slog my way through Spanish with great effort.  So, I'll 
question you instead. <g>

What type locations are the Terra Preta in in S.A.?  The "black valley" as 
it was known to the indigenous people in Rohnert Park is in a basin that was 
surrounded by creeks and flooded every spring.  The area was "farmed" by the 
Miwok for thousands of years and was routinely burned (a CA Indian tradition 
to keep meadows and farm land free of the wrong trees. [black oak come back 
from fire and were preferred for acorns] I'm no expert on other areas, so 
can only speak of CA).

Now, since they can't go in and tell much about Rohnert Park anymore, I 
wonder if it would have been the same/similar to what is in SA.  And since 
we're talking basins in both instances, I wonder how much flooding would 
have to do with it.  The flooding in a basin would be quite different than 
the silt dropping of the type flooding that the Mississippi does.

Lynda

----- Original Message ----- 
From: <Clansgian AT wmconnect.com>

> >In the Amazon basin, when they dig some of the Terra Preta up, as long as
> they only take a little at a time and leave enough in the patch, it seems 
> to
> "grow back"...

Terra Preta was a hot topic on another forum a while back and we all did a
bit of reading about it.  I found that literature from the US was very 
heavily
tainted by agribusiness thinking, forever coming back the notion that we 
could
somehow mine the Dark Earth or at least put something in a bag  that could 
be
sold and scattered on our gardens.

But the Brazilian literature was different, more analytical, more examining
what the phenomenon is rather than how we can sell it.

In the Brazilian literature it is called "Terra Preta do Indio"  (Indian 
Dark
Earth). This is one of the most informative articles on the subject (says 
I):

http://www.museu-goeldi.br/destaqueamazonia/tpa.htm

Under the section "hipoteses" the first sentence begins:

"Pesquisadores estimam que um centímetro de terra preta leve pelo menos 10
anos para se formar"

(Analysists estimate that a centimeter of dark earth takes at least 10 years
to form.)

Yowser, guys!  A millimeter a year!?  Sorry, but I'm already doing much
better than that by my own humble composting.

As to the charcoal being the key, there are also areas of "terra mulata"
(brown earth) which have the same characteristics of fertility longevity as 
the
terra preta but lacking the charcoal of the latter.   Like the terra preta 
the
terra mulata sites are identified as areas of long habitation and 
cultivation.

The places where these phenomena occur are laterite soils.  The game plan of
these soils is very different from temperate soils.  Here organic matter 
lies
in the ground decaying and harboring the bulk of the fertility.  There,
because the bacteria can work around the calendar, organic material does not 
abide
long in the soil.  The scheme is for plants to take up all the nutrients and
hold them with the soil being more or less sterile.   That's why when rain
forests are cleared for agribusiness agriculture, it permanently harms if 
not ruins
the ground.  All the nutrients of thousands of years are removed in a day
when the overlying vegetation is removed.

So compared to the laterite soils, the terra preta and terra mulata are very
persistently fertile indeed.  Why?  Dunno.  And apparently neither does 
anyone
else.  But the notion that what's going on down there in that type of soil
can be successfully duplicated here in a very different climate and very
different soils has yet to be demonstrated ..... except to demonstrate the 
general
concept that accumulated organic material makes the soil more fertile seems 
to
be a universal principle.

This same thing comes into play, I think,  in John Jeavon's double digging.
He showed dramatic improvement in yield by double digging compared to 
shallow
tilling .... in Palo Alto, California.  What's the soil and climate like? 
Not
the same as here, and that's the main thing.  Double digging just doesn't
give the same results for the labor everywhere.

James
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