[Terrapreta] Praire is natures way of making terra preta.

[David Yarrow]

the notion the midwest's thick dark loams are glacial deposits is as falacious as the original assumption terra preta was a natural geological deposit.  glaciers deposit minerals from cracked, scoured and pulverized rocks.  they didn't deposit (hardly) any organic materials.

the last continental glacier retreated 10-12,000 years ago.  with a fresh supply of primary, unreacted rock minerals and trace elements, biological nature rapidly turned inert dirt -- primary rock minerals -- into topsoil.

many prairie and forest plants send dense root structures six, eight, even ten feet into the ground.  some are taproot structures; others are fine mesh, highly branched networks.  when these plants die, they leave all their carbon skeletons deep in the soil.  and larger soil organism such as earthworms further distribute organic matter  throughout the subsoil.  10,000 years in highly mineral enriched soil is more than enough time for nature to create high carbon soils several feet deep.

but it only takes a century (or less) of plowing and chemicals to burn off most of that organic matter.  after all, the tractor was only widespread beginning the early 1900s, and ag chemical didn't widely proliferate until after WW2.

which is part of the intrigue and mystery of terra preta and charcoal: their fertility, organic carbon content and stucture hasn't degraded all that much in 300 years of intensive use.

David Yarrow
"If yer not forest, yer against us."
Turtle EyeLand Sanctuary
44 Gilligan Road, East Greenbush, NY 12061
dyarrow at nycap.rr.com
www.championtrees.org
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if one only remembers to turn on the light."  
-Albus Dumbledore
  ----- Original Message ----- 
  From: lou gold 
  To: Gerald Van Koeverden 
  Cc: Terrapreta at bioenergylists.org ; bhans at earthmimic.com 
  Sent: Saturday, September 01, 2007 10:41 AM
  Subject: Re: [Terrapreta] Praire is natures way of making terra preta.


  Hmmm. I grew up in Illinois and was taught that the deep rich black loam soils were "pushed" to their present locations as advancing glaciers scraped away the top-soils to the north. Is this an incorrect view?

  I think my wording was a bit inaccurate.  All soils grow through nature's processes.  My  point was simply that they did not grow to the great depths in the Midwest as they did and do in the Amazon. Soil that grew to the north was deposited along with native growth.
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