[Terrapreta] The Science of Terra Preta Formation

[Sean K. Barry]

Hi Jim,

I worked for just a short time on a vineyard in California, circa 1999.  The California Department of Agriculture people and the farm manager recommended gypsum applications right at the base of the vine rows, calcium sulfate dihydrate (CaSO4-2H2O), to improve water retention in the soil and improve the ability of the soil to deliver water to the vines.  I don't know how calcium improves the ability of soil to deliver water to plants, but that is what these people were trying to accomplish.

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 7:32 PM
  Subject: Re: [Terrapreta] The Science of Terra Preta Formation


  Greg, Sean,

  There's another peculiar characteristic of clay that can only be 
  addressed with calcium.

  Clay will hold lots of water. Unfortunately that water is not available 
  to plants unless . . . What makes clay friable and the water in it 
  available is calcium/magnesium. Without sufficient calcium  (60 to 70% 
  of the base saturation is considered ideal) clay will not grow much of 
  anything even if nutrients are in the clay. I can't speak about char but 
  the same applies to humus in the soils. There are places in Ohio and 
  Indiana where they have muck soils (extreme high levels of OM/humus) 
  that require huge amounts of calcium to unlock nutrients and moisture.

  I don't know, but I doubt that char changes these rules (ideal soil has 
  60-70% of base saturation is calcium; 12% magnesium; 2% potassium). If I 
  remember right, the Amazonian clays are acid which would indicate low in 
  potassium (Unlike bentonite that is very alkaline with lots of 
  potassium). Potassium is important but to much -- relative to calcium -- 
  makes soil into brick, seals pond bottoms.

  Jim



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