[Terrapreta] The Science of Terra Preta Formation

[Greg and April]

The sulfate ions, combines with the sodium ions, allowing the calcium ions to take their place in the soil.

This has two effects:

The first is to open up the soil, as sodium tends to cause soil collapse.

The second is it tends to then transport the sodium down stream with the irrigation water, until it either goes into the sea, or if it "dead ends", it causes soil collapse and build up of salts until it reaches toxic levels.

Greg H.

  ----- Original Message ----- 
  From: Sean K. Barry 
  To: Terra Preta ; Jim Joyner 
  Sent: Sunday, April 06, 2008 17:56
  Subject: Re: [Terrapreta] The Science of Terra Preta Formation


  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 
    To: Terra Preta 
    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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