Clay Soil and Gypsum

Adam Fikso
Sat, 23 Jan 2010 22:39:28 PST

For my yard, I mix pelletized gypsum into the soil at a rate of about  3 to 
5 by volume. I have a sticky clayey loam (prehistoric shore of Lake 
Michigan) silty with rocks sometimes. Without gypsum the soil cannot be dug 
in summer because it gets rock hard.  With water, it's workable. It also 
needs lots of coarse organic stuff in it, wood chips, and grits, coarse 
builder's sand to maintain any kind of friability.

The people who think that gypsum doesn't help-- some of them-- decided that 
they were going to use plaster of paris ,i.e.,calcium sulphate which has the 
same formula except for the water content--6 or 7 molecules per sulphate 
molecule as I recall. (check it yourself ).  Doing that will guarantee that 
your soil will set hard as a rock due to the crystallization into gypsum. 
Plaster of Paris IS gypsum that's been heated to drive the water molecules 
out.  The minute it gets wet, it sets.  However, when gypsum (plaster) is 
broken up into dust, (crystals) they penetrate the soil and move around in 
it coating various bits on the molecular level, keeping it friable. Old 
plaster walls can be useful too when broken up, crushed and spread around.

These are issues of fact not opinion. Check them out in a high schol 
chemistry book or on lne.

----- Original Message ----- 
From: <>
To: <>
Sent: Saturday, January 23, 2010 4:39 PM
Subject: [pbs] Clay Soil and Gypsum

> Of those of you with clay soil, do you really feel that adding gypsum
> helped your clay?
> If so, how much did gypsum did it take to produce a difference?
> (I'm asking this because I've seen several references to gypsum NOT
> working as well as gypsum producing miracles.)
> Thanks,
> Anita Clyburn
> Surrounded by an ocean of cold wet clay mud in Terre Haute, Indiana.
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> pbs mailing list

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