[compost_tea] calcium sulfate (gypsum) questions

From: George and Paulette Mouchet <geomouchet_at_QNET.COM>
Date: Mon, 8 Sep 2003 14:23:41 -0700

Dr. E previously mentioned that gypsum should be applied at less than 100
pounds per acre per application.

Is the application yearly, monthly, once?

I did some calculations. 100# per acre = 0.04 oz per square foot.
1 tablespoon of Whitney Farms Prilled Gypsum weighs 0.6 oz, which is still
15X Dr. E's recommended application level.

The Whitney Farms box suggests applying 1/2# per rose bush 1-2 times/year.
 (If you allow 16 square feet per rose bush, this is about 1 tablespoon per
rose bush.)

Dr. E said adding gypsum causes osmotic shock to the soil critters and
kills them (I'm assuming this happens at levels higher than 100# per acre).
 So, why use gypsum in the first place? Is applying >100# per acre going
to add enough Ca to the soil and/or improve aggregation enough to make it
worthwhile? Is there a better way to add Ca to the soil?

Dr. E also said that gypsum improves soil aggregation but only on the short
term. Then the soil becomes hard again.

I'd like to understand what/how/why this happens.

I know the Ca supplied by the gypsum is used to make the glue that forms
soil aggregates. Does the glue break down after awhile causing the
aggregates to fall apart?

What happens to the Ca from the glue (that originally came from the
gypsum)? And, what causes the glue to break down?

What happens when gypsum is added to soils high in sodium? I know the Ca
in gypsum is released and supposedly replaced by Na. What are the chemical
products of this reaction? What happens to the new sodium molecule in the
soil?

Jose Garcia said previously that adding gypsum ultimately robs the soil of
Ca (unless there's more than 60% base saturation of Ca to start with). He
states that the Ca and other anions (H, Na, K, Mg) "leave" the soil. Where
to they go? Are they leached out? What if you have a heavy clay soil that
doesn't leach well? And/or water high in soluble salts. Wouldn't these
anions simply hang around causing increased salt problems in the soil?

Many thanks,
Paulette







        

-----Original Message-----
From: soilfoodweb_at_aol.com [SMTP:soilfoodweb_at_aol.com]
Sent: Monday, June 02, 2003 12:20 PM
To: compost_tea_at_yahoogroups.com
Subject: calcium sulfate, corn gluten

Gypsum can give you salt impacts - that is, osmotic shock. Too much of
anything is a problem. So, keep the application down to less than 100
pounds per
acre, and no problem. More than that, and in general, we see problems.

Typically, gypsum helps improve flocculation for a short time, and then the
soil turns into bricks because the biology was lost.

Hard soil surfaces suggest a lack of the appropriate biology, a lack of
food
(organic matter) to keep the organisms active, or an impact in the past
that
wiped out the biology, or a disturbance that compacted the soil. I don't
care
what soil health you have, you can compact anything given a big enough
machine, a large enough volume of salt, or a period of negligence in a high
traffic
area (which is my lawn). Rain can compact soil where the biology is too
low.

I got my yard to a place where I had good soil tilth, and then proceeded to
ignore my yard for about 8 years. I have thatch developing, the moss is
out of
control in the back and side yard, and the soil is now HARD. Darn. I have
lost my fungi. I forgot to feed my critters for the last few years. They
are
letting me know. Still have good grass, but lots of thistle, composites,
and
the grass is encroaching on my trees, and perennial areas. All signs that
my
fungi are not happy.

Why did my fungi disappear? The neighborhood association hired someone who
came around two years ago and sprayed something that killed everything -
grass,
weeds, rose bushes, donkey's ear, clover, etc in a swath all along the back
side of my property. Impressive. And the soil is cement there.

Was that the only insult that has put my land over the edge? Probably not,
too many kids playing soccer on my lawn, total clay substrate, and lack of
diversity of fungal foods probably helped. I have forgotten the compost
for many
years now.

So, how to fix? Compost tea alone has not been enough. Probably have
herbicide residues in there that are just out of sight. Probably lacking
calcium.
I use eggshells to help the calcium situation, and that's helping (at least
the dandelions are no longer growing faster than the grass). How much
gypsum
would be beneficial? Keep it under 100 pounds per ac per application.....

So, I have to get some compost, keep spraying tea, and get that calcium out
there. I'll put calcium in the compost (calcium carbonate, or calcuim
hydroxide or oyster shell), in the tea, and as eggshells direct to the
lawn. And corn
gluten in the spring to tie up excess nitrate.

Hope this helps.

Elaine Ingham
President, Soil Foodweb Inc.
www.soilfoodweb.com
SFI Oregon, USA
SFI Australia
SFI New York
SFI Europe
SFI New Zealand

"Hope is not a feeling. It is not the belief that things will turn out
well,
but the conviction that what we are doing makes sense, no matter how things
turn out." -- Vaclav Havel, former President of the Czech Republic

 << File: ATT00026.htm >>

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Received on Mon Sep 08 2003 - 22:02:46 EDT

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