<p>Apparently building gypsum is also known as Plaster of Paris. I put a few tons of gypsum drywall on a 1200 sq.ft. garden.  It is free in some locations ( I got &quot;bearings&quot; - 6&quot; X 48&quot; strips- in a small railyard). I wanted to acidify my clay soil. Over winter the paper on each side, got wet and came off so I had to pick up and discard paper . In spring , I rototilled with a serious ( Howard Gem, 18 Hp Wisconsin) borrowed rototiller. So it was messy , some work, but free. An alternative is plaster of Paris power in a bag as you describe, very neat but costly in quantity. So you can add gypsum but what isthe objective, to add sulfur ? I was trying to change pH, that was relatively ineffective with gypsum.</p>

CC BY-SA 4.0
2022-03-04T21:02:39.450Z
I don't know as I am following a recipe, but I think that, yes, it is to add sulphape ions, as the dolomite lime will raise the pH. What I am askin, I guess, is if such gypsum contains other unwanted additives. And by the way, it is not plaster
aaa
CC BY-SA 4.0
2022-03-04T21:45:53.287Z
Gypsum is calcium sulfate , should be no additives unless marked as such.
blacksmith37
CC BY-SA 4.0
2022-03-04T20:42:16.100Z
2022-03-04T21:47:45.573Z
2022-03-04T21:47:45.573Z
blacksmith37
<p>So, I am mixing up a substrate from peat and perlite,50%/50%, and I am adding some dolomite lime and gypsum as additives, as vermaculite is too expensive to substitute for the perlite.</p>
<p>As I am unable to find granular gypsum, my question is if I can use something that is sold in hardware stores around here as a substitute - it is very cheap and is called &quot;construction gypsum&quot;. It is sold in 10 kilo bags and after mixing with water hardens for a minute or two.</p>
<p>I would also like to know what is the best way to add silica to the substrate, as I have found an additive that is called rhino-something, but it is only for flowering, as it contains potassium, as I understand.</p>

<soil>
Can I use building gypsum as a soil additive?
aaa
# Can I use building gypsum as a soil additive?

(Asked by: username_0 on 2022-03-04)

So, I am mixing up a substrate from peat and perlite,50%/50%, and I am adding some dolomite lime and gypsum as additives, as vermaculite is too expensive to substitute for the perlite.

As I am unable to find granular gypsum, my question is if I can use something that is sold in hardware stores around here as a substitute - it is very cheap and is called "construction gypsum". It is sold in 10 kilo bags and after mixing with water hardens for a minute or two.

I would also like to know what is the best way to add silica to the substrate, as I have found an additive that is called rhino-something, but it is only for flowering, as it contains potassium, as I understand.

**Tags:** soil


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## 1 answers

### Answer by username_1 on 2022-03-04. Score: 2

Apparently building gypsum is also known as Plaster of Paris. I put a few tons of gypsum drywall on a 1200 sq.ft. garden. It is free in some locations ( I got "bearings" - 6" X 48" strips- in a small railyard). I wanted to acidify my clay soil. Over winter the paper on each side, got wet and came off so I had to pick up and discard paper . In spring , I rototilled with a serious ( Howard Gem, 18 Hp Wisconsin) borrowed rototiller. So it was messy , some work, but free. An alternative is plaster of Paris power in a bag as you describe, very neat but costly in quantity. So you can add gypsum but what isthe objective, to add sulfur ? I was trying to change pH, that was relatively ineffective with gypsum.

> **Comments:**
> **username_0**: I don't know as I am following a recipe, but I think that, yes, it is to add sulphape ions, as the dolomite lime will raise the pH. What I am askin, I guess, is if such gypsum contains other unwanted additives. And by the way, it is not plaster  
> **username_1**: Gypsum is calcium sulfate , should be no additives unless marked as such.  

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