Gypsum

T

Tim1987

Well-Known Member
meangreengrowinmachine said:
I need to buy about a ton of this (maybe literally) for my clay soil in my garden too!
Click to expand...
You need to test for dispersion first. Search " testing clay soil for dispersion "
Basically you place some lumps of clay in water, and see how fast it dissolves. If it starts dissolving, and starts to disperse through the water, your clay needs gypsum. Theres a standard dose / m2 too. Just hit up google.
If you dont get dispersion, or barely any, and it takes a long time. (generally hours) Then you need to add more organic matter.
There should be a guide for timing the tests too.
Its pretty simple really. Usually i just put my PEDS in a dish. Add a little distilled water. If i dont have dispersion within several minutes. Then i leave the sample overnight, and see how much its dissolved in the morning.

Hope this helps man.
Because adding gypsum to the wrong type of clay, wont do much at all. It could even be counter productive as well.
:peace:
 
Strudelheim

Strudelheim

Well-Known Member
Tim1987 said:
Its a fantastic amendment! I love it.
You dont use gypsum for the same purpose as lime. It doesn't alter your ph.
Whats so good about gypsum, is it buffers the soil, so the ph doesn't swing easily at all.

Say you have a soil thats ph 6.5. Well why use lime? The ph is fine.
Gypsum still provides calcium, as well as the benefits of sulphur. But buffers the soil to stay at 6.5. Its fabulous stuff. Really!
Gypsum also breaks up sodic, clay soil.
Click to expand...
Why do you say it buffers soil to 6.5?

AFAIK, Dolomite raises PH, thats what the carbonate part does. Because Gypsum doesn't have carbonate it does not raise it. It doesn't raise ph, or lower, or buffer it either in this magical 6.5 range you speak of. Maybe your mix was stable at 6.5 and the gypsum had no effect as it shouldn't compared to dolomite lime. That doesn't mean you should jump to the conclusion that it buffers!

I suggest this for people. Use dolomite if you want to raise ph, (once again it doesn't buffer it also raises and will keep going above 7). Use gypsum if your ph is in the desired range already.

Feel free to prove me wrong with some articles/studies stating otherwise, I have read my share hence my comments.
 
Strudelheim

Strudelheim

Well-Known Member
NaturalFarmer said:
I have done a few experiments with gypsum and have found that too much in my mix gives a very nasty aftertaste to the smoke.
I ran four mixes in 2 cup increments and only really found awful taste beyond 6 cups of gypsum to 35-45 gallons of soil (45 gallon bags mostly full). 8 cups was almost unsmokeable (I smoked all of it).

2 cups per grow on a large plant should be enough but 4 cups was the sweet spot for my mix.
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Interesting. makes me think about what other amendments would have an effect on taste at too high of inputs.

Also, 45G =6 cubic feet, and at 6 cups total that is 1 cup per cubic foot for everyone making mixes I wanted to simplify. Natural farmer is saying he has had negative results going above this amount! Which would be easy to do for most as 1 cup per cubic foot of DL is used so if someone is substituting they would easily use 1 cup of gypsum instead. Ive been using 2/3 cup on my recent mix so I seem to safe.

Thanks
 
T

Tim1987

Well-Known Member
Strudelheim said:
Why do you say it buffers soil to 6.5?

AFAIK, Dolomite raises PH, thats what the carbonate part does. Because Gypsum doesn't have carbonate it does not raise it. It doesn't raise ph, or lower, or buffer it either in this magical 6.5 range you speak of. Maybe your mix was stable at 6.5 and the gypsum had no effect as it shouldn't compared to dolomite lime. That doesn't mean you should jump to the conclusion that it buffers!

I suggest this for people. Use dolomite if you want to raise ph, (once again it doesn't buffer it also raises and will keep going above 7). Use gypsum if your ph is in the desired range already.

Feel free to prove me wrong with some articles/studies stating otherwise, I have read my share hence my comments.
Click to expand...
It doesnt really alter the ph at all. Its not a soil sweetener. I believe i stated that as well.

Whats so good is gypsum makes it very hard for the ph to swing out of range. It is a buffer in this sense to me. But you're right its definitely more of a soil conditioner.

Ph6.5 was an example of when i personally wouldnt lime, and gypsum would be my go to amendment, and calcium source.
If acidity is high. Its not that it magically holds the ph there. But it helps make things available that otherwise wouldnt be.
It can really help in forming magnesium sulfate. Also helps acidity in many other ways.

The calcium and sulphur cancel each other out so ph isnt altered.
But.
Depends on your % base saturation of calcium and magnesium, and how much of your soils CEC is calcium already.
Because its generally CEC that affects hydrogen levels in the soil (ph).

:peace:
 
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T

Tim1987

Well-Known Member
Strudelheim said:
Why do you say it buffers soil to 6.5?

AFAIK, Dolomite raises PH, thats what the carbonate part does. Because Gypsum doesn't have carbonate it does not raise it. It doesn't raise ph, or lower, or buffer it either in this magical 6.5 range you speak of. Maybe your mix was stable at 6.5 and the gypsum had no effect as it shouldn't compared to dolomite lime. That doesn't mean you should jump to the conclusion that it buffers!

I suggest this for people. Use dolomite if you want to raise ph, (once again it doesn't buffer it also raises and will keep going above 7). Use gypsum if your ph is in the desired range already.

Feel free to prove me wrong with some articles/studies stating otherwise, I have read my share hence my comments.
Click to expand...
Just found this on Google for you. Enjoy the read.
Has the chemistry information as well.
:peace:
 
T

Tim1987

Well-Known Member
Strudelheim said:
Why do you say it buffers soil to 6.5?

AFAIK, Dolomite raises PH, thats what the carbonate part does. Because Gypsum doesn't have carbonate it does not raise it. It doesn't raise ph, or lower, or buffer it either in this magical 6.5 range you speak of. Maybe your mix was stable at 6.5 and the gypsum had no effect as it shouldn't compared to dolomite lime. That doesn't mean you should jump to the conclusion that it buffers!

I suggest this for people. Use dolomite if you want to raise ph, (once again it doesn't buffer it also raises and will keep going above 7). Use gypsum if your ph is in the desired range already.

Feel free to prove me wrong with some articles/studies stating otherwise, I have read my share hence my comments.
Click to expand...
If want to find which type of PEDS you have in your soil, so you know whether you need to amend with gypsum.
This may help a little.

Tim1987 said:
You need to test for dispersion first. Search " testing clay soil for dispersion "
Basically you place some lumps of clay in water, and see how fast it dissolves. If it starts dissolving, and starts to disperse through the water, your clay needs gypsum. Theres a standard dose / m2 too. Just hit up google.
If you dont get dispersion, or barely any, and it takes a long time. (generally hours) Then you need to add more organic matter.
There should be a guide for timing the tests too.
Its pretty simple really. Usually i just put my PEDS in a dish. Add a little distilled water. If i dont have dispersion within several minutes. Then i leave the sample overnight, and see how much its dissolved in the morning.

Hope this helps man.
Because adding gypsum to the wrong type of clay, wont do much at all. It could even be counter productive as well.
:peace:
Click to expand...
As well as a soil texture assessment. I like forming a bolus, to check for loam. Then ribbon test the bolus to check for clay.

Combining this with testing for dispersion, and soil ph. Gives a really damn good idea of the soil amendments you need.
:peace:
 
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