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Gypsum have you used it, did it help fix your problem, and what brand would you recommend?

6818 Views 26 Replies 11 Participants Last post by  ErosionWizard
From what I've read gypsum is a great way to increase your calcium and sulfur levels without increasing your ph. I've found one brand that seems to be a winner but they have no dealers close by (supercal so4). So I'm curious what is your experience with it and do you have a brand you feel works good?

I'm specifically thinking of using it to stop dog urine from killing my grass. I've done some research and basically once ask the nitrogen from dog urine is absorbed salts are absorbed with it. This in turn pushes water out dehydrates the grass and kills it. Supposedly good gypsum will pull the salt out add calcium and sulfur which will help with water retention in the grass.

I might turn this into a blog/ journal if it gets enough interest.
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viva_oldtrafford said:
Colonel K0rn said:
I've been using gypsum to correct a high salt content that's occurring in my perched water table, aka, water stands on my soil when it rains, and it can't get past the sodium barrier that has formed and percolate into the lower "dry sand" that's subsurface. As for the dog pee, it's the high concentration of urea that's in the urine that's causing the burns; same thing would happen if you spilled ammonia in one concentrated area or dropped a pile of fertilizer in that area. @Spammage linked some dog treats that he gives his dogs to help with the urine burns on the grass from his doggies. Aside from following your dog around, and immediately flushing the area with water to dilute the urine, the treats seem promising.
CaSo4 won't fix a salt issue, it is a soluble salt in soil (Ca is a divalent cation - K,Mg,Na are also mono/di valent cations - aka salts). CaSo4 (gypsum) is a remedy for sodic soils (soils with elevated Na) because Na is a monovaent cation and it (Ca) knocks the monovalent cation off the exchange cite. A lot of lcp recommend gypsum, but for most of thier clients, it's snake oil....and in fact it Is only increasing the soil salinty (a big issue if you have a less tolerant Ece turf type).

Gypsum is a great product for soils with elevated Na (helps flocculate clay particles, and flushes Na) aside from that, it has no place in a turf management program.
Gypsum does indeed fix salt issues for the exact reasons you stated, and it's not really disputable or anything to get upset about. I've applied many thousands of tons of the stuff to deal with sodium, magnesium, and even one case of extreme potassium. It's been used in agriculture since at least Ben Franklin (i got curious when I saw a bag of Ben Franklin Brand Gypsum).It certainly can raise your soil E.C. in some rare instances. But fortunately we don't have to guess. The salt index of gypsum is 8.1, potassium chloride is 116.3, potassium sulfate is 46.1, sodium chloride is 153.8, urea is 75.4, superphosphate is up to 10.1. So, while calling gypsum a salt is true, saying that will increase salinity is pretty misleading considering the other things we put on our lawns. What's more, calcium is just fantastic for soil and plants, and sulfur is actually becoming more and more deficient due to the Clean Air Act. Calcium helps plants fight of bacterial and fungal infections, and in combination with phosphorous (not tank mixed) is way better than phosphorous alone for root development.
Here's a few of the equations I use for different situations:
I use this equation if I need to unload sodium or magnesium form the soil: (NA+MG)-CA)*1000= lbs. gypsum/ac
I use this equation if I have a clingy soil with high CEC: [(SAR-5)/100]CEC*1.7= gypsum addition
I use this one if I need to adjust sodium adsorption ratio: [(ESPa-ESPd)*CEC]*1.7= tons gypsum/ac*ft soil
Sometimes I just skip the calcium and go straight to elemental sulfur or straight up sulfuric acid.
I have all kinds of rules on when to use certain calculations and certain rates, so it's not really plug and play.

But to get to the OP's question about brands. I don't know of any brands other than the Ben Franklin and GypSoil brand. All I know is I prefer the mined stuff to the recycled drywall stuff that may or may not contain contaminants.
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Well I am a certified professional soil scientist with the soil science society of america, and have other credentials, but seriously doubt that i'm the smartest guy in the room. Yes, salt problems can only be fixed by leaching, that is true. Sulfuric or n-furic acids do a different job than gypsum. They aren't really interchangeable like that.
The point is that gypsum is far from "snake oil" whether you are growing turf, trees, row crops, or whatever. It serves a legitimate purpose for certain issues, not all issues. Use the right tool for the job. Saline soils by definition have e.c.'s >4dS/m- you aren't growing much of anything in those conditions and yet the entire California agricultural industry relies on gypsum not because they are all saline soils but because soil doesn't have to be saline to benefit from gypsum.
I'm speaking from a lot of first hand experience, sodium is not the only ion that gypsum will work on for the exact reasons that you've already stated, calcium has higher affinity to the ecxchange sites than magnesium, potassium, hydrogen, and sodium, and potassium sulfate is stable as is magnesium sulfate, and sodium sulfate
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I'll try one last time. You can't leach anything through a soil clogged up with sodium or other cations with big hydrated radius's. Use calcium to get it off the soil then start leaching. That is how it works regardless of your understanding of the issue. Thanks for the warm welcome!
Spammage said:
Let me preface this by stating clearly for the record that you guys would qualify as experts long before I would with your education, experience and background.

I live on the East side of DFW where we have notoriously bad calcareous clay soil. We also have the bonus of being able to irrigate with highly bicarbonate water. If the soil dries, a nice white crust is left behind. There is so much free calcium in the soil that it could never qualify as sodic (or probably even saline) based on percentages.

A couple of years ago I went back and forth about whether gypsum applications would help. The producer says yes, but most experts say no. It isn't expensive, so I bought and applied to the lawn with heavier application in areas that would not drain after a rain. The next rain of 2"+ in about an hour ponded, but was gone by the next morning. After a few subsequent apps, the pooling is gone within 30-45 minutes.

I'm not going to say that the gypsum is the only change that's been made, but I saw an immediate improved response after the first app. Based on my real world experience, I would say that the jury is still out as to exactly which soils can be improved and to what extent by gypsum applications.

I'm glad you are both here, more knowledge is always a good thing.
I'm starting to forget a lot of this stuff since we moved to the east coast and don't have to deal with calcareous soils anymore but... any high bicarbonate water i've seen that would leave deposits always had pH's over 8.0 and the fix was n-Furic or sulfuric injection in the water down to the proper pH. Not really practical for the homeowner. I've read that bicarbs are more toxic to plants than even chlorides, but have never seen it firsthand. I'm not sure if you are on gypsyferous soil, which i'm Less familiar with, or a free lime containing soil, but what you might have done is adjust up your Ca saturation percentage with the gypsum addition which can help with drainage. Soil report would tell the tale.
Like viva said gypsum is technically a salt as would be lime. However they have different solubilities, which is a big reason why gypsum gets used at all. Lime is something like 42% calcium and gypsum maybe 24% calcium. To put a pound of calcium into solution from lime requires ~750 gallons of water, for gypsum it's much less at around 80 gallons of water. If anybody has used any of those liquid lime products which I think are pretty handy products, that lime is only in suspension not solution because the package size would have to be pretty big. Definitely need two hands to lift it😎
In other words, gypsum brings up soil calcium way quicker than lime even though it can contain half as much calcium
No that's not true at all, Calcium chloride, calcium thiosulfate, calcium carbonate, calcium sulfate, calcium nitrate are all valid calcium forms that come to mind for calcium nutrition. Though only caco3 is a pH adjuster. Calcium isn't very plant mobile, and I wouldn't trust it as a foliar or trans laminar fertilizer. It gets short shrift as a nutrient because it's effects are not visibly noticeable in most crops.
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