@viva_oldtraffordviva_oldtrafford said: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).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.
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.