So the question was how to amend the soil. The landowner asked whether he could add gypsum or sulfur to correct the salinity-sodicity problem. Gypsum generally is added to provide either calcium to displace sodium or sulfur to enhance soil acidification. Gypsum is calcium sulfate, 22.5 percent calcium. Most Montana soils east of the Continental Divide already are saturated with calcium carbonate.
Sugar crystals form almost instantly on the bottom of the glass.
When you add gypsum to a soil already saturated with calcium, the calcium in the gypsum pushes more calcium carbonate precipitation. If you add sulfur, there is a very good chance of acidification and release of hydrogen, which will cause formation of sulfuric acid and a displacement of the sodium, which will then be replaced by calcium. Without adequate drainage and good water to move the sodium out of the soil, little reclamation is gained by adding sulfur. When attempting to reclaim a saline, sodic or saline-sodic soil, you first need good drainage, an outlet to send the sodium to when it is displaced. You might get a short-term surface response to sulfur, due to a temporary lowering of the pH, the release of some sodium and temporary improvement of soil structure.