The main reason for using Horticultural Gypsum is to clean exchange sites in the soil of undedesireable elements namely soduim. However it also cleans away the desireable elements N-P-K etc. We use horticulture gypsum on swim pool water spills or overflows to leach out the salts and acids from the exchange sites. We must come back with a complete fertilizer to refill those elements that are disireable. This is the only way I apply gypsum with out a soil sample test. Then only because swimming pool water is a common problem in my area. OOPs also when we have bad storms and sea water floods.
You can lead a Donkey to water but you can't make the Jackass Drink
"As Americans you have the right to be stupid." John Kerry
"Life is tough, but it's tougher when you're stupid.” John Wayne.