Can someone fill me in on the difference between lime and gypsum. I have used both in the past, lime as a regular maintenance item and gypsum to remediate compacted clay type soil. Not sure I was using it correctly but it gave the results I was looking for. My understanding is that they both lower the PH of the soil but that gypsum does it more effectively. Am I on the right track or did I miss the train all together? A local sod producer is telling me that gypsum is no more effective than lime and therefore a waste of money.