The role of gypsum in adjusting soil pH may be confusing. Incorn and soybean growing areas, soil pH in the range of 6 to 7 is preferred for optimal growth and yield. Soil pH encountered in most areas of the north-central region of the U.S.range from 5 to 8. Within the pH range of 4.5 to 8.4, the addition of gypsum will have no effect on soil pH. The reaction will be as follows: CaSO, + Sod2-t Ca2- Dissolving gypsum in water does not result in net change in soil water charge.