Gypsum is a natural occurring calcium sulfate that can provide calcium to soils without affecting the pH. Gypsum is said to lighten compacted heavy soils. Gypsum can also be used in the barn cuter to preserve volatile nitrogen in manure. Recent studies suggest that applications of Gypsum on lawns may mitigate problems with turf pests such as grubs and chinch bugs. Gypsum contains 23 percent calcium, 19 percent sulfur, and trace amounts of potassium and magnesium. Gypsum is a feed grade material and can be used as a calcium supplement.