Gypsum can be applied to the soil directly or through the irrigation system. Gypsum suitable for land application varies in purity and particle size. Effectiveness of gypsum increases with fineness. Gypsum particles unable to pass a No. 8 sieve dissolve too slowly to be effective. Gypsum that is pulverized reacts quickly, but is dusty and may be difficult to spread.
Fine particles result in better uniformity than large particles.
Several irrigations are required to dissolve gypsum, therefore the particles may be visible in the turf for some time. Gypsum generally does not burn foliage. The amount of gypsum required to decrease soil sodium is dependent on the exchangeable sodium percentage and the cation exchange capacity of the soil. Application rates typically range from 20 to 50 pounds per 1000 sq. Light frequent applications are more effective than heavy infrequent applications, especially in sandy soils.