Art Wilson Company Provides Additional Information on Calcium Sulfate: To read the report provided to PACE Turf by Art Wilson Company click on the link below:
http://www.paceturf.org/PTRI/Document...

Use of gypsum in soil applications and water treatment is a standard practice for managing soil sodium. There is some confusion, however when it comes to selecting gypsum products because there are many different products being marketed for sodium management some of which contain gypsum and others that do not.

In this video, we look at products based upon gypsum and products based on a related material calcium sulfate anhydrite and we explain why their very different performance when dissolved in water is important when making your product selections.

For a printed report that describes the techniques used in this video in more detail, see this Super Journal article on gypsum vs. mined calcium sulfate anhydrite:
http://www.paceturf.org/index.php/jou...

For information on labeling of gypsum products in California, refer to: California Department of Food and Agriculture, Feed, Fertilizer, and Livestock Drugs Regulatory Services Notice of Fertilizer Licensees. Subject: Labeling of Gypsum Products. Labeling requirements for gypsum pursuant to Section 2302(i)(4) of the California Code of Regulations (40 KB pdf):
http://www.paceturf.org/PTRI/Document...

To evaluate dissolution rates, we utilized the following constant: 1 meq Ca/l = 0.085 dS/m (Carrow,R.N., Waddington,D.V., and Rieke, P.E. 2001. Turfgrass Soil Fertility and Chemical Problems. page 152.)