by james ellison:
http://jellison.wrytestuff.com/swa15796.htm

Just spread it on the lawn, using the granular type, with a lawn spreader at the rate of 40 pounds per thousand square feet. Gypsum fertilizer can be spread any time of the year and only one application per year is needed. To get it started working, water immediately after applying. If applied properly it does not affect the pH of the soil, not harmful to humans and your animals and will not burn. And because Gypsum is neutral and will not change the soil pH, you can use it in places where plants like Azaleas, Camellias, Rhododendrons and other acid loving plants grow, they need a little calcium too. Of course, gypsum should be applied per directions.