According to West Texas A&M University, adding sulfur to clay soil is a way to break up the tightly packed soil. The structure of clay soil means that it is poor in nutrients and will not drain. Sulfur can also be used to lower the pH of alkaline soils. You can determine if your soil needs sulfur by having it analyzed. A soil analysis is designed to determine the mineral content of soil.
To have your soil analyzed, dig soil samples from several places in your garden, and place them in clean containers. Take these containers to a laboratory, where technicians will analyze the content using scientific tools and chemicals. The report that they give you will list the composition of soil as well as give suggestions on the best amendments and how much of each amendment to add.
Consult the soil analysis results that were given to you by the laboratory that you took your soil to for analysis. The results will have suggestions that tell you how much sulfur to purchase for your soil. Sulfur rates of application will vary depending on your soil's pH and the tilth, which is a measure of how much clay is in your soil.
Put on protective clothing when touching sulfur to prevent getting any of it on you. Most sulfur exists in powdered form, which will absorb into the skin easily, and can accidentally be breathed in.
Break up your soil using a garden spade to a depth of 8 inches.
Spread sulfur over your soil to a depth of 2 inches with a shovel.
Mix sulfur into your soil with a rake.