According to the Ohio Department of Natural Resources, there are more than 400 identified types of soil in Ohio. Many of these are alluvial soils transferred by glaciers in which a lawn will thrive, but some are heavy clay soils that make growing a good lawn difficult. Clay soil is sticky when wet and rock-hard when dry. It contains closely spaced particles that do not drain well. The best way to improve clay soil is to break it up and improve drainage. One way to do this is to apply a soil amendment called hydrated calcium sulfate. This amendment is also known as gypsum.
Have a soil analysis performed on your soil. Although the Ohio State University no longer offers a soil testing laboratory through its community and continuing educational center, surrounding states, including Kentucky, Pennsylvania and Michigan, will test your soil for a fee. Contact your local Ohio State University county extension office for information on how to take a soil sample, and get recommendations for laboratories that will perform the soil test. Be certain to specify that your test is for soil in a lawn, and request gypsum recommendations with your test.
Purchase granulated gypsum in the volume recommended by the soil test. Applications of gypsum may range from 40 lbs. per 1,000 square foot up to 175 lbs. per 1,000 square foot.
Time your application of gypsum for early spring, along with nitrogen fertilizer (10-0-00). Pour a mixture of one part gypsum and one part fertilizer into a broadcast spreader. Use amounts based on the application directions for the fertilizer packaging and the recommendations for gypsum in Step 2. The amount will vary based on the size of your lawn. Fertilizer application rates vary between fertilizer brands. Push the spreader over your lawn in an even path, much like pushing a lawn mower.
Water your lawn thoroughly to soak gypsum into the yard. There should be 1 inch of standing water on your lawn when you finish watering.