It may take several years to improve the soil’s physical condition and you’ll want to add more organic matter (in the form of composted materials, peanut hulls, rice hulls, grass clippings, etc.) periodically.
To improve clay soils, apply 1 to 2 inches of good sand and 2 to 3 inches of organic matter to the soil surface in late winter or early spring; then turn it under to mix it thoroughly with the soil. It may take several years to improve the soil’s physical condition and you’ll want to add more organic matter (in the form of composted materials, peanut hulls, rice hulls, grass clippings, etc.) periodically. Turn the soil to a depth of 8 to 10 inches — the deeper the better — each time you add organic matter. Add gypsum at the rate of 6 to 8 pounds per 100 square feet where the soil is heavy clay.