Soil is made up of a mixture of three components: sand, clay and loam. The size and shape of the individual soil particles determines which kind it is. Sand has large particles and is loosely packed, while clay is made up of small particles that are tightly packed together. Because of this, clay drains poorly and is slippery in wet weather and rock hard in dry weather. The best way to improve predominantly clay soil is to turn it into loam by mixing it with organic, loamy amendments.
Break up your soil in spring after it dries but before it becomes rock hard. Loosen soil down to a depth of 12 inches. This is the average depth of most topsoil.
Select organic soil amendments. Good organic amendments include compost, manure, wood chips, clover, hay and straw. These amendments will aerate the soil as well as break down into nitrogen-filled loam.
Spread enough organic amendments over the surface of your soil to change the ratio of clay and loam present in the soil. Typically, most universities recommend that you spread a 4-inch layer of organic amendments, or 2 cubic feet per 1,000 square feet of soil, over the clay yearly to gradually reduce the number of clay particles in soil.
Mix the organic amendments with the soil using the rototiller. The amendments must be thoroughly mixed into the soil to change the soil's structure.