Clay soil is a sticky mess when it rains, and it tends to hold onto water far too long; those clay particles just stick together in a glue-like mass. Improving clay soil means reducing the volume of clay by adding other materials in the soil. You can amend your soil to improve growing conditions in a large area of lawn with clay soil or tackle smaller trouble spots.
Improving Large Areas
Measure the area of your lawn that you want to improve. Get the measurements for length and width in feet, then multiply these two numbers to get the total area in square feet. It's best (and makes more sense) to improve as large an area as you can.
Determine how much coarse sand and coarse organic material (such as compost) you need to cover the area you want to improve. A 3-inch layer of each is a good idea, according to Bachmans.com, and one cubic yard of each material will cover about 100 square feet at that recommended depth.
Till up the area to be improved and remove any clumps of grass or weeds. Till as deeply as you can with a standard garden tiller (around 12 to 18 inches).
Spread the organic matter over the area and work it in to the top layer, about 6 inches deep, with a rake.
Spread the sand over the area and use a tiller to work it in to the soil mixture.
Use a rake to even out the area once it has been completely tilled. Spread grass seed and cover with hay or lay sod. Water thoroughly.
Keep an eye on drainage issues as the new grass grows into place. If you see the same problems, this means that your soil still has too much clay and will need to be amended again. Amend the soil once a year as long as you see drainage issues, and introduce more trees and shrubs, as their extended root systems help break up the soil and improve drainage long-term.
Improving Small Trouble Spots
Add lime. Lime helps break down clay in the soil and improve drainage ability, according to the editors of The Big Book of Gardening Skills. Beware, however, that lime will make soil more alkaline (increase its pH level); test your soil first to determine the pH level, and use lime sparingly if it is already somewhat alkaline.
Plant a clay-tolerant shrub, such as arborvitae or forsythia, and then mulch over open areas that won't grow grass. Root growth helps loosen the clay soil that, left on its own, tends to form a tight crust, according to The Big Book of Gardening Skills. Mulching these areas will help prevent crusting, allow water to slowly seep into the soil, and by slowing down the water will help keep the clay from becoming sticky and muddy.
Add coarse sand, crushed gravel or well-rotted sawdust. Rake up the area to loosen the soil, spread out a 3-inch layer of the material to add, and work the new material into the loosened soil. For more drastic drainage problems, working in small gravel or crushed gravel has the same effect as sand but to an even greater degree. Sod or reseed and water well after mixing in the soil amendment.
Work in manure or compost to improve drainage and to improve the nutrient levels in the soil.
About this Author
Annie Mueller is a writer, editor, professional blogger, website designer, and tutor. She attended Missouri Baptist College and earned her Bachelor of Arts in English from Mississippi State University, with a Summa Cum Laude standing. She has written extensively on gardening, parenting, education, and personal growth for women.