“I have a problem with deep cracks forming in my lawn soil, especially when it is dry. The cracks can be quite large, and I don’t know what to do. Please advise!”
-Naser

Large cracks form in soils that are high in clay. The clay particles act just like a sponge – they swell as they soak up water, and they shrink as they dry out. During a dry spell, the shrinkage can be so significant that large cracks can form. In severe cases, these soils (called “expansive soils”) can undermine the foundations of buildings because they swell and shrink so much.

Clay soil can be tricky because once it dries out in the heat, it can become hard as a rock – that’s why they make bricks and pottery out of this stuff! Simply adding water doesn’t solve the problem – you need to amend the soil in order to correct the texture. Before adding anything to your soil, you first need to have your soil tested. Take samples to your local agricultural extension service, or purchase a soil test kit that you can send to a lab, in order to determine the exact makeup of your soil.

If you indeed have clay soil, I’d suggest that you first try aerating your lawn, then top-dressing with compost. As the compost breaks down, it will actually improve the texture of your soil. You’ll have the added benefit of organic nutrition for your yard. You’ll probably need to do this more than once, and if your soil is heavy clay it may need to become part of your lawn care practice every few years.

If your soil test indicates that your clay soil is “sodic” or high in sodium, you can apply gypsum or lime. This replaces the sodium with calcium, which reduces the crusty texture of the soil. However, it only works if you have sodic soil.

The Arizona Geological Survey has a great resource with photos and information about expansive and problem soils.

Further Information

• Top-Dressing to Improve the Soil in Your Lawn (article)
• Breaking up Clay Soil (article)
• What is Dirt, Anyway? (article)
• Soil Evaluation (video)
• Soil Test (video)

Hope this helps!

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