If you were about to start a landscaping project in your yard but were told to add lime to the soil, even though you aren't planting anything, you might want to listen to that advice. Many homeowners think that adding lime to the soil is purely for amending the acidity to make the soil more hospitable to certain plants. People don't often know that lime is a prime source of stabilizing material for unstable soils. "Unstable" soil can be anything from the soil above an earthquake fault to soil that reacts to moisture and temperature changes, and all of that can make your landscaping plans impossible unless you stabilize the soil with an extra substance like lime.
Thick Soil Doesn't Equal Stable Soil
The ground in your yard might seem nice and stable, especially if you have thick clay that makes digging into the soil difficult. However, even that thick clay isn't stable just based on how tough it seems to you. Clay and other soils can be extremely reactive to things like changes in moisture; picture all those images you've seen of parched, cracked clay in drought-stricken areas. Temperature, too, can make soils expand and contract, and that motion can wreak havoc on anything buried in the soil, from pools to posts.
Stability can also be a problem for highly absorbent soils that drain well; these can become muddy very easily and need something that helps keep them a little drier and thus more stable, so things don't shift and fall over in that soil.
So even if you aren't anywhere near a quake fault and have soil that is resistant to any dents you try to make in it, that doesn't mean it passes the stability requirements for things like installing pools, fences, terrace walls, and more. The solution is to mix the soil with something that will tame that reactiveness and keep the soil drier, thus offering more support for anything you put in the ground.
Lime is one such material. While the clay or other soil particles will still react as they always have when the moisture levels or temperatures change, those particles will be mixed with lime, so the more-reactive and less-reactive materials will be more evenly distributed and thus have a smaller effect should they move or change. The effects of clay expanding in response to moisture will be less pronounced, for example.
Lime Affects Soil pH
Do keep in mind that adding lime will still affect the pH of the soil. If you plan to plant anything near the landscape you're changing, be sure to look for plants that like alkaline soils, and keep getting pH tests so that you know how the pH is changing over time.
Soil stabilization isn't something you want to do on your own because this involves bringing soil up to construction-worthy standards. Look for companies that can use lime to make the soil in your yard able to support swimming pools and more.
For more information about lime stabilization, contact a local landscape contractor.