January and February are busy months for soil testing here at the extension office.
Most people have some free time to prepare their lawns and gardens for the upcoming spring planting.
One of the most important results you receive with your soil test is your soil's pH and the amount of lime that should be applied to correct it.
So just how does applying lime help adjust your pH?
First, let's discuss pH. Reaction of soils is measured by the amount of hydrogen ions in the soil, which is expressed as a number on a scale of 1 to 14.
A pH of 7.0 is considered neutral.
Anything below 7.0 is considered acidic, and anything above 7.0 is said to be basic or alkaline. Most of the native soils in our area tend to be acidic, usually less than 6.0.
Most of our lawn grasses, as well as many vegetable and ornamental plants, thrive best in soils with a pH range between 6.0 and 7.0.
The biggest problem with acidic soils is that they contain low amounts of calcium and magnesium, two important minerals for plant growth.
Also, soils with low pH cause other nutrients, such as nitrogen, potassium, phosphorus and sulfur, to become unavailable for plant uptake.
To counteract the harmful effects of acidic soils, we can raise the pH by adding lime.
Lime is a compound of calcium and magnesium that comes in several forms.
Almost all lime used in the United States is ground limestone. It is almost pure calcium carbonate and is readily available and relatively cheap.
A similar product, dolomitic limestone, is used to describe limestone containing large amounts of magnesium.
The biggest downside to ground lime is in its application. It is most often found in powder form, which can be difficult to spread, and tends to stick to surfaces like driveways and patios.
Another form of ground limestone that is often a good choice for homeowners is pelletized lime. It can be found at hardware and farm supply stores in convenient bags. The main advantage of pelletized lime is that it can be easily applied through a broadcast spreader and will not stick to patios and driveways. It is also easier to spot-apply to specific areas than is the powdered lime.
Pelletized lime can change your pH faster than ground limestone, so it may be a better choice if you have waited a little too long to test your soil. The main drawback of pelletized lime is that it costs more than ground limestone.
Hydrated lime and burned lime are two lime sources you might encounter. Both can be caustic and are difficult to apply. I would not recommend these to any homeowner.
The best time to apply lime is before planting, by incorporating it into your soil. Lime can take up to two years to move down 2 inches in the soil, so tilling it into your soil is the fastest way to get the lime in the root zone.
However, sometimes this is not feasible, as with lawns.
Lime can be spread evenly over the top of the lawn. It can be applied any time of year, but the most favorable times are fall, winter and early spring.
Ground limestone can take at least three months to begin to change your pH, so the earlier the better. Do not apply lime to turf coated in frost or wilted.
Lime can be a great resource for landscapes and gardens, but many homeowners often apply too much. It is best to avoid yearly liming without soil test results. This may result in a pH that is too high, which is just as harmful to plants as an acidic soil.
If you have an ongoing soil pH issue, it is best to test your soil every two to three years.
Heavy rainfall, excessive nitrogen fertilizers and soil amendment use will all cause gradual acidification of your soils.
Clark MacAllister is the Dawson County extension agent. For more information, call (706)265-2442.