Troup extension agent: Liming: Why it’s important
Published 12:00 am Friday, January 8, 2016
One of the most frequently asked questions is why plants in the landscape are not growing well.
The most frequent response is: When is the last time that you soil tested? Soil testing is a diagnostic tool that can solve a lot of headaches.
The most important information on the soil test recommendation is the pH level. The pH level indicates the acidity or alkalinity level of the soil. Most plants require for optimum growth a pH range between 6.0 and 6.5, slightly acidic. The pH scale ranges from 0 to 14 with 7 being neutral.
Why is this important? If the pH is below 6, nutrients such as nitrogen, phosphorus, potassium, sulfur, calcium and magnesium become unavailable. What this means is that you can apply all the fertilizer you want and if the pH is below 6, the plants will not be able to use it. Roots will just not grow well. The plants will therefore be deficient in these nutrients.
Soils in Georgia are naturally acidic. If you plan on growing azaleas, rhododendrons, blueberries or broom sedge a low pH would be alright. Since most garden plants and landscape plants require slightly acidic soil, liming becomes necessary. It can take up to a year for lime to react in the soil so it’s essential that you do it as soon as you can.
Lime is ground up limestone rock. The two most common are dolomitic limestone and calcitic limestone (or high-cal). Dolomitic contains both calcium carbonate and magnesium. If your soil lacks magnesium you can kill two birds with one stone by applying Dolomitic limestone. Calcitic is almost 100 percent calcium carbonate.
Limestone is sold by particle size. The smaller the size particle, the quicker the product will neutralize the soil where the roots are pulling the nutrients. The powder-sized particles are more difficult to spread but react quicker. The sand-sized particles can be spread with most garden spreaders fairly easily.
Now is the time to soil test and apply lime for spring and summer plant growth. Liming is the most important step in a fertilization program.
What’s going on in Extension?
Tree seedlings can be ordered from the Georgia Forestry Commission, 706-845-4122
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