Lime a Bermuda grass lawn is a way to raise the pH of the soil. Soil pH is measured on a scale of 1-14 with 7 being neutral. A soil pH below 7 is considered acidic while a soil pH above 7 is considered alkaline. Bermuda grass prefers a soil pH of 6-7. The pH of a soil is important because it affects the availability of different nutrients. Nitrogen in the soil is more available at a pH of 6 than a pH of 5, and liming would actually increase the nitrogen available to grass roots. In additions, a soil pH below 5 or above 7.5 can decrease the effectiveness of a slow release fertilizer.
The best way to determine your lawn's pH is to have your soiled tested. The soil test results will recommend the amount of lime needed to raise the pH to the optimal level.
Many southern soils are acidic and will need approximately 50 lbs of lime per 1000 square feet. Whenever possible purchase lime in pelletized form wince it is much easier to spread. Broadcast the limestone with a fertilizer spreader, or by hand. Lime can take up to 3 months to affect the pH of your soil and can be applied at any time of year. Since lime moves slowly in the soil, the best time to apply it is when planting immediately after aerating.
Occasionally, you may encounter an alkaline southern soil with a pH above 7.5. In such a case, you can lower the pH to the 6-7 range with an elemental sulfur product. The most common form of elemental sulfur is aluminum sulfate. It is often available in 50 lb bags and should be applied at the rate recommended on the bag.