Bermuda grass is a popular warm-season turf known for its drought tolerance and aggressive growth, but its performance is deeply connected to the soil’s chemical balance. This turf is sensitive to extreme soil conditions, which can block its ability to absorb necessary nutrients. Lime, an agricultural amendment typically composed of ground limestone, functions primarily to raise the soil’s pH level. Applying lime is only beneficial when the soil is too acidic and the pH needs to be increased for optimal growth.
Optimal Soil Acidity for Bermuda Grass
Bermuda grass performs best in a soil environment that is slightly acidic to neutral. The ideal soil pH range for this warm-season grass is between 6.0 and 7.0. Maintaining the soil within this window maximizes the turf’s health and appearance.
This slightly acidic range is optimal because it unlocks the availability of essential macronutrients. When the pH is too low (highly acidic), elements like nitrogen, phosphorus, and potassium become less soluble, making them difficult for the roots to absorb. Keeping the soil near the 6.3 to 6.5 mark allows the grass to efficiently take up these components. This maximized nutrient uptake allows Bermuda grass to develop a dense, vibrant green appearance and strong root system.
The Role of Lime in pH Adjustment
Lime, primarily calcium carbonate (CaCO3) or dolomitic lime (containing magnesium carbonate, MgCO3), is an alkaline material used to neutralize soil acidity. Soil becomes acidic due to natural processes like rainfall, nutrient leaching, and the use of certain nitrogen fertilizers, which increase the concentration of hydrogen ions (H+). The carbonate component of the lime reacts with water to produce a mild alkali, which neutralizes the excess hydrogen ions.
This chemical reaction increases the concentration of hydroxyl ions (OH-) in the soil solution, elevating the pH level. The process is slow and gradual, often taking several months to a year to fully change the soil chemistry. Lime’s function is corrective, adjusting the soil’s reaction to create a more favorable condition for nutrient dissolution and microbial activity.
Why Soil Testing is Essential
Applying lime without a soil test is speculative and can easily harm the turf, making soil testing the most important step. If the soil pH is already optimal or too high, adding more lime pushes the soil into an alkaline state. This can induce nutrient deficiencies, most notably iron chlorosis, where iron becomes insoluble and unavailable, causing the grass blades to turn yellow.
A professional soil test provides two critical values: the soil pH, which indicates if lime is needed, and the buffer pH, which determines the required amount. The buffer pH measures the soil’s capacity to resist a pH change; clay-heavy soils require significantly more lime than sandy soils to achieve the same result. Soil samples should be collected as a composite from multiple spots and sent to a reputable lab, with testing recommended every one to three years. The lab report provides a precise recommendation in pounds of lime per 1,000 square feet, removing guesswork from the process.
Techniques for Applying Lime
Once a soil test confirms the need for lime and provides the application rate, proper technique is necessary for effectiveness and safety. Lime is available as a fine powder or as granular, pelletized limestone. Pelletized lime is preferred for lawns because it is less dusty and flows more evenly through a standard broadcast or drop spreader, ensuring consistent coverage.
The ideal time for application is in the fall or late winter, allowing the amendment maximum time to neutralize soil acidity before the Bermuda grass’s active growing season begins. Since lime is slow-acting, applying it when the turf is dormant allows the chemistry to work without interfering with fertilization. Never apply more than 50 pounds of lime per 1,000 square feet in a single application, as heavy doses can burn the grass and are less effective. After spreading the material evenly, water the lawn thoroughly to wash the lime particles into the soil, initiating the pH adjustment process.