Lime and Your Lawn...

Lime is applied to the soil of your lawn to increase the soil pH. Soil pH, a measure of the soil's acidity or alkalinity, can directly influence the vigor and quality of your home lawn. Here in the humid, eastern United States, rainfall often exceeds 20 inches per year, leaching basic or alkaline-forming ions such as calcium and magnesium from the soil. This results in an acid soil condition which restricts the growth of turf. The optimum pH level for turf is in the 6.0 - 6.5 range.

Lime is applied to soil, including that of home lawns, for the purpose of increasing the pH of the soil. Soil pH, a measure of the soil's acidity or alkalinity, governs the availability of many soil nutrients and can directly influence the vigor and quality of the home lawn. When the pH is BELOW 7.0, the soil is said to be acidic; when ABOVE 7.0, it is alkaline. For turfgrasses used in Ohio home lawns, a soil pH of between 6.0 — 7.0 (slightly acidic) is ideal.

Several factors are responsible for the formation of acidic soil conditions. One primary cause is the leaching of base nutrients such as calcium, magnesium, and potassium from the soil. This occurs more frequently in areas of heavy rainfall or on heavily-irrigated turfs. A second cause is the use of acidifying nitrogen fertilizers. Most of the fertilizers applied to lawns have the POTENTIAL to cause acidic conditions. However, the extent to which fertilizer application will affect soil pH is dependent on a number of factors, including: type of nitrogen applied, amount applied, types of other nutrients present in the fertilizer, soil type, and irrigation frequency. Other factors which may act to reduce soil pH are decomposition of soil organic matter and irrigation with acidic water.

When the soil pH drops below 6.0, a number of nutrients necessary for proper growth become less available for use by the turfgrass plant. These include the following: nitrogen, phosphorus, potassium, sulfur, calcium, magnesium, and molybdenum. As these nutrients become less available, the lawn's color, vigor, and ability to resist (or recover from) heat, drought, or traffic stress will be reduced. Applications of lime to neutralize the acidic condition and raise the soil pH above 6.0 can increase the availability of these nutrients, thus making it easier to maintain the quality and vigor of the lawn.

It should be noted that an excessively high (alkaline) soil pH (greater than 8.01 is just as undesirable as a low pH. When the pH exceeds 8.0, such nutrients as nitrogen, phosphorus, iron, manganese, boron, copper, and zinc become less available for use by the turfgrass plants in the lawn. The result may be a less vigorous, unhealthy lawn. Over-application of liming products may cause the development of alkaline soil conditions.