Nearly every homeowner understands the importance of applying lime to their property but a complete understanding of why liming can be an important aspect of a lawn care program is also necessary.  The primary issue is how to determine if liming is needed and how one should apply the lime.

Lime is applied to the soil to increase the soil pH.  Soil pH, a measure of the soils acidity or alkalinity, can directly influence the vigor and quality of the the lawn.  When the pH is below 7.0, the soil is acidic – When it is above 7.0 it is alkaline.  For turfgrass, a soil pH between 6.0 and 6.8 is ideal.

Several factors cause the formation of acidic soil conditions.  The primary cause is the leaching of nutrients such as calcium, magnesium and potassium from the soil.  Another cause is the use of acidifying nitrogen fertilizers.  Most of the fertilizer applications will affect soil pH in a number of ways including:

• Type of nitrogen applied
• Amount applied
• Types of nutrients present in the fertilizer
• Soil type
• Irrigation frequency

When the soil pH drops below 6.0, a number of nutrients necessary for proper growth become less available for use by the turfgrass.  These nutrients include:

• Nitrogen
• Phosphorus
• Sulfur
• Calcium
• Magnesium

As these nutrients become less available, the lawn’s color, vigor and ability to resist or recover from heat, drought or stress will be reduced.  Applications of enough lime to raise the soil pH above 6.0 can increase the availability of these nutrients, making it easier to maintain the quality and vigor of the lawn.  The key to the liming process is utilizing a soil test to determine whether or not liming is needed plus how much lime will be required to reach the desired pH.  A state or commercial soil testing laboratory can perform the test and make accurate recommendations based upon the soil report. 

**NOTE: A soil pH above 8.0 is just as undesirable as a pH below 6.0.  When in doubt, utilize a landscape company or soil testing facility to provide you with the correct information for liming and fertilization – not all lime materials and fertilizers are created equal.  Guessing can cause more harm than good.