Lime & pH

• The purpose of adding lime to soil is to raise its pH, making it less acidic. For most turf-type grasses, the ideal pH range is between 6.0 and 6.5. Soil with a lower pH can benefit from lime, but red clay is not necessarily acidic.
  
  

Clay Soil

• David Goforth of the North Carolina Cooperative Extension recommends lime as one of several improvements to red clay soil, noting that North Carolina soils are typically acidic. Red clay, however, is not universally acidic.
  
  

Soil Testing

• The best way to know whether or not you should add lime to your lawn is to get a soil test. This will tell you the pH of your soil, as well as its nutrient levels. Regardless of pH, red clay can almost always benefit from the addition of compost, manure and other organic materials.