Should I apply lime to my lawn?

FAQ
Question: 

Should I apply lime to my lawn?

Answer: 

In Iowa, home gardeners should apply lime to lawns only when recommended by a soil test.  A soil test will indicate the current soil pH and, if necessary, the amount of lime to apply to the area. 

The soil pH is important because it influences the availability of essential nutrients.  The pH scale runs from 0 to 14.  Any pH below 7.0 is acidic and any pH above 7.0 is alkaline.  A pH of 7.0 indicates a neutral soil.  The optimum pH range for lawns is between 6.0 and 7.5.  Lime is applied to acidic soils with a pH below 6.0 to raise the pH into the optimum range.  However, an application of lime to an alkaline soil can raise the soil pH to excessively high levels, reducing the availability of plant nutrients and leading to poor plant growth. 

There is no need to apply lime to most lawns in Iowa as few have a soil pH below 6.0.  Applying lime to lawns with a soil pH above 7.0 may actually be detrimental.