The best way to tell if a lawn needs lime fertilizer is to do a soil test that measures the pH. Soil that is more acidic will benefit from lime fertilizer.
There are a few ways to tell if a lawn is acidic and needs lime fertilizer. If there is an excess of moss or weeds, the lawn might be more acidic since moss and weeds thrive in acidic soil. If the soil is sandy, it is probably acidic and needs an application of lime. Soil that is like clay should also be fertilized with lime in order to reach a balanced pH.