Several factors help increase the amount of hydrogen in the lawn soil such as: Root respiration Nitrogen nutrition Decomposition of soil organic matter Leaching of calcium and magnesium from the soil by rain and irrigation When the amount of soil hydrogen becomes very high, soil is termed acid and lawn growth is reduced. The technician of Services Pro-Vert uses an instrument called a pH meter to test the acidity of your lawn soil. If the test indicates an acidic soil, add lime to reduce the amount of hydrogen that is detrimental to lawn growth. Never lime without a prior testing of soil acidity because if the soil is not acidic, adding lime (even a very small) creates an imbalance in lawn growth.