Within any given soil, there are two states of acidity that need to be accounted for before liming recommendations can be made. First is the active acidity, which indicates the current pH status of the soil. Active acidity accounts for the H+ ions in the soil/water solution that the laboratory measures. What active acidity doesn’t account for, however, is the reserve, or potential acidity. Think of a swimming pool that has a few people in it, those people represent the active acidity. Now, imagine that there are more people outside the pool, just waiting to jump in after some of the others leave. Those folks represent the potential acidity. When we determine how much lime we need to neutralize the acidity in the soil, it is really the potential acidity that needs to be accounted for. To neutralize the active acidity is easy and requires little lime, but the potential acidity can be a major problem to neutralize if it warrants such action.