pH

potential Hydrogen ions. Acidity or alkalinity of the soil is measured by pH. Basically it measures the amount of lime (calcium) contained in your soil. Acid soils are most common in moist climates, alkaline soils are most common in dry climates. A soil with a pH of 7 is considered neutral. A soil with a pH lower than 7.0 is considered acidic, a pH rating above 7 indicates alkalinity.