Plants produce their own energy using air, water and sunlight, but require fertile soil or growth media to provide essential nutrients. Healthy, well-fed plants are able to withstand environmental stress, diseases and insect pressure. For a small investment, routine soil analysis can establish your soil's fertility level and determine if any corrective measures are required. Soil testing is the most effective tool available for determining lime and fertilizer needs to produce healthy plants and protect the environment. Soil testing removes the guesswork and prevents the risk of over or under fertilizing.