Soil analysis should be considered an essential tool in establishing a new orchard. Practical adjustments in soil pH, P, K, and Mg can best be made before trees are planted. Soil analysis in established orchards has some limitations and research has shown that results may correlate poorly with leaf-tissue analysis and tree responses. Nonetheless, a good soil sample can reveal much about the relative levels of Ca, P, K, and Mg in the soil as well as the need for lime. The greatest value in sampling soil in established orchards lies in the pH determination and the lime requirement.
Soil acidity has a significant impact on the availability of nutrients.
A good example in the mid-Atlantic region is Ca. Many of the soils in this region have very high Ca levels but soil pH levels of 5.0 to 5.5. Under these conditions Ca availability to the tree is significantly limited. It is recommended that soil analysis be conducted at least once every three years. In blocks with previous problems, such as low pH, a soil analysis every year or two may be advised, at least until the problem is corrected.