One measurement we use in helping to determine overall soil health is soil pH. This is a common concept and important to understand, but is only one of many measurements we use to determine overall soil health. A good soil health recommendation will take many factors into consideration, but soil pH is the starting point, as it helps us determine nutrient availability, the tightness of soils, and the ability of soil biology to thrive or not. The wrong pH may encourage fungal pathogens, while the proper soil pH range will encourage good soil microbes.
The pH scale runs from 0 to 14. Any pH reading below 7 is acidic and any pH above 7 is alkaline. A pH of 7 indicates a neutral soil. Most trees will grow in soils having a pH between 6.5 (slightly acid) and 7.2 (slightly alkaline). Ideally, maintaining a soil close to 6.8 is perfect for most trees. There are a few plants that prefer a soil pH below 6.0. These “acid-loving” plants include azaleas, rhododendrons, and blueberries. The soil pH for these plants can be lowered by incorporating elemental sulfur (S) into the soil. Since the soil acidifying response to elemental sulfur is slow, it should be applied and incorporated a year before planting.