What does soil pH measure?

Soil pH specifically measures the acidity or alkalinity of the soil, which is determined by the concentration of hydrogen ions present. This measurement is crucial for understanding the availability of nutrients to plants, as different pH levels can affect the chemical behavior of nutrients in the soil. For example, many nutrients are most available to plants when the soil pH is around 6 to 7, which is considered neutral to slightly acidic. If the soil is too acidic (low pH) or too alkaline (high pH), it can lead to nutrient deficiencies or toxicities that adversely affect plant growth.

In contrast, the other options do not pertain to the measurement of pH: soil temperature relates to heat levels in the soil, soil moisture content measures the amount of water present, and soil organic matter refers to the decomposed materials in the soil, none of which are directly related to the acidity or alkalinity measured by pH.