What does a low pH number indicate?

A low pH number indicates acidity. The pH scale ranges from 0 to 14, with values below 7 indicating acidic conditions. The lower the pH number, the more acidic the solution is. For example, a pH of 1 is highly acidic, while a pH of 6 is considered slightly acidic. Understanding the pH level is critical in various applications, including agriculture and horticulture, as it influences nutrient availability and the health of plants.

In contrast, a pH of 7 is classified as neutral, and values above 7 indicate alkalinity. Fertility, while important in the context of soil and plant health, is not directly indicated by the pH level. Therefore, low pH numbers are directly associated with acidity, making this the correct answer.