What does soil pH measure?

Soil pH specifically measures the concentration of hydrogen ions (H+) in the soil solution. This is crucial because the pH level affects various chemical reactions in the soil, influencing nutrient availability and mobility. For instance, a lower pH (more acidic) indicates a higher concentration of hydrogen ions, which can lead to the leaching of basic nutrients and make certain nutrients, like aluminum, more available in toxic forms to plants. Conversely, higher pH levels (more alkaline) can reduce the availability of micronutrients such as iron and zinc.

Understanding soil pH is vital for effective nutrient management in agriculture. It helps in determining how to amend soil to optimize nutrient availability for crops. It also plays a role in soil microbial activity and organic matter decomposition. Hence, measuring the concentration of hydrogen ions gives a direct indication of the soil's acidity or alkalinity, which is fundamental for maintaining soil health and fertility.