What causes soil acidity?

Soil acidity primarily results from the concentration of hydrogen ions (H+). When the concentration of these ions increases, the pH of the soil decreases, leading to higher acidity levels. This process can occur due to various natural and anthropogenic factors, including the decomposition of organic matter, microbial activity, and precipitation processes that release H+ ions into the soil.

Other factors, such as organic matter, nitrogen uptake, and temperature, may influence soil properties but do not directly cause acidity in the same way that H+ ion concentration does. For instance, while high levels of organic matter can contribute to soil health and influence nutrient availability, they are not the primary drivers of soil acidity. Similarly, excessive nitrogen uptake can affect soil nutrient dynamics but does not solely determine the acidity. Low soil temperatures can impact microbial activity and organic matter breakdown rates but do not directly generate or increase soil acidity. Thus, the concentration of hydrogen ions stands out as the principal cause of soil acidity.