Which of the following is NOT a reason for the soil to become acidic?

The assertion that coal burning is not a reason for soil to become acidic is accurate because coal burning primarily contributes to environmental issues like air pollution and acid rain, but it doesn’t directly acidify the soil itself.

In contrast, rainfall can lead to soil acidity, especially in areas where the precipitation leaches away basic cations like calcium and magnesium. This process can leave behind more acidic ions. Nitrogen fertilizers often contribute to soil acidification as they can increase the availability of ammonium, which when nitrified can release hydrogen ions into the soil, lowering pH. Additionally, carbon dioxide (CO2) from root activity contributes to soil acidity through the formation of carbonic acid as CO2 dissolves in soil moisture, further decreasing soil pH.

Thus, when considering the factors that cause soil to become acidic, coal burning stands out as not directly influencing soil acidity in the same way that the other three options do.