Which nitrogen fertilizer is known for its acidification potential?

Ammonium nitrate is recognized for its acidification potential primarily due to the nitrogen forms it contains. When ammonium nitrate is applied to the soil, the ammonium (NH4+) component can be converted to nitrate (NO3-) through microbial processes, a process known as nitrification. This transformation releases hydrogen ions (H+) into the soil, which can lower the pH and contribute to soil acidification over time. This acidifying effect is particularly significant in certain environments and cropping systems, where maintaining soil pH at optimal levels is crucial for crop health and nutrient availability.

In contrast, urea and sodium nitrate do not have the same acidification potential. Urea requires hydrolysis to convert to ammonium, which does not directly release hydrogen ions in the same way. Calcium nitrate, while it can contribute to nutrient supply, also has components that can mitigate acidification because it adds calcium, which can help to counteract soil acidity. Therefore, ammonium nitrate stands out as the nitrogen fertilizer with a notable potential to acidify soils due to its specific nitrogen chemistry and the related biological processes that occur once it is applied.