What does nitrification refer to?

Nitrification is the biological process that specifically describes the conversion of ammonium (NH4+) into nitrate (NO3-). This two-step process involves the oxidation of ammonium to nitrite (NO2-) by ammonia-oxidizing bacteria and then the further oxidation of nitrite to nitrate by nitrite-oxidizing bacteria. Nitrate is a form of nitrogen that plants readily absorb and utilize for growth.

The importance of nitrification in nutrient management lies in its role within the nitrogen cycle, which is essential for maintaining soil fertility and supporting agricultural productivity. Understanding this process allows farmers and agricultural managers to optimize nitrogen use, mitigate potential environmental impacts, and improve crop nutrition.

While the other options involve nitrogen in various forms or processes, they pertain to different aspects of the nitrogen cycle or nitrogen transformations that do not fit the specific definition of nitrification. For instance, converting organic nitrogen into inorganic nitrogen relates more to mineralization, while denitrification pertains to the loss of nitrogen, which is not what nitrification signifies. Fixation of atmospheric nitrogen refers to the process of converting atmospheric nitrogen into a usable form for plants, which is also outside the scope of nitrification.