What is the process called when nitrogen is lost from the soil to the atmosphere?

The process when nitrogen is lost from the soil to the atmosphere is known as denitrification. During denitrification, nitrogen compounds present in the soil are converted by various bacteria into nitrogen gas (N2) or, to a lesser extent, nitrous oxide (N2O), which are then released back into the atmosphere. This process primarily occurs in anaerobic conditions, such as waterlogged soils, where bacteria utilize nitrate (NO3-) or nitrite (NO2-) as an alternative to oxygen for respiration.

Understanding denitrification is crucial in the context of nutrient cycling and soil fertility, as it can lead to the depletion of nitrogen in the soil which is essential for plant growth.

In contrast, nitrification refers to the conversion of ammonia into nitrate compounds, while mineralization is the process of organic nitrogen being converted into inorganic forms, and fixation involves the conversion of atmospheric nitrogen into forms that are usable by plants and other organisms.