In the nitrogen cycle, which reaction leads to the release of nitrogen back into the atmosphere?

In the nitrogen cycle, denitrification is the process that leads to the release of nitrogen back into the atmosphere. During denitrification, microorganisms convert nitrate (NO3-) and nitrite (NO2-) in the soil into nitrogen gas (N2) or, to a lesser extent, nitrous oxide (N2O), which are both gaseous forms of nitrogen. This process occurs in anaerobic conditions, typically in waterlogged or poorly draining soils where oxygen levels are low.

As denitrification progresses, nitrogen, a vital component of the atmosphere, is returned to its gaseous state, completing its cycle and contributing to the balance of atmospheric nitrogen. This process is crucial for maintaining the nitrogen cycle, as it prevents the accumulation of nitrates in the ecosystem, which can lead to issues such as water pollution and eutrophication.

On the contrary, mineralization involves the transformation of organic nitrogen from decomposed materials back into inorganic forms, which are typically then utilized by plants. Immobilization is the process whereby inorganic nitrogen is converted into organic forms, making it temporarily unavailable for plants and microorganisms. Nitrification involves the conversion of ammonium (NH4+) to nitrate (NO3-) via intermediate forms, which again does not release