The three steps of nitrogen nitrogen cycle in order, starting with nitrogen, gas in the atmosphere are
1. Nitrogen Fixation: Nitrogen gas in the atmosphere is converted into ammonium (NH4+) or nitrate (NO3-) ions by nitrogen-fixing bacteria. This process can also occur through lightning strikes.
2. Nitrification: The ammonium ions produced in the previous step are converted into nitrates (NO3-) by nitrifying bacteria. This conversion occurs in two steps: first, ammonium ions are oxidized to nitrites (NO2-) by nitrosomonas bacteria, and then nitrites are further oxidized to nitrates by nitrobacter bacteria.
3. Denitrification: Nitrates in the soil are converted back into nitrogen gas by denitrifying bacteria. This occurs under low-oxygen or anaerobic conditions, and the nitrogen gas is released back into the atmosphere, completing the nitrogen cycle.