List the 3 steps of the nitrogen cycle, starting with nitrogen gas in the atmosphere.
1. Nitrogen Fixation: Nitrogen gas in the atmosphere is converted into a form that can be used by plants, typically by nitrogen-fixing bacteria found in the soil or in the roots of certain plants.
2. Nitrification: Ammonia (NH3) produced from nitrogen fixation is converted into nitrites (NO2-) and then nitrates (NO3-) by nitrifying bacteria in the soil.
3. Denitrification: Nitrates in the soil are converted back into nitrogen gas by denitrifying bacteria, completing the cycle by releasing nitrogen back into the atmosphere.