The three steps of the nitrogen cycle in order starting with nitrogen gas in the atmosphere are?
1. Nitrogen Fixation: Nitrogen gas (N2) in the atmosphere is converted into a usable form by nitrogen-fixing bacteria or through industrial processes such as the Haber-Bosch process. These bacteria have the ability to convert N2 into ammonia (NH3) or nitrate (NO3-), which can be used by plants.
2. Nitrification: Ammonia (NH3) produced through nitrogen fixation or from decomposing organic matter is converted into nitrite (NO2-) by nitrifying bacteria. Then, nitrite is further oxidized into nitrate (NO3-) by another group of nitrifying bacteria. Nitrate is the main form of nitrogen that can be absorbed and utilized by plants.
3. Denitrification: Denitrifying bacteria convert nitrate (NO3-) back into nitrogen gas (N2), completing the nitrogen cycle. This process occurs in anaerobic conditions, where oxygen is limited or absent, such as in waterlogged soils or deep in the ocean. Denitrification releases nitrogen gas back into the atmosphere, closing the cycle.