Final answer:
The nitrogen cycle is the process by which nitrogen is recycled through the biosphere. It involves four main steps: nitrogen fixation, decay, nitrification, and denitrification.
Step-by-step explanation:
Nitrogen Cycle
The nitrogen cycle is the process by which nitrogen is recycled through the biosphere. It involves four main steps: nitrogen fixation, decay, nitrification, and denitrification. Nitrogen fixation is the process by which nitrogen gas is converted into forms that plants can use, such as nitrates. This is carried out by nitrogen-fixing bacteria. Decay is the breakdown of organic matter, which releases nitrogen back into the soil. Nitrification involves the conversion of ammonium ions into nitrates, which can be taken up by plants. Denitrification is the conversion of nitrates back into nitrogen gas by denitrifying bacteria.
The cycle includes several critical steps:
Nitrogen fixation - Conversion of nitrogen gas into ammonia (NH₃) or nitrate (NO₃⁻) by bacteria living in soil or in symbiosis with legumes.
Decay - Decomposers turn organic nitrogen into ammonium (NH₄⁺).
Nitrification - Nitrifying bacteria convert ammonium into nitrite (NO₂⁻) and then to nitrate.
Denitrification - Denitrifying bacteria change nitrates back into gaseous nitrogen, completing the cycle.
This continuous process ensures the availability of nitrogen in a form that plants can assimilate, thus supporting the ecosystem's productivity.