Back to the air

The idea

Denitrifying bacteria such as Pseudomonas convert some nitrates back into nitrogen gas, completing the cycle and keeping nitrogen balanced in ecosystems.

Where does nitrate go?

Nitrate in the soil can be used by plants. But some of it is turned back into a gas.

Which gas do you think it becomes?

• Nitrogen gas
• Oxygen
• Carbon dioxide

Complete the loop

Press Next step.

The loop is closed

Nitrate does not pile up for ever. Some of it goes back to the air as nitrogen gas, which closes the cycle.

Denitrifying bacteria such as Pseudomonas convert some nitrates back into nitrogen gas, completing the cycle and keeping nitrogen balanced in ecosystems.

Notes

Denitrifying bacteria such as Pseudomonas convert some nitrates back into nitrogen gas, completing the cycle and keeping nitrogen balanced.

Check yourself

Which kind of bacteria convert some nitrates back into nitrogen gas?

What is the gas formed when nitrates are converted back?

What is the process of converting nitrates back into nitrogen gas called?

What does denitrification do for the nitrogen cycle?

• Nitrifying bacteria such as Nitrobacter. Nitrobacter converts nitrite into nitrate.
• Nitrogen-fixing bacteria such as Rhizobium. Nitrogen-fixing bacteria convert N₂ into ammonia, the opposite direction.
• Denitrifying bacteria such as Pseudomonas — correct. Yes!
• Nitrogen gas (N₂) — correct. Yes!
• Ammonia (NH₃). Ammonia is formed from N₂ by nitrogen-fixing bacteria.
• Oxygen (O₂). Denitrifying bacteria convert nitrates back into nitrogen gas.
• Nitrification. Nitrification converts ammonia into nitrite and then nitrate.
• Denitrification — correct. Yes!
• Ammonification. Ammonification is the return of ammonia to the soil by decomposers.
• Stops the cycle. Denitrification completes the cycle.
• Adds more ammonia to the air. Denitrification converts some nitrates back into nitrogen gas.
• Completes the cycle and maintains a balance of nitrogen in ecosystems — correct. Yes!