Nitrogen Cycle

Nitrogen Fixation

The process of converting atmospheric nitrogen into ammonia and nitrates.

Ammonification

The production of ammonia by bacteria during the decay of nitrogen-containing organic matter.

How do animals contribute to ammonification?

Animals excrete and eliminate nitrogen in urine and feces, which soil bacteria convert into ammonia.

What role do soil bacteria play in ammonification?

Soil bacteria convert nitrogen compounds in dead plants and animals to ammonia.

How do plants utilize ammonia produced during ammonification?

Some of this ammonia is absorbed by plants and used to make protein and nucleic acids.

Nitrification

The production of nitrates from ammonia by several different bacteria in the soil.

What happens to nitrates produced during nitrification?

Nitrates are absorbed by the plants.

Denitrification

The conversion of nitrate to nitrogen gas by bacteria.

What is the role of bacteria in denitrification?

Another kind of bacteria converts remaining nitrate back into nitrogen gas, which is released into the atmosphere.