The Nitrogen Cycle and Microorganisms
Biology: Edexcel IGCSE, topic 5.1.21
The Nitrogen Cycle and Microorganisms
The cycle of nitrogen through the ecosystem relies on microorganisms at many stages:

Decomposition
- Microorganisms break down decaying matter and return nitrogenous compounds to the soil.
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Nitrification
- Nitrifying bacteria convert ammonium into nitrates.

Nitrogen fixation
- Bacteria in plants' root nodules 'fix' nitrogen into a useable form for plants.
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Denitrification
- Denitrifying bacteria remove nitrogenous compounds from the soil and release nitrogen back into the air.
Test yourself on The Nitrogen Cycle and Microorganisms
In which of the following stages of the nitrogen cycle are microorganisms NOT relied upon?