Nitrogen cycle
Nitrogen is transferred between living organisms and their environment.
Image caption, Decomposition
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Bacteria carry out the following processes in the nitrogen cycle:
Nitrogen fixation
- Nitrogen gas is converted into The chemical absorbed from the soil by plants to produce their protein..
- This is carried out by nitrogen fixing bacteria.
- Nitrogen fixing bacteria need oxygen as they are Respiration in the presence of oxygen..
- This process is quickened by the presence of oxygen and higher temperatures.
- These bacteria can be found ‘free’ in the soil or in Swellings found on roots. found on the roots of plants such as peas, beans, and clover.
- Within the Swellings found on roots. the bacteria gain carbohydrates from the plant and the plant gains a source of nitrates in return
Decomposition
- Bacteria/fungi break down protein found in dead plants and animals, urine and Waste matter from the bowels. into ammonia.
Nitrification
- Ammonia is converted into nitrates.
- This is carried out by nitrifying bacteria.
- Nitrifying bacteria needs oxygen as they are aerobic.
- This process is quickened by the presence of oxygen and higher temperatures.
Denitrification
- Nitrates are converted into nitrogen gas.
- This process is disadvantageous for the soil and plants.
- This is carried out by denitrifying bacteria.
- Denitrifying bacteria do not need oxygen as they are Respiration in the absence of oxygen. (therefore they thrive in waterlogged soil).
