Nutrient Cycle Flashcards
What is nitrogen fixation?
When nitrogen gas is reduced to ammonia by bacteria called rhizobium
Where can nitrogen fixating bacteria be found?
Inside root nodules of leguminous plants
What are the stages of the nitrogen cycle ?
- Nitrogen fixation
- Feeding
- Decomposition
- Ammonification
- Nitrification / denitrification
Describe the process of nitrogen fixation.
Nitrogen fixing bacteria convert nitrogen into ammonia - forms ammonium ions which plants can use.
Describe the process of ammonification.
Nitrogen compounds from dead organisms/waste products are converted to ammonia by Saprobionts
What is nitrification ?
Ammonium ions in the soil are oxidised to nitrites and nitrates by nitrifying bacteria.
What is denitrification?
Nitrates in the soil are converted to nitrogen gas by denitrifying bacteria (anaerobic conditions e.g. waterlogged soil)
Other than the nitrogen cycle, how can nitrogen get into ecosystems?
- Lightning (forms nitrogen oxides from nitrogen)
- Artificial fertilisers (Haber process)
Why are plants unable to use the nitrogen straight from the air?
Nitrogen gas is unreactive and is not easily converted into other compounds.
What do microbial saprophytes do?
The break down proteins in detritus to form ammonium ions (ammonification or deamination).
