How do other bacteria reduce the availibility of nitrate ions to plants???
Answers
Answer:
Nitrogen compounds found in cells include proteins. Nitrogen from the air is converted into soluble ions that plant roots can absorb. It forms part of nitrogen compounds in the plants, and is then passed from one organismto the next. It is returned to the atmosphere as nitrogen gas. This is the nitrogen cycle.
The slideshow shows how the cycle works.
Stage one of the nitrogen cycle
Stage one - fixation
About 78 per cent of the air is nitrogen gas. However, nitrogen is too unreactive to be used directly by plants to make protein. It must be converted into soluble ions, such as nitrates. Nitrogen-fixing bacteria in root nodules are able to do this. Lightning can also convert nitrogen gas into nitrates.
Plant growing in soil with roots magnified to show the root nodules containing nitrogen-fixing bacteria
Legumes such as bean and clover have root nodules containing nitrogen-fixing bacteria
The Haber process converts nitrogen gas into ammonia for use in fertilisers. Nitrifying bacteria in the soil can convert ammonium ions into nitrates.
Stage two - absorption into roots and incorporation into plants
Plants absorb nitrates from the soil and use these to make proteins.
Stage three - moving along food chains and excretion
When an animal eats a plant, nitrogen from the plant’s proteins becomes proteins in the animal. Nitrogen is also passed from one animal to another by feeding.
Stage four - death of animals
Decomposers break down urea, egested material (eg faeces) and dead bodies. This results in nitrogen being returned to the soil as ammonium ions, which nitrifying bacteria can convert into nitrates for plants to absorb.
Stage five - release into atmosphere
Denitrifying bacteria in the soil break down nitrates and return nitrogen gas to the air.
Explanation: