Fertilisers
When crops are To gather a crop. and animals are slaughtered the nutrients they took from the soil are lost.
In order to replace these lost nutrients, farmers use natural (e.g. Animal dung and excrement that can be used as a fertiliser., Animal dung (solid waste) used as fertiliser. and Decayed organic matter which can be used as a plant fertiliser.) or artificial fertiliser.
Fertilisers mainly contain nitrates that the crops can use for growth. They can also contain calcium, needed for the production of plant cell walls and magnesium, which is needed to make The green chemical inside the chloroplasts of plant cells. It enables photosynthesis to take place..
If nutrients are removed but not replaced the soil will eventually lose its ability to grow crops.
Eutrophication
Eutrophication is a type of water pollution caused by the addition of sewage or fertiliser.
The sewage or fertiliser run-off increases the nitrate concentration of the water and has a negative effect on the aquatic A community of animals, plants and microorganisms, together with the habitat where they live..
Process
- Sewage or fertiliser run-off increases the nutrient concentration of the water.
- Extra nutrients cause increased growth of the aquatic plants/algae â this is known as an algal bloom.
- The algal bloom covers the waterâs surface killing any plants below the surface as light and oxygen cannot reach them.
- Algae also die as the nutrients run out.
- With oxygen. bacteria decompose the dead plants.
- Bacteria use up oxygen for Chemical reaction that takes place inside living cells, which uses glucose and oxygen to release the energy organisms need to live. Carbon dioxide and water are by-products of respiration..
- Fish and other organisms die from a lack of oxygen.
Controlling the use of fertiliser and storing manure and slurry more securely can reduce eutrophication.