Fertilisers

• Nitrogen is important because it is needed to make proteins and DNA.
• Plants can absorb nitrogen (in the form of nitrates in the soil) through their roots.
• Animals eat plants or other animals to digest the plant/animals protein and use the amino acids to make more protein.
• Plants need a lot of nitrogen and the nitrates in the soil may run out of crops keep being grown on the same piece of land.
• Farmers can use fertilisers to replace a loss in nitrates.
• The first stage of eutrophication is fertiliser leaches into lakes/rivers due to rain or excess watering.
• The second stage of eutrophication is an algal bloom forms and covers the surface of the water due to being fertilised and this blocks the sunlight.
• The third Stage of eutrophication is aquatic plants can not photosynthesise so they die due to lack of sunlight.
• The fourth stage of eutrophication is dead plant material being used as food for bacteria.
• The fifth stage of eutrophication is where bacteria increase in number and use up the oxygen.
• The sixth stage of eutrophication is aquatic animals dying due to lack of oxygen.
• When pesticides are sprayed onto crops they can accumulate in the bodies of organisms over time. As they are passed along food chains toxicity increases and can reach lethal levels.
• The build up of pesticides in living organisms is known as bioaccumulation.
• Alternatives to pesticides include Genetically modified crops which are resistent to pests or biological control by in trouncing a natural enemy to control the pests. Like a predator or parasite.