2.5.4

Fertilizers & Eutrophication

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Fertilisers

Fertilisers replace nutrients lost from the soil during harvesting and removing livestock to help maximise yields in agriculture.

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Agricultural impacts on soil

  • Agriculture leads to depleted levels of nutrients in the soil (e.g. nitrogen and phosphates).
  • This is because when crops are removed for harvest, they are not decomposed and the nutrients are not returned to the soil for reuse.
  • Removing livestock for slaughter also decreases nutrient levels because they are not replaced by decomposition.
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Using fertilisers

  • Fertilisers can be used to replace the nutrients (e.g nitrogen and phosphate) lost through agriculture.
  • Increasing nutrient levels by fertilisers allows farming to continue without negative impacts on the crop or livestock quality.

Eutrophication

Using fertilisers can have negative impacts on the environment. For example, eutrophication can happen when too much fertiliser is used. The process of eutrophication is:

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1) Leaching and overflow

  • Fertilisers that are sprayed onto fields can leach through the soil or flow into ponds, rivers and lakes.
    • Leaching is when water-soluble plant nutrients are lost from the soil.
  • This causes a build up of nutrients in the water.
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2) Algal overgrowth

  • The excess of nutrients cause algae to rapidly grow on the surface of the water.
  • As algae accumulate, light is prevented from reaching the plants in the water beneath.
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3) Plant death

  • The plants underneath the algae eventually die because there is insufficient light for them to photosynthesise.
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4) Increase in numbers of bacteria

  • Bacteria decompose the dead plants.
  • As numbers of bacteria increase, the oxygen concentration in the water decreases.
  • Fish and other organisms will now die because there is not enough oxygen.

Jump to other topics

1Physical Chemistry

1.1Atoms, Molecules & Stoichiometry

1.2Atomic Structure

1.3Chemical Bonding

1.4States of Matter

1.5Chemical Energetics

1.6Electrochemistry

1.7Equilibria

1.8Partition Coefficient

1.9Reaction Kinetics

2Inorganic Chemistry

3Organic Chemistry & Analysis

3.1Introduction to Organic Chemistry

3.2Hydrocarbons

3.3Halogen Derivatives

3.4Hydroxy Compounds

3.5Carbonyl Compounds

3.6Carboxylic Acids & Derivatives

3.7Nitrogen Compounds

3.8Polymerisation

3.9Analytical Techniques

3.10Organic Synthesis

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