pollution

• pesticides


  • pesticides are deliberately used because they are toxic and are intended to kill pests
  • because pesticides are not species-specific, sensitive non-target species may also be killed
  • species may also be affected if inter-species relationships are affected such as the death of food species, pollinators, or pollution that favours competitor species
• nutrient pollution

  • the nutrients that were intended to stimulate crop growth, or are digestive wastes from livestock, can stimulate the growth of undesirable organisms
  • leached inorganic nutrients cause eutrophication, for example, nitrate fertiliser
  • organic nutrients such as manure can cause deoxygenation of rivers and lakes because of the aerobic respiration of bacteria
• nitrate toxicity

  • nitrates can be leached from farmland into water bodies that are used as sources of potable water for human consumption
  • high nitrate levels can cause blue baby syndrome and nitrates may be a human carcinogen
• climate change

  • several farming activities release greenhouse gases
  • carbon dioxide - fossil fuel use, ploughing increases soil aerobic respiration
  • methane - microbial anaerobic digestion: livestock intestines, rice padi fields
  • oxides of nitrogen (nitrous oxide) - from livestock manure and nitrogen fertilisers
• embodied energy


  • the manufacture of materials, especially nitrate fertilisers, and machinery, usually involves the use of fossil fuels and causes the release of GHGs, mainly carbon dioxide