Biol 4 Farming

Intensive Farming Systems are more Productive than Natural Ecosystems

• A Natural Ecosystem ia an ecosystem that hasnt been changes by human activity.
• The energy input of a natural ecosystem is the amount of sunlight captured by the producers.
• Intensive farming involves changing an ecosystem by controlling the biotic or abiotic conditions to make it more favourable for the crops or livestock.
• This means that intensively farmed crops or livestock can have greater net productivity (a greater amount of biomass) than organisms in a natural ecosystem.
• The energy input might be greater in an intensively farmed area than in a natural ecosystem, for example cattle may be given food that's higher in energy than their natural food. However it might be the same as a natural ecosystem, for example a field of crops receives the same amount of light as a natural field.

Intensive Farming methods increase productivity in different ways

• They can increase the efficiency of energy conversion - more of the energy organisms have is used for growth and less is used for other activities, e.g. movement.
• They can remove growth imiting factors - more of the energy available is used for growth.
• They can increase the energy input - more energy is added to the ecosystem so there's more energy for growth.

The three main intensive farming practices are:

• Killing Pest Species
• Using Fertilisers
• Rearing Livestock Intensively

Killing Pest Species

• Pests are organisms that reduce the productivity of crops by reducing the amount of energy available for growth. this means that the crops are less efficient at converting energy.
• The 3 main ways that farmers reduce pest numbers are:
  • chemical pesticides
  • biological agaens
  • integrated systems
• chemical pesticides can directly and indirectly affect non-target species.
  • they can also be very expensive so it may not be profitable for the farmer.
• biological agaents may become a pest themselves
  • can move to another food source and kill other species
  • not short terms solutions as they wont work right away
• integrated systems use both so can be more effective than just using one.
  • can reduce environmental impact and cost.

Using Fertilisers

These are chemicals that provide crops with minerals needed for growth. Crops use up minerals in the soil as they grow, so their growth is limited when there aren't enough minerals. Adding fertilisers replace the lost minerals, so more energy from the ecosystem can be used to grow, increasing the eficiency of energy conversion.

• natural fertilsers are organic matter - manure, sewage, etc
• artificial fertilsers are inorganic - contain pure chemicals, e.g. ammonium nitrate
• using fertilisers raises environmental issues
  • fertiliser can be washed into rivers, killing fish and plant life by eutrophication
  • using fertilsers can change the balance of nutrients in the soil. too much of a particular nutrient can cause crops and other plants to die.
• there are also econmic issues:
  • use too much and money is wasted
  • too little and productivity is not increased so money is wasted.

Rearing Livestock Intensively

this involves controlling the conditions in which they live, so more of the energy is used for growth and less is used for other activites - the efficiency of energy conversion is increased so more biomass is produced and productivity is increased.

• animals my be kept in warm, indoor pens where their movement is restricted. less energy is wasted keeping warm and moving round.
• Animals may be given feed that's higher in energy than their natural food. this increases the energy input, so more energy is available for growth.

the benefits are that more food can be produced in a shorter space of time, often at a lower cost. however enhancing productivity by intensive rearing raises ethical issues. for example some people think that the conditions that intensively reared animals are kept in cause the animals pain, distress and restricts their natural behaviour, so it shouldn't be done.