Energy and Food Production

Natural fertilisers (i.e organic - manure) 

• cheaper - economic to use as it's using waste materials.
• may improve soil structure
• ion content unknown and cannot be controlled
• animal manures may contain disease which could be harmful to plants

Artificial fertilisers (i.e inorganic - pure chemicals)

• expensive - value of increased yield must exceed the cost of buying and applying fertiliser
• can require the use of heavy machinery
• if used excessively may lead to leaching - eutrophication.
• may change balance of nutrients in soil causing harm to other organisms. 

Controlling conditions organisms live in.

• warm sheltered environment - less energy is lost by heat
• tightly packed and in cramped conditions to prevent movement - less energy lost through respiration/movement.
• fed on controlled diet high in certain nutrients to increase absorption
• slaughtered when still growing so more energy is converted to biomass
• genetically selected for high productivity