Farming is about manipulating biomass transfer, so that as much of the energy captured by producers as possible ends up in food for humans.Increasing crop production (NPP)
• Removing weeds with herbicides reduces competition for light, water and minerals.
• Killing pests with pesticides (and fungicides) stops biomass being lost to other consumers.
• Adding fertilisers supplies minerals such as nitrate and phosphate.
• Irrigation supplies water; greenhouses can raise temperature, light and CO2 concentration.
• Selectively bred or genetically modified crops can have higher yields.Increasing the efficiency of livestock
• Keeping animals in warm, indoor pens restricts movement and reduces heat loss, so less energy is used in respiration and more goes into growth.
• Feeding high-protein, easily digested feed reduces losses in faeces.
• Slaughtering animals young, while they are still growing fast, improves the ratio of growth to respiration.
• Selective breeding produces faster-growing animals.Shortening the food chain
Every extra trophic level loses most of the biomass. Humans eating crops directly gain far more energy per hectare than humans eating animals fed on crops.Harvesting
Sustainable harvesting keeps a large enough population to regrow, for example by mowing grass for hay or by setting fishing quotas.These methods raise food output but can raise ethical and environmental issues, such as animal welfare in intensive farming, pesticide effects on non-target species, and eutrophication from fertiliser run-off.
• Removing weeds with herbicides reduces competition for light, water and minerals.
• Killing pests with pesticides (and fungicides) stops biomass being lost to other consumers.
• Adding fertilisers supplies minerals such as nitrate and phosphate.
• Irrigation supplies water; greenhouses can raise temperature, light and CO2 concentration.
• Selectively bred or genetically modified crops can have higher yields.Increasing the efficiency of livestock
• Keeping animals in warm, indoor pens restricts movement and reduces heat loss, so less energy is used in respiration and more goes into growth.
• Feeding high-protein, easily digested feed reduces losses in faeces.
• Slaughtering animals young, while they are still growing fast, improves the ratio of growth to respiration.
• Selective breeding produces faster-growing animals.Shortening the food chain
Every extra trophic level loses most of the biomass. Humans eating crops directly gain far more energy per hectare than humans eating animals fed on crops.Harvesting
Sustainable harvesting keeps a large enough population to regrow, for example by mowing grass for hay or by setting fishing quotas.These methods raise food output but can raise ethical and environmental issues, such as animal welfare in intensive farming, pesticide effects on non-target species, and eutrophication from fertiliser run-off.