21.1) Food supply
Modern technology has resulted in increased food production:
- Agricultural machinery is used to clear the land, prepare the soil and plant, maintain and harvest crops to improve efficiency.
- Chemical fertilisers are used to provide minerals to increase the yield of crops.
- Pesticide is a chemical that destroys agricultural pests or competitors:
- Herbicides are chemicals that kills plants that compete with the crop plant for root space, soil minerals and sunlight.
- Insecticides are chemicals that destroy the insects that eat the damage the plants.
- Selective breeding to improve production by crop plants and livestock, eg. cattle, fish and poultry.
The negative impact of monocultures:
- The whole point of crop farming is to remove a mixed population of trees, shrubs, wildflowers and grasses and replace it with a dense population of only one species such as wheat or beans.
- Monoculture: when a crop of a single species is grown on the same land, year after year.
- In a monoculture, every attempt is made to destroy organisms that feed on, compete with or infect the crop plant.
- So, the balanced life of a natural plant and animal community is displaced from farmland and left to survive only in small areas of woodland, health or hedgerow.
The negative impact of livestock production:
- Intensive livestock production is also known as ‘factory farming’.
- Chickens and calves are often reared in large sheds instead of in open fields.
- Their urine and faeces are washed out of the sheds with water forming ‘slurry’.
- If this slurry gets into streams and rivers it supplies an excess of nitrates and phosphates for the microscopic algae.
- This starts a chain of events, which can lead to eutrophication of the water system.
- Overgrazing can result if too many animals are kept in a pasture.
- They eat the grass down almost to the roots, and their hooves trample the surface soil into a hard layer.
- As a result, the rainwater will not penetrate the soil so it runs off the surface, carrying the soil with it.
- The soil becomes eroded.
The problems of world food supplies:
- There is not always enough food available in a country to feed the people living there.
- A severe food shortage can lead to famine.
- Food may have to be brought in (imported).
- The redistribution of food from first world countries to a poorer one can have a detrimental effect on that country’s local economy by reducing the value of food grown by local farmers.
- Some food grown by countries with large debts may be exported as cash crops, even though the local people desperately need the food.
Problems which contribute to famine:
- Climate change and natural disasters such as flooding or drought; waterlogged soil can become infertile due to the activities of denitrifying bacteria, which break down nitrates.
- Shortage of water through its use for other purposes, the diversion of rivers, building dams to provide hydroelectricity.
- Eating next year’s seeds through desperation for food.
- Poor soil, lack or inorganic ions of fertiliser.
- Desertification due to soil erosion as a result of deforestation.
- Lack of money to buy seeds, fertilizers, pesticides or machinery.
- War, which can make it too dangerous to farm, or which removes labour.
- Urbanisation (building on farmland); the development of towns and cities makes less and less land available for farmland.
- An increasing population.
- Pest damage or disease.
- Poor education of farmers and outmoded farming practices.
- The destruction of forests, so there is nothing to hunt and no food to collect.
- Use of farmland to grow cash crops, or plants for biofuel.