Human Influence: Farming, Farming Pollution, Striking a Balance
Edited by Jamie (ScienceAid Editor), Taylor (ScienceAid Editor)
The human population is increasing by more and more each year (estimated to be over 7 billion at present). The majority of resources on earth are used for the single species: Homo sapiens. In order to feed the billions of people, far more intensive methods of farming have been used. Every year the efficiency of crop production increases because of progress in crop science, these increases however aren't keeping up with the population increases.
Traditionally farms had a variety of crops and animals. The modern farm specializes in one type of crop: a monoculture. This makes the farmers money, but because exactly the same species inhabits large areas, nutrients are depleted quickly; so industrial fertilizers have to be used. Traditionally a field would have been rotated so that, over several years, it grows a variety of crops, and the soil is naturally fertilized.
Another issue in farming concern hedgerows. These have been removed to provide more space for farming and prevents pests, for example, but on the other hand, this increases erosion by wind when crops haven't grown strong enough yet, and removes an important ecosystem for birds and rodents.
Farming produces huge amounts of waste, both from inorganic sources such as fertilizers and organic sources such as cattle effluent. Generally, effluent is well managed, but when it seeps in to bodies of water, the nitrates and phosphates can cause eutrophication.
- 1To begin with, large amounts of mineral and certain favourable conditions can cause an algal bloom, where the phytoplankton population leaps. This blocks light to aquatic plants so they can't photosynthesize and so they die. These decay at the bottom of the water and large amounts of aerobic bacteria feed on them - using up the oxygen. This lack of oxygen in the water means that fish will die.Algai Bloom.Advertisement
- 2The effects of eutrophication are monitored by the authorities. They keep track of the biochemical oxygen demand. This is measured by collecting water samples and measuring the oxygen concentration before and after it is incubated. The difference gives an indication of the aerobic bacteria in the water.Eutrophication.
- 4This is the increase in pesticide as you move up a food chain. If the organism at the bottom has small amounts of pesticide, the predator that eats 100 of these will get 100 times the amount of pesticide than were in the original organisms. The same will happen to the next predator so that the final consumer (often humans) will have huge amounts of pesticide.Biomagnification (see diagram above).
- 5A way of preventing bioaccumulation and biomagnification is to have pesticides that degrade and so they will not get stored in organisms. Modern pesticides are tested extensively and these rarely tend to be a problem, although there is always a chance of some slipping through the net.Pesticides.
- Loss of Biodiversity. Upsetting biodiversity is one of the side effects of using pesticides. If you have something to kill insects that might eat your crops, it is also likely to have an affect on other insects in the environment. So pesticides must be developed to take this in to account.
- Extensive use of a pesticide can lead to the rapid development of resistance to it. If 1 in 100 insects are resistant to an insecticide and this is sprayed it will kill the 99 in 100 that are affected, but now the entire population will be founded by individuals that have resistance and soon the insecticide is useless. I way of addressing this is to have a refuge near the crop where the pest can live without any selection for resistance.
Reaching a Balance
Although modern farming has many negative impacts, reverting to traditional and less harmful methods would not provide enough for our ever expanding population, so we need to strike a balance between meeting the demand for food and conserving the environment. In Europe, farmers generate surplus crops as a result of more efficient practises, so they can now afford to become more sustainable. With the encouragement of governments, some of the following are being done to improve sustainability.
|Organic Fertiizer||Retains more water. When it decays, nutrients are slowly released so they are less likely to be washed away.|
|Soil Erosion||Leaving crop stubble over winter protects the soil; building furrows on slopes stops water running down them quickly and washing away topsoil.|
|Set aside||This is leaving areas of land to develop naturally. In order to receive subsidies, European farmers must set aside around 10% of their land.|
|Hedgerows||Maintaining and developing hedgerows improves biodiversity.|
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Categories : Ecology
Recent edits by: Jamie (ScienceAid Editor)