Agricultural exploitation and human effects on the environment

Humans rely on earth's resources for a high quality of life. As the population surge continues, more food has to be produced to meet the high demands of people. However in relying on more and more resources, the population have forgotten to stop and think about the environment. The growth in human population has caused: * More waste is being produced. * More pollution is being caused. * Non-renewable energy resources, such as coal, oil and natural gas, are being used up rapidly. * Raw materials are being used up rapidly. Agricultural production has been rising over the last few decades. Production has been rising due to an increase in the development of various crops and animals, and more intensive methods of farming. New varieties if crops and farm animals have been developed by artificial selection and genetic engineering. Crops can be genetically engineered to be resistant to pests. Many foods now contain genetically modified organisms. Some humans think that these will help food production and maintain high standards of living for the population. However, there are people that believe that we have the ability to produce adequate food without genetically modified organisms. They believe that the genetically modified organisms should be researched into for long term effects on health and environment. Agriculture is becoming more and more mechanised and the conditions can be controlled much more than before. On many arable farms machines have replaced labourers almost entirely. Every stage of crop production is carried out by machines. Large amounts of pesticides are used to increase crop yield by reducing competition from weeds and minimizing losses to disease and pests. Inorganic and organic fertilisers keep mineral levels high in the soil. Without fertilisers, heavy harvesting, of most crops would deplete the soil of the minerals. A deficiency of any one mineral limits plant growth. Fertilisers can increase crop yields however above a particular level, the increase in crop yield for each unit of fertiliser used gets less. Worse to that is that if a high over use of fertiliser is used then it will result in a decrease in crop yield and also have the long lasting effect on the environment. Among the most intensive forms of farming are greenhouse cultivation of plants and factory farming of animals. Both these methods grow organisms indoor in a confined space under controlled environmental conditions. Growing plants in greenhouses allows conditions such as light intensity, temperature, carbon dioxide concentrations, and mineral levels to be controlled artificially. Many people are against factory farming due to the following reasons: * Intensive cultivation is not cost effective because it relies on the heavy use of fossil fuels * Antiobioitcs, pesticides, and growth-promoting substances may harm human health and the environment. * Excessive use of antibioticvs in farm animals is contributing to the evolution of antibiotic resistance * Intensive cultivation isn't cost effective and is damaging to the environment whereas organic farming isn't dependent on fossil fuels and is better for the environment. Land clearance for cultivation and for grazing reduces the number of habitats available. Tropical forests are cleared for timber and land use on a massive scale, destroying important habitats and making the soil unstable. Destruction of a habitat reduces variation and the gene pool. Maximum use is made of available agricultural land by intensive cultivation, including the use of nitrate fertilisers. This causes there to be soil erosion and eutrophication. Agricultural pests cause economic damage to crops and farm animals. They can have a terrible effect especially in monocultures in which only one crop is grown. These systems are simpler than natural ecosystems and usually lack the predators of pests. Also, the growing the same crop on the same land again and again may allow the pests to increase in number. Pests attack crop plants and animals – which reduces yield. They cause disease, spoil stored food, compete for resources and increase the chance of pathogenic disease. These factors have a bad effect leading to a reduced amount of food produced and a huge economic loss for farmers. à ¯Ã‚ ¿Ã‚ ½ Pests for plants include weeds, insects and crop diseases à ¯Ã‚ ¿Ã‚ ½ Weeds compete with crops for water, light and ions, – reducing crop yields à ¯Ã‚ ¿Ã‚ ½ Insects damage crops – By eating leaves – photosynthesis – Tunnelling into stems – transport – Attacking roots – water uptake – Destroying buds and shoots Pesticides are poisonous chemicals used to control organisms considered to be harmful on agriculture or organisms involved in disease transmission. Pesticides should be specific, non persistent (biodegradable) and shouldn't accumulation. Pest control cannot completely remove a pest. The point is to remove enough of a pest so the farmer can get a good profit return. Pests can also be controlled chemically. This involves the use of herbicides, fungicides, or insecticides to kill the pests. The chemicals can be sprayed onto the crop, applied as powders or smokes in enclosed areas, sprayed onto animals or added to animal feed. Advantages of chemical control: * Pests are destroyed quickly and fairly cheaply * Chemicals can be applied on a small level * Doesn't need a high level of skill * Very effective means of control Disadvantages of control: * Chemicals aren't specific and can damage non target insects. With the removal of insect predators, there may be a resurgence in the pest * Pesticides contain poisonous chemicals which could enter into food chains likely to then kill birds, fish or mammals. * Pests could become resistant to pesticides. * Chemical residue could harm humans Chlorinated organic chemicals such as DDT were constant and remained in the environment for long periods, which is not what is required of a modern pesticide. However DDT was over used and this led to resistance from many species of insects. The suitable insecticide is an effective pesticide at low quantities and kills harmful insects. Another key point is that it should have no environmental effects. Researcehrs are constantly making progress on developing on new compounds. In the latest generation of insecticides, the pyrethroid has been developed from the flower of the plant named Pyrethrum. However, the effect of the natural pyrethrum was found to be short term as it was quickly broken down by sunlight. Biochemists then used the natural pyrethrum as a beginning point to develop a much safer, stable compound, suitable for insect control in field crops. Farmers should spray their crops in early morning or late evening to avoid harming passing by bees and ladybirds. Chemical pest control may involve the use of: * Herbicides – for control of weeds * Insecticides – for control of insects * Fungicides – for control of fungi * Molluscicides – for control of slugs and snails There have been many problems with insecticides since the primary idea behind insecticides was to kill all the pests possible – the effects on non-target organisms wasn't looked into, some of which are beneficial. Biological control target natural enemies to maintain the population of pest species. A beneficial organism (agent) is deployed against a harmful organism (target). The purpose is to reduce the pest population down to a level which is economically profitable. If the pest population was completely wiped out then it would have a counter effect because there would be no food for the natural predator which would soon die out. Advantages of biological pest control: * Can provide long term control if population equilibrium is reached * Even though it is expensive in the short term (introductioin), it can work out cheaper in the longer term * Unlike chemical control, it's highly specific to a pest which means less chance of having an effect on non target organisms. * No environmental contamination * It can be used in a glasshouse situation Disadvantages of biological control * Success needs deep level of skill and research. This can be expensive. * Examples which have gained success are fairly few in number * A thorough amount of knowledge is required about the life cycle. * Possibility of releasing organisms with unknown ecological effects * Consistent input is needed to maintain a population stability There are advantages and disadvantages of both chemical and biological control. Integrated pest management is the merging of the two methods. It is seen as a very effective way of tackling pests. This is achieved by: * Varying cultivation techniques * Use of biological agents * Minimal and well-targeted use of highly selective pesticides. Deforestation is having a effect on the environment. They are being cut down for reasons such as: * Sale of valueable timber * Freeing of land * Clearing land for roads The trees are being cut down at a much faster rate than they can regenerate. The consequences of deforestation are: * Soil erosion – digging and ploughing loosen up the topsoil, which is aiding in the process of soil erosion. * The removal of vegetation affects the regional climate mainly by reducing rainfall which increases speed of desertification. * Deforestation of the watershed causes lowland flooding. The removal of vegetation on the higher slopes of valleys consequents in heavy rain sweeping exposed soil to the floods below. On the lower slopes, plants and leaf litter would act as a sponge and soak up water gradually released into the soil. Instead, due to the absence of plants, only evaporation occurs. This is generally slower than transpiration in returning water vapour to the atmosphere, so soil conditions become wetter. * Climate change – A reduction in the level of carbon dioxide from the atmosphere as there is less global synthesis. This leads to global warming. Cutting down forests hasn't much effect on global carbon dioxide levels however since forests burn rapidly releasing lots of carbon dioxide into the atmosphere which assists in acid rain and helps towards global warming. Destruction of natural habitats leads to reduction in biodiversity. It is estimated that around 50% of the earth's species live in the rainforests even though rain forests only take up around 10% of the earth's land. If natural habitats are exploited then it could make them become extinct. This may lead to a loss in medical properties of some tropical plants which haven't been looked into. Agricultural is way of combating deforestation. Possible solutions to problems of deforestation: * Managed forests involving the sustainable replanting and regeneration. * Providing protected areas to preserve species. There have been dramatic increases in the intensity and efficiency of commercial methods. This has meant that over-fishing is happening in many areas of the world. Fish are a renewable source. Over-fishing results in a depletion of younger fish, so that the breeding stock can't maintain previous population levels. If the rate at which they are removed exceeds that at which they have been produced, their supply is disappearing. Fishing isn't examined for possible negative issues. In a fish farm, fish are replaced by artificial breeding. However in the ocean, fish are taken out of the sea from humans with no aim to replace them by breeding. Over fishing often causes both a fall in the number of fish and a change in population structure: young smaller fish may become increasingly common as fishing fleets try to maintain the size of the fish they catch. Catching large numbers of small fish before they spawn can seriously reduce their ability of their species to reproduce. This could lead to a terrible fall in the local population of smaller fish. However fishing is likely to halt due to economic reasons, fishing is likely to stop before it can cause extinction. International agreements have been gained on control like: * Enforcing exclusion zones * Imposing quotas * Restricting the mesh size of nets – bigger nets may allow juvenile fish to escape and reproduce. * Having closed seasons for fishing