Since the change of the agricultural production, there has been both positive and negative effects, with regards to the environment and the economy. New technologies, government policies, increased chemical use and the mechanisation of the farming world have all favoured maximizing crop production. There have, however been some significant costs. Topsoil depletion, groundwater contamination, decline of family farms, increased costs of production and reduction of species diversity.
The energy loss at each trophic level has meant that the energy humans receive is only a small percentage of the total amount of energy available to the sun as humans are most often the third or fourth trophic level in a food chain. Intensive farming practices have tried to ensure that as much of this energy as possible is transferred, thus increasing the productivity of the human food chain.
eg. Grass Cow Human
Natural ecosystems and agricultural ones differ mainly in the energy input and the productivity. In natural ecosystems, the sun is the sole source of energy and much of the land would be covered by forests if it were allowed to develop naturally, known as the climax community. This community is obtained through succession, in which simple communities are replaced by much more complex ones. Each successive community harbors many other life forms, and therefore having a great species diversity, for example, the desert and tropical rain forests are such climax communities. In order for the agricultural ecosystem to have a high productivity, prevention of this climax community developing is required. In order for this to happen, unwanted species must be removed leaving only the desired crop wanted to grow. This therefore requires an additional input of energy, which is used to plough fields, sow crops, remove weeds, suppress pests, prevent disease, feed animals and transport materials all for maximum growth and productivity. Food and fossil fuels are most often this additional energy, as the farms have become more mechanised, fuel supplies the energy to carry out such tasks.
The productivity is much higher in agricultural ecosystems as the additional input of energy reduces the effects of limiting factors. The suppression of other species gives little competition for light, carbon dioxide, nutrients and water which is needed for photosynthesis in plants and space is also available; resulting in most of the ground to be covered entirely by the desired crop. The fertilisers are added to provide extra essential minerals and ions and the pesticides are used to suppress pests and help prevent disease spreading.
The rate of photosynthesis relies upon the limiting factor, and by supplying this factor, the ecosystems become much more economically viable as the rate of photosynthesis and therefore food production is increased. This can be regulated using glasshouses and enclosed environments. This allows for the control and monitor of factors such as light intensity, carbon dioxide, nutrients, humidity and temperature.
Although the use of this intensive method has led to higher productivity of food, a reduction in species diversity and the diminishing variety of habitats within ecosystems has occurred as a result of this farming practice.
The removal of hedgerows and woodland, has increased the productivity by supplying more space for crops to grow and it is easier for the manoeuvre of large machinery. The weeds and pests that may live in hedgerows have also been minimized,...