Ecosystems, Sustainability and Animal Agriculture

          As the human population increases, the amount of food supplies is becoming more and more important; thus Agriculture has become one of the most observed areas. Several experiments are carried out to find ways to optimize energy capture and prevent wasting. Mathematics is also introduced in to agricultural practices because people have also started to pay more attention in to efficiency and sustainability of their farms, trying to calculate energy input and output ratios. Energy outputs are estimated by the direct conversion of product yields of mass to energy; for example a corn grain yield of 7000 kg is equivalent to a yield of about 24.5 million kcal, but determining energy input is much harder because there are a lot of kinds of input like labour, transportation and machinery; and to make the matters worse they are hard to quantify. Nevertheless these values will provide information about the dependence on exogenous energy sources.

The Ecosystem Concept

            An ecosystem is defined as an assemblage of organisms and their associated chemical and physical environment (Briske and Heitschmidt, 1991). An ecosystem can be essentially anything from a fish bowl to a country providing we can define its boundaries. It is made up of four components, one living and three non living. The abiotic (non living) component defines the chemical and physical environment of the biotic (living) component. These could be the atmosphere, climate and the soil. The three biotic components are the Producers which are organisms that capture solar (Sun) energy, Consumers which obtain their energy by consuming other organisms and the final components would be the Decomposers which are usually bacteria or fungi; they decompose unused material and recycle them back to the ecosystem to be used again. (see http://www.the-farm-business-gym.com/images/solar-flow-pyramid500.jpg)

         Everything in an ecosystem is recycled but the rules of thermodynamics however, decrease the efficiency of energy flow between trophic levels because most of the energy is converted to heat energy, which is useless (unless a mechanism has been setup to use it). Nitrogen, carbon, oxygen and water are all re-used within an ecosystem very efficiently in contrast to energy.

Agriculture

         Agriculture is defined as the business of managing resources to capture energy from the Sun and transfer it to people. So success in this area is closely linked with the three key factors which are the efficiency of capture of solar energy, harnessing and assimilation of that energy. There are several practices which attempt to improve all these points; like irrigation and fertilization which enables plants to grow and live in optimum conditions,  using insecticides which eliminates the insects from the food chains so the energy is transferred directly to humans and doctoring sick animals which increases the performances of these organisms.

Sustainable Agriculture

         Sustainable agriculture is defined as an agriculture that can be practiced continually for eternity. It must not require any exogenous energy to function. This type is becoming more and more important because the amount of fossil fuels is starting to come down to alarmingly low levels; but there comes a major problem, fossil fuels are the reason that agriculturalists produce an abundance of food. As the use of fertilizers and fossil fuels are increased the yield increases also but not in proportion so the energy output/input ratio decreases. This brings a challenge to scientists to develop technology which will maintain the high yields of agricultural products but also increasing the ecological deficiencies.

Tests and Results

         Three experiments were done to see which agricultural practice is the most efficient in energy transport. First one was calving animals in spring until they are grown to a considerable size then slaughtered, second one, calving them in spring then stocking them then slaughtering, and the final one is calving the animals in autumn then stocking then slaughtering.

The results showed that all the practices were heavily reliant on fossil fuels, which is not good news as they are non renewable. The machines used, fertilisers etc, all require fossil fuels at some point.

Discussion

         How are we going to carry on like this? The uncertainty is, how long will the fossil fuels last for; and what are the potential hazards of pollutants like fertilizers?

Conclusion

         Humans always occupy the second or the third trophic levels and in some cases wholly by themselves. Funny thing is that we don’t eat everything; foods have to be flavourful and tender so the challenge is to develop technology that will enhance animals so that they produce more from less and high quality too. This problem is made more complex by the fact that the human population of the world is increasing by time.

References

- Heitschmidt, R. Short, R. Grings, E. 1996. Ecosystems, Sustainability and Animal Agriculture. Journal of Animal Science 74, pp.1395-1405

- www.wikipedia.org/ecology