Energy and Food Production
Introduction
Net productivity
Gross productivity – respiratory loss
Chemical pesticides and biological agents
Intensive rearing of animals
Prioritising land
Controlling the effects of chemicals
Drawing ethical boundaries
Introduction
As seen in the previous topic on energy transfer, plants produce a great deal of energy which is used up increasingly at every trophic level. This is the basis on which decisions are made in agriculture and rearing of domestic livestock.
In the wild, both plants and animals are subject to a lot of energy loss due to pests, physical activity or insufficient nutrients. This results in a relatively inefficient flow of energy between trophic levels. We think of this in terms of net productivity.
Net productivity is equal to gross productivity minus respiratory loss.
In both terms, productivity refers to the amount of leftover useful tissue such as cereals or animal flesh.
As opposed to the wild, in human-made growth environments this respiratory loss is kept as low as possible. Extreme measures are taken to achieve this, which Include:
Chemical pesticides and biological agents
The use of chemical pesticides and biological agents to kill all or certain organisms which may infect or feed on plants e.g. insects, fungi, small animals.
Intensive rearing of animals
Intensive rearing of animals which includes keeping them indoors and in confined spaces to prevent their energy being lost on movement; and administering antibiotics to prevent mass spread of infection
To enhance plant growth fertilisers are used, whether natural (manure) or artificial.
A strategy to maximise net productivity is an…..
