A farm that is able to "produce perpetually", yet has negative effects on environmental quality elsewhere is not sustainable agriculture. An example of a case in which a global view may be warranted is over-application of synthetic fertilizer or animal manures, which can improve productivity of a farm but can pollute nearby rivers and coastal waters (eutrophication). The other extreme can also be undesirable, as the problem of low crop yields due to exhaustion of nutrients in the soil has been related to rainforest destruction, as in the case of slash and burn farming for livestock feed.
Agricultural activities contribute strongly to eutrophication and the spread of pollutions in the basin.
The chain of eutrophication begins with an overload of nutrients that enters the aquatic ecosystem. This schematic show various nutrient pathways and their effects. The future half of the diagram shows improved water quality based on better nutrient filtering.
Sustainability affects overall production, which must increase to meet the increasing food and fiber requirements as the world's human population expands to a projected 9.3 billion people by 2050. Increased production may come from creating new farmland, which may ameliorate carbon dioxide emissions if done through reclamation of desert as in the worlds, or may worsen emissions if done through slash and burn farming. Additionally, Genetically modified organism crops show promise for radically increasing crop yields, although many people and governments are apprehensive of this new farming method.
Genetically modified organisms (GMOs)
Genetically modified organism (GMO) is an organism that was changed using methods of modern biotechnology. In such organism defined gene for exactly defined characteristic from other organism has been inserted. GMO are microorganisms (bacteria, fungi, and viruses), plants and animals.
According to Slovene legislation ''GMO is an organism, with the exception of human beings, or a micro-organism, in which the genetic material has been altered in a way that does not occur naturally by mating or natural recombination.'' (Management of Genetically Modified Organisms Act (Official Gazette of RS No. 23/2005))
According to EU legislation ''GMO means an organism, with the exception of human beings, in which the genetic material has been altered in a way that does not occur naturally by mating and/or natural recombination.''(Directive 2001/18/EC of the European Parliament and of the Council of 12 March 2001 on the deliberate release into the environment of genetically modified organisms and repealing Council Directive 90/220/EEC - Commission Declaration)
According to international Cartagena Protocol ''Living Modified Organism (LMO) means any living organism that possesses a novel combination of genetic material obtained through the use of modern biotechnology.'' (Cartagena Protocol on Biosafety to the Convention on Biological Diversity)