Nutrients: Difference between revisions
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|KeyReference=Bouwman et al., 2013; Bouwman et al., 2009; Van Drecht et al., 2009; | |KeyReference=Bouwman et al., 2013; Bouwman et al., 2009; Van Drecht et al., 2009; | ||
|Reference=Bouwman et al., 2011; Galloway et al., 2004; Zhang et al., 2010; Diaz and Rosenberg, 2008; UNEP, 2002; Rabalais, 2002; | |Reference=Bouwman et al., 2011; Galloway et al., 2004; Zhang et al., 2010; Diaz and Rosenberg, 2008; UNEP, 2002; Rabalais, 2002; | ||
|InputVar=Population; GDP per capita; Land cover, land use - grid; | |InputVar=Population; GDP per capita; Land cover, land use - grid; Fertilizer use efficiency; Animal stock; Livestock ration; Manure spreading fraction; Nitrogen deposition - grid; NH3 loss; Fraction of urban population; Actual crop and grass production - grid; | ||
|OutputVar=Ammonia emissions from nutrients; N and P discharge to surface water; Nutrient discharge to water surface; Soil N budget - grid; Soil P budget - grid; | |OutputVar=Ammonia emissions from nutrients; N and P discharge to surface water; Nutrient discharge to water surface; Soil N budget - grid; Soil P budget - grid; | ||
|Description=Human activities have accelerated the earth’s biogeochemical nitrogen (N) and phosphorus (P) cycles by increasing the use of fertilisers in agriculture ([[Bouwman et al., 2011]]). The changes in global nutrient cycles have both positive and negative effects. Increased use of N and P fertilisers has allowed for an increase in the production of food required to support a rapidly growing human population, and increasing per-capita consumption of particularly meat and milk ([[Galloway et al., 2004]]). This has also contributed to ongoing increases in yields, thereby making agriculture economically viable on a land area that has expanded much less than the harvested output. A side effect is that significant fractions of the mobilised N are lost through the emission of ammonia (NH3), nitrous oxide (N2O) and nitric oxide (NO) to ambient air. Ammonia contributes to eutrophication and acidification when deposited on land. Nitric oxide plays a role in tropospheric ozone chemistry, and nitrous oxide is a potent greenhouse gas. Also, large fractions of the mobilised N and P in watersheds enter the groundwater through leaching, and are released to surface waters through groundwater transport and surface runoff. Subsequently, nutrients in streams and rivers are transported towards coastal marine systems, reduced by retention but augmented by releases from point sources, such as sewage systems and industrial facilities. | |Description=Human activities have accelerated the earth’s biogeochemical nitrogen (N) and phosphorus (P) cycles by increasing the use of fertilisers in agriculture ([[Bouwman et al., 2011]]). The changes in global nutrient cycles have both positive and negative effects. Increased use of N and P fertilisers has allowed for an increase in the production of food required to support a rapidly growing human population, and increasing per-capita consumption of particularly meat and milk ([[Galloway et al., 2004]]). This has also contributed to ongoing increases in yields, thereby making agriculture economically viable on a land area that has expanded much less than the harvested output. A side effect is that significant fractions of the mobilised N are lost through the emission of ammonia (NH3), nitrous oxide (N2O) and nitric oxide (NO) to ambient air. Ammonia contributes to eutrophication and acidification when deposited on land. Nitric oxide plays a role in tropospheric ozone chemistry, and nitrous oxide is a potent greenhouse gas. Also, large fractions of the mobilised N and P in watersheds enter the groundwater through leaching, and are released to surface waters through groundwater transport and surface runoff. Subsequently, nutrients in streams and rivers are transported towards coastal marine systems, reduced by retention but augmented by releases from point sources, such as sewage systems and industrial facilities. | ||
Revision as of 18:04, 5 February 2014
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Key policy issues
- How will the increasing use of fertilisers affect terrestrial and marine ecosystems, with possible consequences for human health?
- To what extent can the negative impacts be reduced by more efficient nutrient management and wastewater treatment, while retaining the positive effects on food production and land productivity?