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Inputs of nutrients, such as nitrogen and phosphorus, are important in farming systems as they are critical in raising plant productivity, and a nutrient deficiency can impair soil fertility. A build up of surplus nutrients in excess of crop and forage needs can lead to losses representing a possible cause of economic inefficiency in nutrient use and also a source of potential environmental harm, in terms of water pollution (e.g. eutrophication of water), and air pollution (e.g. ammonia), while the sustainability of phosphorus resources is a concern as world reserves are diminishing.
Definition
Gross nutrient balances are calculated as the difference between the total quantity of nutrient inputs entering an agricultural system, and the quantity of nutrient outputs leaving the system. This calculation can be used as a proxy to reveal the status of environmental pressures, such as declining soil fertility in the case of a nutrient deficit, or for a nutrient surplus the risk of polluting soil, water and air.
Comparability
The nutrient balance indicators are expressed in terms of the kilograms of nutrient surplus (deficit) per hectare of agricultural land per annum, and in terms of changes in the physical quantities (tonnes) of nutrient surpluses (deficits). The former is an intensity indicator and the latter provide an indication of the trend and level of potential physical pressure of nutrient surpluses into the environment.
Long-term trends
The decrease in nutrient balance surpluses has contributed to reduced pressures on soil, water and air, although a third of OECD countries registered an increase in surpluses. Rising or large nitrogen surpluses are commonly a result of the intensification of livestock production, since the growth in the use of inorganic nitrogen fertilisers has been limited in most countries. Where adoption of nutrient management plans has been high, this has had an impact in reducing surpluses, but there is further potential to reduce nutrients to levels that are not environmentally damaging. In most countries there is considerable variation in the level and trends of regional nutrient balances around national averages.
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Source
Further information
Analytical publications
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OECD (1999), Environmental Indicators for Agriculture: Concepts and Framework, Volume 1, OECD, Paris.
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OECD (1999), Environmental Indicators for Agriculture: Issues and Design - “The York Workshop”, Volume 2, OECD, Paris.
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OECD (2007), Environmental Indicators for Agriculture: Volume 3, OECD, Paris.
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OECD (2008), Environmental Performance of OECD Agriculture since 1990, OECD, Paris.
Methodological publications
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OECD (2007), OECD Nitrogen Balance Handbook, only available online at website below, OECD, Paris.
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OECD (2008), OECD Phosphorus Balance Handbook, only available online at website below, OECD, Paris.
Online databases
Websites
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| Indicator in PDF |
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| Table |
| Gross agricultural nutrient balances |
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| 2.3. The main elements in the OECD gross nutrient (nitrogen and phosphorus) balance |
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| 2.4. Gross agricultural nitrogen and phosphorus balances |
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