Call for new approach to nitrogen management

Europe should take an integrated approach to nitrogen management. This is the main message of the European Nitrogen Assessment, a new report launched during the "Nitrogen and Global Change" conference, in Edinburgh (UK) from 11–14 April, 2011.

  A threat to water quality. Photo:Dave Wild/Creative Commons

The scientists conclude that policy makers have so far tackled the nitrogen issue in a piecemeal fashion, which means that policies are usually separated by media – for example air, land and water – by issues, such as climate, biodiversity waste – or by various forms of reactive nitrogen (nitrogen oxides, nitrous oxide or ammonia). The assessment recommends seven key actions for reducing pollution from nitrogen, including improving nitrogen use efficiency in crop and animal production, improved emission abatement technologies for both stationary combustion sources and vehicles, increasing energy efficiency and use of alternative energy sources, recycling nitrogen from waste water systems and lowering meat consumption, particularly beef.

Over the past century humans have caused unprecedented changes to the global nitrogen cycle, converting atmospheric nitrogen (N2) into many reactive nitrogen (Nr) forms, doubling the total fixation of nitrogen globally and more than tripling it in Europe. Five key societal threats from Nr can be identified: to water quality, air quality, greenhouse balance, ecosystems and biodiversity, and soil quality.

Cost-benefit analysis highlights how the overall environmental costs of all Nr losses in Europe (estimated at €70–320 billion per year at current rates) outweigh the direct economic benefits of Nr in agriculture. The highest societal costs are associated with loss of air quality and water quality, linked to impacts on ecosystems and especially on human health.

The European Nitrogen Assessment (ENA) was established to help synthesise the science and understanding of nitrogen into a form that is useful to governments and society. The Assessment provides a European contribution to the International Nitrogen Initiative (INI).

Reactive nitrogen is a threat to air quality because air pollution by nitrogen oxides (NOx) and ammonia (NH3) causes formation of secondary particulate matter (PM), while emissions of NOx also increase levels of nitrogen dioxide (NO2) and tropospheric ozone (O3). All of these are causes for respiratory problems and cancers for humans, while ozone causes damage to crops and other vegetation, as well as to buildings and other cultural heritage.

It is estimated that PM contributes to several hundred thousand premature deaths annually in the EU, leading to a reduction in life expectancy due to PM of 6–12 months across most of central Europe. Reactive nitrogen contributes up to 30–70 per cent of the PM by mass.

Although NOx emission reductions over the last few decades in the EU have reduced peak ozone concentrations, background tropospheric ozone concentrations continue to increase. By comparison to the limited progress in reducing NOx emissions, there has been even less success in controlling agricultural ammonia emissions, which therefore contribute to an increasing share of the European air pollution burden.

Seven key actions for better management of the nitrogen cascade

1. Improving nitrogen use efficiency in crop production
2. Improving nitrogen use efficiency in animal production
3. Increasing the fertiliser nitrogen equivalence value of animal manure

Transport and Industry
4. Low-emission combustion and energy-efficient systems

Wastewater treatment
5. Recycling nitrogen (and phosphorus) from wastewater systems

Societal consumption patterns
6. Energy and transport saving
7. Lowering the human consumption of animal protein

Key Action 4 involves technical measures that are already being combined with public incentives for energy saving and less polluting transport (Key Action 6), linking Nr, air pollution and climate policies. Similarly, each of the Key Actions in the food chain (1–3, 7) offers co-benefits with climate mitigation and the management of other nutrients, including phosphorus. Given the limited success so far in reducing agricultural Nr emissions, more effort is needed to link the Key Actions, both to learn from the successes and to ensure equitability between sectors.

Source: ENA website, 11 April 2011
More information, and to download the "Summary for policy makers" or the full report: Nitrogen in Europe at

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