IIASA chemical engineer Wilfried Winiwarter received a call in the fall of 2008 inviting him to bring his expertise in atmospheric modeling to the European Nitrogen Assessment project. Three years later, he has just completed, as lead author, the assessment’s chapter on future scenarios of nitrogen in Europe.
The landmark 600-page study, based on research by 200 European scientists, found that reactive nitrogen damages water, air and soil quality, causes harm to ecosystems and is a significant health threat to millions of people in Western Europe. Reactive nitrogen, a scarce resource in the natural environment, has been greatly increased by human activity, primarily the use of nitrogen-based fertilizer in agriculture.
The European Nitrogen Assessment found that excess nitrogen in the environment costs the European Union between €70 billion and €320 billion per year, more than double the value that nitrogen fertilizer use adds to European farm income.
Using IIASA’s GAINS model in concert with other models, Winiwarter found that although reactive nitrogen emissions—mostly in the form of nitrogen oxides—from the transportation and industrial sectors can be reduced over the next few decades, the levels of damaging nitrogen being released by agriculture will continue to rise. Reactive nitrogen from agriculture includes ammonia, nitrate, and nitrous oxides.
“With agriculture there are always a large number of people who need to have their concerns addressed,” Winiwarter says. “Efforts to change farming practices and reduce emissions will have to start with the large agro-industry farms where controls can have a substantial impact. Then you need to turn to the smaller farms.” It may not be necessary to change practices for individuals operating small hobby or subsistence farms, he said.
Agricultural practices differ from country to country, as do environmental conditions, which makes controlling reactive nitrogen emissions even more challenging, Winiwarter maintains. “It matters,” he says “whether you operate under summer temperatures of 30 or 20 °C (86 or 68 °F), and whether you have humid conditions or dry conditions. Temperature also affects soil chemistry and the evaporation of ammonia from manure and fertilizer.”
According to Winiwarter’s assessment, “agricultural nitrogen use is expected to remain the leading cause of nitrogen release to the environment, as options to reduce emissions are limited.” Major changes in the use of nitrogen in agriculture will occur, he adds, only if the extent of agricultural production changes. This could be triggered by decreasing population numbers in Europe, but also requires agriculture to put less emphasis on maximizing output.
Retained reactive nirogen - Fraction of reactive nitrogen in animal feed which is retained in animal tissue or edible animal products. Data from the European Nitrogen Assessment.
Because animal production and the cultivation of animal feed crops are responsible for high overall losses of nitrogen, Winiwarter says, changes in Europeans’ dietary habits could be an alternative path to reducing reactive nitrogen. “Agricultural activity may decrease strongly if the European population adopts a healthier ‘low meat’ diet leading to lower nitrogen losses related to animal husbandry,” he writes in the assessment. However, if agricultural land previously used for animal feed production is used to grow biofuel crops, nitrogen fertilizer may still be required, which means that the problem of reactive nitrogen emissions may continue.
For the immediate future, he says, “the nitrogen community is quite active in policy processes and there are many (involved in the assessment report) who will continue to work on the issue.” The next revisions for the 1999 United Nations Gothenburg Protocol, which sets emission ceilings for nitrogen oxides, ammonia and several other pollutants “should take account of the nitrogen assessment work when defining measures to be taken in the future,” he concludes.
Last edited: 28 August 2012
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