Executive summary

Nature of the issue

• Reactive nitrogen (Nr) has well-documented positive effects in agricultural and industrial production systems, human nutrition and food security. Limited Nr supply was a key constraint to European food and industrial production, which has been overcome by Nr from the Haber–Bosch process.

• Given the huge diversity in Nr uses, it becomes a major challenge to summarize an overall inventory of Nr benefits. This full list of benefits needs to be quantified if society is to develop sound approaches to optimize Nr management, balancing the benefits against the environmental threats.

Approaches

• When reviewing trends in European Nr production rates, including those from chemical and biological fixation processes, and the consumption of this Nr in human activities, agriculture is by far the largest sector driving Nr creation.

• Particular attention has been given to relationships between N application rates, productivity and quality of products from major crops and livestock types, including consideration of the mechanisms underlying variations in N response/outputs and the derived impacts on land use and land requirements.

Key findings/state of knowledge

• The economic value of N benefits to the European economy is very substantial. Almost half of the global food can be produced because of Nr from the Haber–Bosch, and cereal yields in Europe without fertilizer would only amount to half to two-thirds of those with fertilizer application at economically optimal rates.

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Executive summary

Nature of the problem

• The future effects of nitrogen in the environment will depend on the extent of nitrogen use and the practical application techniques of nitrogen in a similar way as in the past. Projections and scenarios are appropriate tools for extrapolating current knowledge into the future. However, these tools will not allow future system turnovers to be predicted.

Approaches

• In principle, scenarios of nitrogen use follow the approaches currently used for air pollution, climate, or ecosystem projections. Short-term projections (to 2030) are developed using a ‘baseline’ path of development, which considers abatement options that are consistent with European policy. For medium-term projections (to 2050) and long-term projections, the European Nitrogen Assessment (ENA) applies a ‘storyline’ approach similar to that used in the IPCC SRES scenarios. Beyond 2050 in particular, such storylines also take into account technological and behavioral shifts.

Key findings/state of knowledge

• The ENA distinguishes between driver-oriented and effect-oriented factors determining nitrogen use. Parameters that cause changes in nitrogen fixation or application are called drivers. In a driver-based approach, it is assumed that any variation of these parameters will also trigger a change in nitrogen pollution. In an effect-based approach, as the adverse effects of nitrogen become evident in the environment, introduction of nitrogen abatement legislation requiring the application of more efficient abatement measures is expected. This approach needs to rely on a target that is likely to be maintained in the future (e.g. human health). Nitrogen abatement legislation based on such targets will aim to counter any growth in adverse environmental effects that occur as a result of increased nitrogen application.

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