To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Nitrogen (N) budgets of agricultural systems give important information for assessing the impact of N inputs on the environment, and identify levers for action.
N budgets of agro-ecosystems in the 27 EU countries are established for the year 2000, considering N inputs by fertiliser application, manure excretion, atmospheric deposition and crop fixation, and N outputs by plant uptake, gaseous emissions, mineralisation, leaching and runoff.
Country N budgets for agro-ecosystems are based on the models INTEGRATOR, IDEAg, MITERRA and IMAGE. Fine geographic distribution is depicted with the former two models, which have higher spatial resolution. INTEGRATOR is the only available model for calculating non-agricultural terrestrial N budgets systems.
Key findings/state of knowledge
For EU-27, the models estimate a comparable total N input in European agriculture, i.e. 23.3–25.7 Mton N yr−1, but N uptake varies largely from 11.3–15.4 Mton N yr−1, leading to total N surpluses varying from 10.4–13.2 Mton N yr−1. Despite this variation, the overall difference at EU-27 is small for the emissions of NH3 (2.8–3.1 Mton N yr−1) and N2O (0.33–0.43 Mton N yr−1) but estimates vary largely at a regional scale. The estimated sum of N leaching and runoff at EU-27 is roughly equal to the sum of NH3, N2O and NOx emissions to the atmosphere, but estimates vary by a factor two, from 2.7 to 6.3 Mton N yr−1.
Reactive nitrogen (Nr) is of fundamental importance in biological and chemical processes in the atmosphere–biosphere system, altering the Earth's climate balance in many ways. These include the direct and indirect emissions of nitrous oxide (N2O), atmospheric Nr deposition and tropospheric ozone formation (O3), both of which alter the biospheric CO2 sink, Nr supply effects on CH4 emissions, and the formation of secondary atmospheric aerosols resulting from the emissions of nitrogen oxides (NOx) and ammonia (NH3).
Human production and release of Nr into the environment is thus expected to have been an important driver of European greenhouse balance. Until now, no assessment has been made of how much of an effect European Nr emissions are having on net warming or cooling.
This chapter summarizes current knowledge of the role of Nr for global warming. Particular attention is given to the consequences of atmospheric Nr emissions. The chapter draws on inventory data and review of the literature to assess the contribution of anthropogenic atmospheric Nr emissons to the overall change in radiative forcing (between 1750 and 2005) that can be attributed to activities in Europe.
The use of Nr fertilizers has major additional effects on climate balance by allowing increased crop and feed production and larger populations of livestock and humans, but these indirect effects are not assessed here.
Europe, and especially the European Union (EU), has many governmental policy measures aimed at decreasing unwanted reactive nitrogen (Nr) emissions from combustion, agriculture and urban wastes. Many of these policy measures have an ‘effects-based approach’, and focus on single Nr compounds, single sectors and either on air or waters.
This chapter addresses the origin, objectives and targets of EU policy measures related to Nr emissions, considers which instruments are being used to implement the policies and briefly discusses the effects of the policy measures.
The chapter starts with a brief description of the basic elements of governmental policy measures.
A review of the main international conventions and EU policies related to emissions of Nr to air and water is then provided.
Finally the chapter provides a semi-quantitative assessment of the effectiveness and efficiency of European policy measures.
Key findings/state of knowledge
International conventions and other treaties have played a key role in raising awareness and establishing policy measures for Nr emissions abatement in EU through so-called Directives and Regulations.
There are many different EU Directives, often addressing individual Nr compounds from individual sectors (e.g. NOx emissions from combustion; NH3 emissions from agriculture, pollution of groundwater and surface water by nitrates from agriculture, discharge of total nitrogen from urban sewage to surface waters).
Too much nitrogen harms the environment and the economy
Over the past century humans have caused unprecedented changes to the global nitrogen cycle, converting atmospheric di-nitrogen (N2) into many reactive nitrogen (Nr) forms, doubling the total fixation of Nr globally and more than tripling it in Europe.
The increased use of Nr as fertilizer allows a growing world population, but has considerable adverse effects on the environment and human health. Five key societal threats of 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.
Nitrogen cascade and budgets
The different forms of Nr inter-convert through the environment, so that one atom of Nr may take part in many environmental effects, until it is immobilized or eventually denitrified back to N2. The fate of anthropogenic Nr can therefore be seen as a cascade of Nr forms and effects. The cascade highlights how policy responses to different Nr forms and issues are inter-related, and that a holistic approach is needed, maximizing the abatement synergies and minimizing the trade-offs.
Environmental problems related to nitrogen concern all economic sectors and impact all media: atmosphere, pedosphere, hydrosphere and anthroposphere.
Therefore, the integration of fluxes allows an overall coverage of problems related to reactive nitrogen (Nr) in the environment, which is not accessible from sectoral approaches or by focusing on specific media.
This chapter presents a set of high resolution maps showing key elements of the N flux budget across Europe, including N2 and Nr fluxes.
Comparative nitrogen budgets are also presented for a range of European countries, highlighting the most efficient strategies for mitigating Nr problems at a national scale. A new European Nitrogen Budget (EU-27) is presented on the basis of state-of-the-art Europe-wide models and databases focusing on different segments of Europe's society.
From c. 18 Tg Nr yr−1 input to agriculture in the EU-27, only about 7 Tg Nr yr−1 find their way to the consumer or are further processed by industry.
Some 3.7 Tg Nr yr−1 is released by the burning of fossil fuels in the EU-27, whereby the contribution of the industry and energy sectors is equal to that of the transport sector. More than 8 Tg Nr yr−1 are disposed of to the hydrosphere, while the EU-27 is a net exporter of reactive nitrogen through atmospheric transport of c. 2.3 Tg Nr yr−1.
The largest single sink for Nr appears to be denitrification to N2 in European coastal shelf regions (potentially as large as the input of mineral fertilizer, about 11 Tg N yr–1 for the EU-27); however, this sink is also the most uncertain, because of the uncertainty of Nr import from the open ocean.
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.
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.
Email your librarian or administrator to recommend adding this to your organisation's collection.