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Managing reactive nitrogen (Nr) to achieve a sustainable balance between production of food, feed and fiber, and environmental protection is a grand challenge in the context of an increasingly affluent society. Here, we propose a novel framework for national nitrogen (N) assessments enabling a more consistent comparison of the uses, losses and impacts of Nr between countries, and improvement of Nr management for sustainable development at national and regional scales. This framework includes four key components: national scale N budgets, validation of N fluxes, cost-benefit analysis and Nr management strategies. We identify four critical factors for Nr management to achieve the sustainable development goals: N use efficiency (NUE), Nr recycling ratio (e.g., ratio of livestock excretion applied to cropland), human dietary patterns and food waste ratio. This framework was partly adopted from the European Nitrogen Assessment and now is successfully applied to China, where it contributed to trigger policy interventions toward improvements for future sustainable use of Nr. We demonstrate how other countries can also benefit from the application our framework, in order to include sustainable Nr management under future challenges of growing population, hence contributing to the achievement of some key sustainable development goals (SDGs).

Despite its relevance to most UN Sustainable Development Goals (SDGs), nitrogen pollution still lacks broad visibility and coordinated global governance. A new goal to “halve nitrogen waste” by 2030 would save US$100 billion annually, contributing to post-coronavirus disease 2019 (COVID-19) economic recovery and multiple SDGs. The scientific community is working with the UN to coordinate and accelerate the necessary action.

Ammonia and ammonium have received less attention than other forms of air pollution, with limited progress in controlling emissions at UK, European and global scales. By contrast, these compounds have been of significant past interest to science and society, the recollection of which can inform future strategies. Sal ammoniac ( nūshādir , nao sha ) is found to have been extremely valuable in long-distance trade ( ca AD 600–1150) from Egypt and China, where 6–8 kg N could purchase a human life, while air pollution associated with nūshādir collection was attributed to this nitrogen form. Ammonia was one of the keys to alchemy—seen as an early experimental mesocosm to understand the world—and later became of interest as ‘alkaline air’ within the eighteenth century development of pneumatic chemistry. The same economic, chemical and environmental properties are found to make ammonia and ammonium of huge relevance today. Successful control of acidifying SO 2 and NO x emissions leaves atmospheric NH 3 in excess in many areas, contributing to particulate matter (PM 2.5 ) formation, while leading to a new significance of alkaline air, with adverse impacts on natural ecosystems. Investigations of epiphytic lichens and bog ecosystems show how the alkalinity effect of NH 3 may explain its having three to five times the adverse effect of ammonium and nitrate, respectively. It is concluded that future air pollution policy should no longer neglect ammonia. Progress is likely to be mobilized by emphasizing the lost economic value of global N emissions ($200 billion yr −1 ), as part of developing the circular economy for sustainable nitrogen management. This article is part of a discussion meeting issue ‘Air quality, past present and future’.

Human interference with the nitrogen cycle has doubled reactive nitrogen inputs to the global biosphere over the past century, leading to changes across multiple environmental issues that require urgent action. Nitrogen fertilizers and biological nitrogen fixation have allowed benefits of increased crop harvest and livestock production, while in some areas there is insufficient nitrogen to fertilize crops. Whether in excess or deficit, nitrogen losses from its inefficient use are causing a combination of freshwater and marine pollution, air pollution, alteration of climate balance, stratospheric ozone loss, biodiversity loss and reduction of soil quality. The resulting nitrogen pollution affects human health, well-being and livelihoods. Scientific efforts have begun to bring these issues together. However, there is still a high degree of fragmentation between research on the different benefits and threats of reactive nitrogen and between the respective policy frameworks, especially at the global scale. We argue that a more joined-up approach to managing the global nitrogen cycle is needed to develop the ‘gravity of common cause’ between nitrogen issues and to avoid policy trade-offs. We describe how a coherent system for science evidence provision is being developed to support policy development through the ‘International Nitrogen Management System’ (INMS). There is now a matching challenge to bring together the multiple policy agreements relevant for nitrogen as a foundation to address synergies/trade-offs and to set priorities. Based on review of existing frameworks, we outline the concept for an Interconvention nitrogen coordination mechanism. This could make a major contribution to multiple Sustainable Development Goals by stimulating the next generation of international nitrogen strategies: maximizing the benefits of efficient nitrogen use, while minimizing its many environmental threats.

Humans have altered the natural nitrogen and phosphorus biogeochemical cycles by the massive input of fertilizers to the agricultural system to boost production. As a result a large amount of nitrogen and phosphorus have been mobilised and delivered to the environment, creating threats to aquatic and terrestrial ecosystem functioning and human health. Based on recent studies published in the literature, this research describes and quantifies the main fluxes of the current global nitrogen and phosphorus cycles (year 2000-2010).

Ammonia emissions harm humans and the environment. An analysis shows that satellites can locate sources precisely, and could thus help to monitor compliance with international agreements to limit such emissions. High-precision maps of ammonia emissions derived from satellite data.

Human activities have massively altered the global nitrogen (N) cycle, doubling annual production of reactive N (Nr) compounds from atmospheric dinitrogen (N2). The use of 120 Mt year−1 fertilizer N, with a global terrestrial/atmospheric N fixation of 285 Mt year−1, has provided huge benefits for global food production. However, nitrogen use efficiency (NUE) of the world food system is only ∼15%. The lost Nr creates a cascade of air and water pollution and greenhouse gas emissions, until it is eventually denitrified back to N2. India clearly illustrates a dual N challenge for food and environment, consuming 17 Mt of N fertilizer annually (14% of the global total), which has increased since 1970 at 6% year−1 approximately. Emissions of nitrogen oxides (NOx) from combustion sources are also increasing rapidly at 6.5% year−1 currently. By comparison, population growth rate is lower (2% year−1), while ammonia (NH3) emission increase is even less (1%), pertaining to smaller changes in livestock numbers. At current rate, Indian NOx emissions will exceed NH3 emissions by 2055. India currently loses Nr worth US$10 billion year−1 as fertilizer value, while costs of Nr to health, ecosystems, and climate are estimated at US$75 (38–151) billion year−1. Only a small fraction of the Indian population consumes animal products, hence per capita Nr use and pollution is much less than in many developed countries. However, rates of meat consumption are increasing. While published projections from the UN Food and Agriculture Organization anticipate a doubling of South Asian fertilizer consumption from 2006 to 2050 (equivalent to 1.9% year−1 increase), these projections lack transparency and require reevaluation. In practice, the future nitrogen cycle for India will depend on scientific advances in agronomy, genetics and environment, and the extent to which government and society grasp the emerging opportunities for optimizing N management.

One of the 'grand challenges' of this age is the anthropogenic impact exerted on the nitrogen cycle. Issues of concern range from an excess of fixed nitrogen resulting in environmental pressures for some regions, while for other regions insufficient fixed nitrogen affects food security and may lead to health risks. To address these issues, nitrogen needs to be managed in an integrated fashion, at a variety of scales (from global to local). Such management has to be based on a thorough understanding of the sources of reactive nitrogen released into the environment, its deposition and effects. This requires a comprehensive assessment of the key drivers of changes in the nitrogen cycle both spatially, at the field, regional and global scale and over time. In this focus issue, we address the challenges of managing reactive nitrogen in the context of food production and its impacts on human and ecosystem health. In addition, we discuss the scope for and design of management approaches in regions with too much and too little nitrogen. This focus issue includes several contributions from authors who participated at the N2013 conference in Kampala in November 2013, where delegates compiled and agreed upon the 'Kampala Statement-for-Action on Reactive Nitrogen in Africa and Globally'. These contributions further underline scientifically the claims of the 'Kampala Statement', that simultaneously reducing pollution and increasing nitrogen available in the food system, by improved nitrogen management offers win-wins for environment, health and food security in both developing and developed economies. The specific messages conveyed in the Kampala Statement focus on improving nitrogen management (I), including the reduction of nitrogen losses from agriculture, industry, transport and energy sectors, as well as improving waste treatment and informing individuals and institutions (II). Highlighting the need for innovation and increased awareness among stakeholders (III) and the identification of policy and technology solutions to tackle global nitrogen management issues (IV), this will enable countries to fulfil their regional and global commitments.

1. IntroductionAmong the many environment and development challenges facing humanity, it is fair to say thatnutrients do not currently feature so regularly in the newspapers, radio and television. The mediatends to prefer easy single issues which affect our daily lives in a clear-cut way.The role of carbon in climate change is a good example. We all depend on climate. Burning fossilfuels makes more carbon dioxide, tending to change temperature and rainfall patterns, to which wecan easily relate. The science is complex, but it is a simple message for the public to understand. Itdoes not take long to think of several other easily grasped threats, like urban air pollution, poordrinking water, or even the occurrence of horsemeat in food chains.Itisperhapsforthesereasonsthattheroleofnutrients in environmental change has received muchless public attention. After all, nutrients – including nitrogen, phosphorus and many micronutrients –playmultiple roles in our world; they affect many biogeochemical processes and they lead to a plethora ofinteracting threats. If we are not careful, we can quic kly get buried in the complexity of the different waysin which our lives are affected by these elements. The outcome is that it can become hard to convey thescience of global nutrient cycles in a way that the public can understand.These are points about which we have given substantial thought as we contributed to a recentlylaunched report Our Nutrient World: The challenge to produce more food and energy with less pollution(Sutton et al., 2013). The report was commissioned by the United Nations Environment Programme(UNEP) and conducted by the Global Partnership on Nutrient Management in cooperation with theInternational Nitrogen Initiative. The commission was not to provide a full scientific assessment, butrather to develop a global overview of the challenges associated with nutrient management. Drawingon existing knowledge, the aim was to distill the nature of the nutrient challenge answering clearly:why should anyone care, how has the problem got worse, what is already being done, and what stillneeds to be done?Contents lists available at SciVerse ScienceDirectjournal homepage:www.elsevier.com/locate/envdev

Nitrogen (N) fertilisers help ensure food security for many regions in the world, but excess or inappropriate use can have serious impacts on both human and environmental health (e.g. threatening air, soil, and water quality, reducing biodiversity and disrupting of greenhouse gas balance). While losses are exacerbated by the decoupling of animal and crop production systems, there are many opportunities to reduce N pollution and increase productivity simultaneously. On the 26th and 27th of March 2015, delegates from diverse backgrounds met at the Second BASF Fireside Chat to discuss these issues and explore possible solutions. Stakeholders from some regions emphasised the desire to avoid simplistic regulations, encouraging the empowerment of farmers to develop their own solutions. Other regions highlighted the need for more effective government intervention. This applied both for adoption of emission mitigation methods in regions of excess, as well as for good governance and infrastructure to improve fertiliser supply in regions of too little. A core message was that, although strategies to increase N use efficiency vary between global regions, there are substantial common themes, the shared development of which could greatly strengthen global action. These challenges are now being taken up by the International Nitrogen Initiative and the United Nations Environment Programme. With financial support from the Global Environment Facility, they are working towards an International Nitrogen Management System (INMS) to provide coordinated scientific support for international N policy-making.

This chapter summarises the information in the preceding chapters, which builds on the outcomes of an Expert Workshop held by the UNECE Task Force on Reactive Nitrogen in October 2010 in Paris, France, which examined the state-of-the-art regarding abatement measures for ammonia in agriculture. Cost information is provided by farm activity and abatement measure, including a discussion on integrated nitrogen management at the farm scale. The chapter also reports the conclusions of the Expert Workshop, noting the finding that in many cases the costs for the abatement techniques were cheaper than previously estimated. Wider policy contexts of the information are explored, including identifying priority measures for ammonia abatement and links to Annex IX of the Gothenburg Protocol.

This chapter presents an overview of the volume, introducing the background and setting out the aims and scope of the workshop and this book. Ammonia emissions primarily originate from agricultural sources and present a substantial contribution to a wide range of environmental problems (see as well Sutton et al., Atmospheric ammonia – detecting emission changes and environmental impacts – results of an expert workshop under the convention on long-range transboundary air pollution. Springer, Heidelberg, 2009; Managing the European nitrogen problem: a proposed strategy for integration of European research on the multiple effects of reactive nitrogen. Centre for Ecology & Hydrology, Edinburgh, 2009; The European nitrogen assessment. Cambridge University Press, Cambridge, 2011; Our nutrient world: the challenge to produce more food and energy with less pollution. Global overview of nutrient management. Centre for Ecology & Hydrology, Edinburgh, 2013; Philos Trans R Soc London, Ser B 368(1621):20130166, 2013), ranging from the deposition of acidifying substances and excess nutrients on soils, the formation of secondary inorganic aerosols, climate change and nutrient loads for freshwater and coastal ecosystems (Galloway et al., Bioscience 53:341–356, 2003). Yet, ammonia emissions have to date not been subject to stringent emission control policies, in contrast to sulphur dioxide or nitrogen oxides. As a consequence, ammonia emissions and the agricultural activities they originate from are discussed in detail, with the aim to identify the most promising emission sources and policy options to reduce their harmful environmental effects.

In this chapter, we present a series of country case studies, addressing specific challenges of reducing ammonia emissions and managing nitrogen on farm and field scale. Section 8.1 introduces nitrogen management activities in an intensively farmed region of Italy, while Sect. 8.2 addresses aspects of animal feed in Swiss pig farming. The following Sect. (8.3) illustrates N management in cattle and poultry operations in Switzerland. The assessment of ammonia abatement cost in dairy farming in the Russian Federation is covered in Sect. 8.4, with Sect. 8.5 discussing the costs of adoption of low ammonia emission slurry application methods on grassland in Ireland. A further case study on slurry application addresses the costs incurred by the trailing hose technique and by slurry dilution with water under Swiss frame conditions (Sect. 8.6). Section 8.7 highlights the estimated cost of abating volatilized ammonia from urea by urease inhibitors in the EU, and finally Sect. 8.8 discusses potential N2O reduction associated with the use of urease inhibitors in Spain (Authors of this section: Stefan Reis1,2, Mark A. Sutton1, Clare Howard1,3 (1) NERC Centre for Ecology & Hydrology, Bush Estate, Penicuik, EH26 0QB, UK; (2) Knowledge Spa, University of Exeter Medical School, Truro, TR1 3HD, UK; (3) School of Geosciences, University of Edinburgh, Institute of Geography, Drummond Street, Edinburgh, EH8 9XP, UK).

List of contributors Preface Summary for policymakers Technical summary 1. Assessing our nitrogen inheritance Part I. Nitrogen in Europe: The Present Position: 2. The European nitrogen problem in a global perspective 3. Benefits of nitrogen for food fibre and industrial production 4. Nitrogen in current European policies 5. The challenge to integrate nitrogen science and policies Part II. Nitrogen Processing in the Biosphere: 6. Nitrogen processes in terrestrial ecosystems 7. Nitrogen processes in aquatic ecosystems 8. Nitrogen processes in coastal and marine ecosystems 9. Nitrogen processes in the atmosphere Part III. Nitrogen Flows and Fate at Multiple Scales: 10. Nitrogen flows in farming systems across Europe 11. Nitrogen flows and fate in rural landscapes 12. Nitrogen flows and fate in urban landscapes 13. Nitrogen flows from European watersheds to coastal marine waters 14. Atmospheric transport and deposition of nitrogen in Europe 15. Geographic variation in terrestrial nitrogen budgets across Europe 16. Integrating nitrogen fluxes at the European scale Part IV. Key Societal Threats of Nitrogen: 17. Nitrogen as a threat to European water quality 18. Nitrogen as a threat to European air quality 19. Nitrogen as a threat to the European greenhouse balance 20. Nitrogen as a threat to European terrestrial biodiversity 21. Nitrogen as a threat to European soil quality Part V. European Nitrogen Policies and Future Challenges: 22. Costs and benefits of nitrogen in the environment 23. Developing integrated approaches to nitrogen management 24. Future scenarios of nitrogen in Europe 25. Coordinating European nitrogen policies between directives and international conventions 26. Societal choice and communicating the European nitrogen challenge Glossary Index.