Workshop on integrated sustainable nitrogen managementBrussels, 30 September – 1 October 2019

Meeting report

This workshop was jointly organised by the European Commission and the Task Force on Reactive Nitrogen under the UNECE Air Convention.

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Introduction

Towards guidance on integrated sustainable nitrogen management

Policy overview

Break-out sessionsPrinciples of integrated sustainable nitrogen management

Livestock housing/feeding and manure processing and storageField application of inorganic fertilisers and manure

Land use and landscape management

Conclusion: The way forward

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Introduction

Nitrogen in the form of dinitrogen (N2) makes up 78% of every breath we take, while compounds containing nitrogen are essential for the processes of life. Howev-er, nitrogen can also take more harmful forms or occur in excess, creating problems for the environment and human health.

Reactive forms of nitrogen include ammonia (NH3), nitrous oxide (N2O), nitric oxide (NO), nitrogen oxides (NOx), nitrite (NO2), nitrate (NO3) and ammonium (NH4). These can cascade through the environment, readily transform into other forms that are mobile in both air and water, and contribute to a range of pol-lution problems.

In agricultural systems, especially, finding the right levels of nitrogen input is vital for maintaining live-stock and crop productivity, while minimising the out-put of reactive forms of nitrogen.

EU legislation addresses this challenge, and reactive ni-trogen pollution of air, water and soil have been reduced over time. However, the problems are far from solved.

At international level, a Task Force on Reactive Nitro-gen (TFRN) was established in 2007 under UNECE’s Air Convention on Long Range Transboundary Air Pollution (the Air Convention). In 2015, the Air Con-vention published a detailed guidance document on how to reduce ammonia emissions from agriculture, based on the work of TFRN. This guidance document helps UNECE countries to prepare their own ammonia abatement codes.

The ammonia guidance, however, focused only on air pollution aspects. With support from the European Commission, TFRN launched in 2016 a complement-ing initiative to address the reduction of multiple

forms of nitrogen pollution. As part of this process, a workshop on integrated sustainable nitrogen man-agement was held in Brussels on 30 September – 1 October 2019.

This workshop brought together 100 experts, most-ly from the EU but also from UNECE Air Convention parties in North America and in Eastern Europe, the Caucasus and Central Asia. Participants included sci-entists, policymakers, farmers, and representatives from industry and NGOs.

The goal was to discuss and improve a draft guid-ance document on an integrated sustainable ap-proach to nitrogen management in agriculture. This approach targets different forms of reactive nitrogen at the same time. Participants evaluated measures and best practices effective at reducing, for example, ammonia and nitric oxide emissions into air, nitrate leaching into water, and emissions of the greenhouse gas nitrous oxide.

The goal of integrated sustainable management is a dramatic reduction in overall nitrogen pollution, not shifting the pollution problem from water to air (e.g. nitrate to nitrous oxide), or vice versa. The integrat-ed approach should also take into account a broader range of connected environmental issues, such as biodiversity and animal welfare.

This new guidance document will fill a gap in the information currently available, by showing how to simultaneously and cost-effectively address several policy objectives, regarding air, water, soil, climate change, and ecosystems. The target audience in-cludes national governments, regulators, advisory bodies, and farmers.

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Towards guidance on integrated sustainable nitrogen management

This session was chaired by Mr François Wakenhut, Head of the Clean Air Unit (DG Environment), with a scene-setting TFRN presentation by Dr Clare Howard, of the Centre for Ecology & Hydrology (CEH), and a global overview from Professor Mark Sutton, of CEH and INMS (International Nitrogen Management System). Presentations by Ms Liisa Pietola, Head of Environmental Affairs, Central Union of Agricultural Producers and Forest Owners in Finland on behalf of COPA-COGECA, and Mr Jannes Maes, President of the European Council of Young Farmers, provided an agricultural sector perspective. A discussion followed.

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The guidance document will set out the main recommendations and principles for improved nitrogen management in agriculture. It will explain the synergies, co-benefits and trade-offs associated with integrated nitrogen management, and assess the effectiveness of each measure for mitigating the impacts of different nitrogen compounds.

To achieve this integrated approach, it is necessary to understand the underlying principles that explain how each meas-ure works. For instance, the underlying principle of fitting solid covers on liquid manure tanks is that ammonia is vola-tile, so reducing access to air reduces its loss to the atmosphere. Defining a set of interlocking principles facilitates a systems perspective. This helps answer questions like: will this measure reduce both ammonia and nitrates?

The integrated approach will therefore en-able an assessment of nitrogen-reduction measures in terms of positive co-bene-fits or negative side-effects, for example on ecosystems and biodiversity, climate change mitigation, or animal welfare.

Although some costs are recovered through subsidies, it is mainly farmers who pay to implement nitrogen pollut-ant-reduction measures; with limited possibility of recovering those costs by increasing prices.

Therefore, representatives of European farmers’ organisations requested in the workshop that the guidance document provides concrete best practice measures that are also cost-effective and applica-ble to the daily realities of farming. The measures should take into account lo-cal conditions, and the climate from the Mediterranean to northern Europe. Ideal-ly, there should be a range of measures

that can be adapted and prioritised to farm-specific conditions.

Measures may also be technically correct but impractical or expensive for farmers to implement, such as a 200% dilution of manure with water that lowers emissions but increases spraying costs. The prac-ticality of measures and farmer invest-ments should be considered.

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Policyoverview The contributors to the workshop’s policy context panel were Mr François Wakenhut, Head of the Clean Air Unit, Ms Claudia Olázabal, Head of the Land Use and Management Unit, Ms Bettina Doeser, Head of the Clean Water Unit (DG Environment), and Mr Isidro Campos, Policy Officer from DG Agriculture and Rural Development. DG Climate Action and DG Research and Innovation are also involved in the development of the new guidance document. This reflects the relevance of integrated sustainable nitrogen management to several EU policy areas, particularly air quality, water quality and nitrates, climate change, biodiversity, and the circular economy.

Air qualityEU air quality is improving. For example, between 1990 and 2015 emissions of nitrogen oxides decreased by 56%. However, signif-icant air pollution challenges remain. Air pollution is responsible for around 400 000 premature deaths and €24 billion in terms of direct costs, including €3 billion in lost crops per year. Almost 95% of harmful ammonia emissions originate from agriculture, mainly from livestock farming.

At EU level, three areas of legislation address air pollutants. The Ambient Air Quality Directive set maximum concentration levels for several air pollutants, including particulate matter (PM10 and PM2.5) and nitrogen dioxide. The National Emission Ceilings Direc-tive establishes reduction commitments for five pollutants (ammo-nia, sulphur dioxide, nitrogen oxides, volatile organic compounds, PM2.5); for example, an ammonia reduction of 19% by 2030. In addition, source-specific emission standards are set in several di-rectives, such as the Industrial Emissions Directive, with specific Best Available Technique conclusions of relevance for large-scale intensive farming of pigs and poultry.

Water qualityThe Water Framework Directive provides the overall context for addressing pressures on EU water bodies. The aim is to achieve Good Water Status, by 2027 at the latest. However, only 40% of surface water bodies are today in this Good Status. Eutrophication limits are exceeded in 63% of the ecosystems.

Under the Water Framework Directive, River Basin Management Plans cover the entire land area of the EU. These include Pro-grammes of Measures requiring Member States to address the problems identified in their river basins. They can do this through basic measures under existing legislation (e.g. Urban Waste Water Treatment Directive, Nitrates Directive, Birds and Habitats direc-tives); additional basic measures, including cost recovery, safe-guarding drinking water, and controls over abstraction and hy-dro-morphological alterations (e.g. dams and canals); or through supplementary measures defined by Member States, which can be funded under the Common Agricultural Policy.

NitratesThe Nitrates Directive, an integral part of the Water Framework Di-rective, aims to reduce water pollution from agricultural sources. It requires EU Member States to monitor and identify waters polluted by nitrates or at risk of pollution if no action is taken.

Member States designate farmland where water is draining into those waters as Nitrate Vulnerable Zones. Mandatory Action Pro-grammes are implemented in these zones, with subsequent re-porting on their effectiveness. Measures implemented include peri-ods when fertilisers are prohibited, and the construction of storage facilities for manure. Some Member States apply the Action Pro-grammes over their entire territory.

The Common Agricultural PolicyAnnex III of the Regulation on the new Common Agricultural Poli-cy 2021-2027 calls for Member States to establish a system for monitoring nutrients, within the framework of the Good Agricultur-al and Environmental Conditions. The aim is to facilitate a sustain-able use of fertilisers, reduce emissions, optimise farm incomes, and boost the digitisation of the agricultural sector.

Members States can develop their own tools, modify existing ones, or adopt the Farm Sustainability Tool for Nutrients (FaST), which is being developed with Commission support. FaST will provide a level-playing field for European farmers, filling a gap for an easy-to-use digital tool for nutrient advice, especially for small- and medium-sized farms.

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Break-out sessions

Participants were divided into four break-out sessions, armed with draft chapters of the guidance document.

The groups discussed:

1. Principles of integrated sustainable nitrogen management;

2. Livestock feeding/housing and manure processing and storage;

3. Fertiliser and manure application methods; and

4. Land use and landscape management.

Classification tables:Each break-out group ranked the mitigation potential of a set of nitrogen management measures (rows) for each type of nitrogen (columns: NH3, N2O, NO, NO2, NO3, N2, overall N loss). Each case was assigned a UNECE category:

• Category 1 is proven and backed by data;• Category 2 is somewhat problematic but can be used with additional information; • Category 3 is unlikely to be practical but can be used with additional data.

A question mark denotes uncertainty. Arrows could be used to indicate magnitude and direction of effects, while additional columns could include notes, costs, nitrogen removal efficiency, co-benefits and trade-offs, or underlying principles.

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Principles of integrated sustainable nitrogen managementThis break-out session was chaired by Professor Oene Oenema with the help of rapporteur Dr Wilfried Winiwarter. It focused on the dimensions, principles and tools for integrated sustainable nitrogen management. The draft document provided the basis for systematic discussion of the multiple issues related to integration.

Integrated approaches make use of dif-ferent dimensions of integration. This session considered five dimensions: ver-tical integration (linking cause and ef-fect); horizontal integration (combining different forms and sources of nitrogen); interaction with other elements and com-pounds (e.g. phosphorus, sulphur dioxide); multiple stakeholder involvement; and re-gional integration (e.g. harmonisation of policies across the EU or UNECE regions).

Session participants agreed on the defi-nition of a set of fundamental principles for sustainable nitrogen cycling, and a more detailed set of principles of inte-grated sustainable nitrogen management specifically for agriculture. These basic principles represent fundamental truths and laws, and explain why pollution-re-ducing measures are effective. The topics discussed in this session therefore aim to provide the framework and connectivity for the whole guidance document.

The first 6 of 16 draft principles of integrated sustainable nitrogen management in agriculture:

1. The purpose is to avoid air and water pollution while at the same time safeguarding productivity and nitrogen use efficiency;

2. Various actors play different roles in nitrogen management;

3. The main nitrogen loss pathways are (i) ammonia volatilisation, (ii) leaching of nitrate to groundwater, (iii) overland flow of nitrogen forms to surface waters,

and (iv) nitrification-denitrification processes combined with gaseous emissions of nitrogen oxides, nitrous oxide and di-nitrogen;

4. Reducing one form of nitrogen pollution risks increasing other forms of nitrogen pollution;

5. Nitrogen input-output balance is a main indicator of nitrogen management;

6. Matching nitrogen inputs to livestock and crop needs offers opportunities to reduce all forms of nitrogen loss, and can improve economic performance at the same time.

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Break-out session 1

Achieving integrated sustainable nitrogen management requires a set of tools. On a pathway from problem identification to-wards implementing solutions, a first step could be systems analysis, nitrogen bal-ances and integrated assessment model-ling. Communication in general, and stake-holder dialogue specifically, as well as best management practices will facilitate the move to effective practice.

Topics discussed in other breakout sessions may also be regarded as tools, particular-ly the classification tables for measures to generalise the guidance for integrated nitrogen management in agriculture. Oth-er tools relate to capacity building, access to innovation, education and training, net-working and partnerships.

Discussion focused on holistic approach-es to air-water-soil systems; reactive nitrogen interactions with carbon of im-portance to pollution-reduction and cli-mate action synergies; soil health; social aspects including stakeholder empower-ment and rural communities; and food waste as an essential element in circular economy considerations.

Recommendations on integrated sustainable nitrogen management for the guidance document:

• Refocus and sharpen the individual principles of nitrogen management in agriculture;

• Add an overarching introduction, use this chapter as ‘glue’ for the whole document, and make references to other chapters regarding principles and tools;

• Base integrated sustainable nitrogen management policy on the defined dimensions, principles and tools;

• Introduce sustainable nitrogen management measures stepwise, starting with measures e.g. in the annexes of the EU Nitrates Directive and UNECE Air Convention;

• Involve multiple stakeholders, not just farmers, along the whole food production-consumption chain.

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Livestock housing/feedingand manure processing and storageThis session was chaired by Professor Barbara Amon, with Professor Lars Jensen as rapporteur. The group considered the stages of integrated sustainable nitrogen management from animal feeding and housing to the treatment of manure for field application or recycling (e.g. as biogas); and the links between stages along the nitrogen management chain.

The main principle for livestock feed-ing is to optimise crude protein intake to reduce nitrogen loss to the environ-ment, especially via ammonia emissions from urine/faeces. There are important differences between feeding systems for dairy cattle, beef cattle, pigs and poultry, though the same general principles may apply. Some measures reduce emissions, but may not be practical due to increased costs (e.g. artificial amino acids for pigs).

For housing, it is important to keep as much nitrogen in the system as possible. House cooling to reduce emissions is a key method, also for animal welfare reasons. However, cooling slurry in warmer climates is not always economically feasible and re-quires a lot of energy, which conflicts with climate action objectives.

Slurry removal from the animal house is a central measure. However, its efficiency depends on reducing indoor temperature and timing removal to reduce methane emissions. Surface cleaning is only effec-tive if thorough, otherwise it also increases methane. Reducing manure surface has a positive effect, but there is a trade-off with animal welfare. Improved floor types and bedding material can reduce emissions, but bedding requires further assessment.

Key recommendations on livestock feeding for the guidance document:

• Adjust diet to animal performance, adapt crude protein content, optimise amino acid composition, and improve nitrogen retention;

• Dairy cattle: consider methane emissions, give priority to conversion of roughage to high-value products, and adapt to site-specific conditions;

• Pigs: phase feeding according to age or weight.

Recommendations on livestock housing:

• Implement low-emission housing systems (e.g. reduced emitting surfaces, reduced air flow over soiled surfaces, reduced temperature, optimised ventilation);

• Regular removal of slurry to outside storage;

• Provide guidance on pros and cons of slurry versus manure along the nitrogen management chain.

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Break-out session 2

Manure management is a continu-um from generation by livestock to land spreading. The main messages are to re-tain as much nitrogen in the system as possible and to maximise nitrogen use from manure. Session participants not-ed that costs of manure treatment must provide sufficient benefits to be justified. It should also be noted that farmers will need to take into account the nitrogen that remains in the manure that is spread on fields. For this reason, nitrogen loss-es during processing and storage must be measured. Poor manure management also increases production of the green-house gas methane.

Measures for manure treatment were grouped under physical (separation), bio-logical (aeration, composting, anaerobic digestion, wetland construction), chemical (zeolite and clay adsorbents, slurry acidi-fication), and advanced processing (nitrifi-cation, denitrification). Participants noted

the difference between simple treatments that can be taken stepwise on individual farms, and advanced processes that com-bine several types of treatment.

As the draft chapter focused on ammonia emission abatement, replicating previous guidance, participants concluded that more focus should be placed on greenhouse gas-es and nitrate leaching, even though data is often lacking. The integrated approach should also be flexible, as there is no “one-size-fits-all” solution.

Recommendations for manure storage and processing:

• Establish secure manure and slurry storage tanks outside the barn to

stop leakage;

• Cover manure and slurry to prevent emissions to air;

• Optimise manure treatment: reduce slurry dry matter content to reduce ammonia emissions, increase ammonium content to minimise

nitrate losses to groundwater, and lower pH so more ammonia is converted to ammonium.

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Nitrogen inputs are essential for improv-ing crop yields and quality, but the nitro-gen unused by crops can have negative environmental impacts. To date, the em-phasis has been on individual nitrogen loss pathways, especially ammonia to the air and nutrient leaching. However, around 1-2 % of the world’s energy is expended to make inorganic fertilisers, while fertilisation causes emissions of the greenhouse gas nitrous oxide. Therefore, the goal is to jointly address nitrogen pol-lution and climate policy objectives.

The integrated approach starts with the twin underlying principles of reducing ni-trogen application rates and increasing nitrogen uptake efficiency by the crop, to reduce overall nitrogen losses to the environment without compromising crop yield or quality.

Field application of inorganic fertilisers and manureThis break-out session was chaired by Professor Thomas Misselbrook, with Dr Shabtai Bittman as rapporteur. It focused on principles and measures of inorganic and organic fertiliser application, with the aim of reducing or preventing pollution from nutrients, ensuring sustainable nutrient use, and achieving a balanced fertilisation.

The session participants discussed, among other things, the challenges of quanti-fying trade-offs and large uncertainties; general guidance versus context-specific recommendations; the quantification of costs and benefits; and the FaST tool and other developments in new technologies, especially precision spreaders.

Participants acknowledged that improv-ing soil health is a key requirement (e.g. avoiding soil compression), as is linking the nitrogen and carbon cycles to inte-grate farm-level advice on nitrogen pol-lution and climate change objectives. Dis-cussions also focused on optimal grazing levels, and trade-offs in terms of farming practices and animal welfare.

The four key ways of applying nitrogen to reduce losses to the environment are:

a) a) in a form that crops can readily take up;

b) b) at the time when the crop most needs it;

c) at a rate required by the crop that is also economic and sustainable; and

d) in the place it is needed, under the soil surface near the roots.

These are combined in integrated approaches, along with consider-ations of water, pests and diseases, and other factors.

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Recommendations for policy-makers:

• Integrated nutrient planning at farm, sectoral and regional levels;

• Minimise applications to high-risk zones (e.g. near sensitive habitats,

drainage basins);

• Integrate nutrients from recycling of organic residues into agriculture;

• Identify cost-effective mitigation measures;

• Provide technical advice and guidance to farmers

on best practices for nitrogen use.

Break-out session 3

Recommendations for farmers:

• Integrated farm-scale nutrient management planning taking into account all nitrogen sources;

• Implementation of precision measures to increase nitrogen use efficiency;

• Use of appropriate fertiliser products, incorporating inhibitors

as appropriate;

• Use of low-emission slurry spreading technologies;

• Rapid incorporation of ammonia-rich organic

soil amendments.

They evaluated 20 measures in a classifi-cation table. In addition to the key meth-ods already mentioned, these included using urease and nitrification inhibitors, slow-release fertilisers, drip fertigation, slurry injection or dilution, and deep placement to reduce direct run-off. These mainly target ammonia emissions, but can also reduce emissions of nitrous ox-ide and nitric oxide (e.g. urease inhibitors).

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Land use and landscape managementThis session was chaired by Professor Tommy Dalgaard with Dr Klaus Butterbach-Bahl as rapporteur.

The discussions refined and extended the draft guidance. It was noted that nitrogen losses from agriculture can be minimised but likely not eliminated, because there will always be some leaching through soils or direct run-off to water bodies.

Integrated sustainable nitrogen man-agement can extend beyond farms into the wider landscape. This offers addi-tional opportunities for mitigating nutri-ent losses from agriculture, especially in areas with intensive farming or in nutri-ent-pollution hotspots. Landscape-level management practices can be cheaper to implement, as they occur outside of food production areas. However, they should not be seen as replacements for measures at source on farms.

The group considered landscape proper-ties, such as topography, soils, underlying geology and water flows. These influence

nitrogen fluxes, and can be used to target land use management to break nitrogen cascades at the landscape level.

The main challenge is harmonising the needs of integrated nitrogen management, to achieve the multiple goals of clean air, clean water, biodiversity protection, and reduced greenhouse gas emissions.

Landscape-level measures were ana-lysed in terms of their underlying princi-ples. For example, wetland construction increases nitrogen conversion to bio-mass. Agroforestry, hedgerow and tree planting increase nitrogen removal from

air and water, while set-aside areas and buffer zones adjacent to water courses intercept nitrates in run-off.

Measures to reduce nitrogen pollution can help protect vital ecosystem servic-es, including water filtration to achieve clean water. Measures involving habitat restoration often have biodiversity pro-tection as a key driver, and they also en-hance carbon sequestration, mitigating against climate change.

However, the classification table of meas-ures revealed many question marks, as more knowledge is needed about land-

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Break-out session 4

Recommendations forthe guidance document:

• Explore trade-offs with other sectors to best exploit the landscape approach for targeting nitrogen pollution;

• A better definition of landscape is needed for this purpose, with respect to water systems, natural and semi-natural habitats, and agricultural land;

• Use incentives, legislation and governance for

better Implementation of measures;

• Go beyond farm nitrogen balance towards landscape-level nitrogen budgets (e.g. water catchment areas);

• Aim for smart landscape management, taking into account drainage, nutrient hotspots, bioenergy etc.,

to achieve multiple policy objectives.

scape-level management, such as the carrying capacity of the landscape for ni-trogen. Nitrogen inputs from agriculture are known, but much less is known about where it leaves the system. One sugges-tion was a toolbox linking agricultural and natural landscape nitrogen balances.

Further discussion focused on smart landscape-level farming, the placement of crops depending on landscape proper-ties, incorporating nitrogen-fixing plants, and considering renewable energy in these schemes.

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Conclusion:

The way forwardThe workshop was part of an ongoing process towards a new UNECE guidance document on integrated sustainable nitrogen management in agriculture.

Previous guidance has focused on one part of the problem at a time, either focusing on air pollution or water pollution but not both together. This new guidance takes the next step.

It shows how a joined-up approach to ni-trogen management can exploit substan-tial synergies and co-benefits. This will enable the development of economical-ly-feasible solutions that tackle multiple problems caused by multiple forms of re-active nitrogen in the environment, solv-ing air, water and soil pollution problems, and mitigating climate change impacts.

In agriculture, integrated sustainable nitrogen management can exploit syn-ergies all along the nitrogen cycle, to si-multaneously reduce pollution problems caused by ammonia, nitrate, and nitrous oxide. Managing nutrients correctly is also important for livestock and crop productivity, and for reducing costs and supporting food security.

The draft guidance chapters will be fur-ther developed based on the feedback during the workshop, for presentation to and discussion in the UNECE Air Conven-tion decision-making bodies during 2020. The aim is to have an adopted guidance document ready and published in 2021.

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