Written evidence from the Sustainable Nitrogen Alliance (NIT0007)

Sustainable Nitrogen Alliance evidence for the ECC Nitrogen inquiry

Summary

1. Initially founded by the Soil Association, Plantlife and WWF in 2021, the Sustainable Nitrogen Alliance is a coalition of environmental, human health and animal welfare organisations and scientists looking to communicate and cooperate with the Government to reduce the multitude of damaging impacts resulting from excessive nitrogen use and pollution - both in the UK and through the UK’s global footprint.
2. Nitrogen cannot be treated in siloes. Previous governments have tended to end-of-pipe solutions without consideration of wider nitrogen impacts, which has resulted in pollution swapping. We are advocating for an integrated, system-thinking approach across government to reducing wasted nitrogen resources, which requires cross-government working to achieve policy co-benefits and to minimise trade-offs. Promoting a circular economy is a prime opportunity to implement a systems-wide approach to reducing nitrogen pollution and incentivising more sustainable nitrogen use. However, in addition to advancing waste recycling initiatives, the government must implement measures to curb the prevalence of harmful livestock systems that generate excessive waste.
3. This government could be the first to maximise the co-benefits that are achieved from designing policies in context of the wider nitrogen system, by introducing a Nitrogen Strategy to direct a cross-government approach to reduce pollution beyond that achieved by incremental approaches and blinkered by sectoral siloes. To do so requires a Nitrogen Balance Sheet, to account for nitrogen flows across the economy and the environment, and identify primary actions to reduce pollution and recycle nitrogen as a valuable resource.
4. Building on international experience this will require targeted regulation and incentivised voluntary schemes, investment in new technologies, as well as extended and improved versions of existing schemes such as Catchment Sensitive Farming.
5. Finally, we recommend that the Government introduces nitrogen budgets at the farm, catchment and national scale with shared stakeholder responsibility to progressively bring nitrogen pollution under control.

General

1.       What are the main sources of nitrogen pollution in the UK? How and why have these changed over time?

1. The main sources of nitrogen pollution are agriculture, industry and energy combustion, wastewater and food waste.
2. The industrial revolution was brought about by the ability to produce energy using fossil fuels. Since the expansion of the fossil fuel industry, the nitrogen cycle has become imbalanced by the pollutants these processes emit. The main sectors relating to these emissions include transport, industry, commercial and residential combustion. Historically, these were the greatest sources of emissions, but progress has been made in the transport sector through the use of catalytic converters and the expansion of the green vehicle fleet. Similarly, the scaling of renewable energy sources has alleviated the reliance by industry on fossil fuel sources, while by-product emissions of nitrous oxide occurring during the production of nitric acid have been effectively abated in the UK since the 2010s.[1]
3. After the Second World War, the Green Revolution and the invention of the Haber-Bosch process brought about synthetic, fossil-fuel derived nitrogen fertilisers. Farmers were encouraged by the government to use synthetic nitrogen fertiliser to increase yields and meet food demand. By the turn of the century, humans had more than doubled the amount of reactive nitrogen in the world, largely through agricultural practices and management.[2] But there has been an increasing awareness of the environmental and social impact of excess and inefficient fertiliser and manure use and of combustion-related air pollution.
4. Agricultural pathways of nitrogen loss include inefficient synthetic nitrogen fertiliser use, livestock and manure management, and some fossil fuel use. The agricultural sector contributes 71% of the UK’s nitrous oxide emissions,[3] 31% of which is from synthetic nitrogen fertiliser.[4] Areas with high concentrations of industrialised indoor-reared livestock have the biggest nitrogen surplus. The number of intensive cattle, pigs and poultry units has grown 12% in the last 10 years, with minimal abatement measures in place. Intensive cattle units are not covered by environmental permitting regulations as pigs and poultry are, so measures to monitor and mitigate emissions are not currently in place. It is estimated that 60% of nitrate pollution in the water environment comes from agriculture and the relative contribution of agricultural pollution to water quality pressures is increasing.[5]
5. One third of nitrogen imported to the UK is soya from animal feed for intensive livestock systems.5 Soya is imported from South America where it is linked to the destruction of tropical forests and the wildlife that lives in them.
6. Nitrogen is lost during wastewater treatment, and presents a prime opportunity for nitrogen recovery. The wastewater sector accounts for 3-7% of anthropogenic nitrous oxide emissions, with emissions on the rise.[6]
7. The UK produces the largest amount of food waste in Europe, generating 25 million tonnes of GHG emissions annually. The greenhouse gas emissions associated with the 9.5 million tonnes of food waste from households is estimated to be around 36 million tonnes of carbon dioxide equivalent. This annual waste has an approximate cost of £19 billion and has associated emissions of 36 million tonnes of carbon dioxide equivalent. In addition to greenhouse gas emissions, food waste represents a loss of valuable nitrogen resources.

2.       How could nitrogen pollution be mitigated from relevant sectors, how effective are these approaches, and are there any trade-offs?

8. There is much that could be done to mitigate pollution, with some promising approaches that need to be scaled up. A range of policy measures will be required to do so, including long-term strategic regulation, appropriate incentives and financial support, and well verified training and advice. In this answer, we have outlined a range of sector-specific solutions to reducing nitrogen pollution, but recommend that the government uses a Nitrogen Strategy to direct a cross-government approach to reduce pollution beyond that achieved by incremental approaches and blinkered by sectoral siloes. The manner in which sector-specific policies should be implemented can only be efficiently driven by a system-wide strategy which accounts for “pollution swapping”, where an action to reduce losses in one form inadvertently increases losses in another form.
9. Agriculture

9.1.            Tackling sources of agricultural nitrogen emissions to the air in the UK will require measures affecting livestock, agricultural soils, combustion sources and farm machinery. In turn measures tackling agricultural soil emissions will need to address leaching, synthetic fertiliser, organic manure, atmospheric deposition, crop residues, cultivation of soils, nitrogen-fixing crops and wastes.

9.2.            The agricultural sector demonstrates an average nitrogen use efficiency (NUE) of around 55% for crop production,[7] and only 6-37% for animal products.[8] When considering a full-lifecycle approach, from the creation of reactive nitrogen to its intended use for crops, this decreases to 11% with the remaining 89% lost to the environment in varying  forms. In addition to an environmental and social cost, this represents the loss of a valuable resource for farmers. Farming at the Maximum Sustainable Output with reduced inputs increases returns ranging on average from 10% to 45% by sector.[9] Mitigating nitrogen pollution and reducing synthetic fertiliser demand through improving NUE of fertiliser use can be done by:

9.2.1.            Precision/targeted application of fertilisers (4Rs: right fertiliser source, rate, time and placement)

9.2.2.            Accompanying fertiliser with biostimulants

9.2.3.            Urease inhibitors

9.3.            Opportunities for reducing nitrogen pollution from fertilisers include replacing synthetic with the use of natural sources of nitrogen, such as nitrogen-fixing clover or herbal leys, improving soil organic matter and soil filtration, and adopting systems less reliant on inputs.[10] These practices are often more cost-effective and better evidenced than technological solutions being relied on (anaerobic digestion), and some are even cost saving for farmers (reducing fertiliser costs), and have feasible roll-out rates (subject to sufficient advice and support by government and relevant agencies). A tradeoff is that systems less reliant on synthetic fertiliser may have lower productivity per hectare but are more profitable per hectare, due to reduced inputs. Alongside dietary change as recommended in the Seventh Carbon Budget, reducing the amount of land used to grow feed for intensive livestock systems will allow for lower, less extractive forms of farming while freeing up land for nature, house building, and energy production.[11]

9.4.            Organic manure is commonly used as a fertiliser and presents an opportunity for recycling nutrients. It comes in multiple forms: farmyard manure; slurry; compost; and green manure, each with individual benefits and risks of environmental impacts. Management of organic manure (slurry in particular) has great nitrogen mitigation potential, with opportunities for better storage infrastructure and application techniques.[12] Suggestions include:

9.4.1.            Better slurry and manure storage (capacity and infrastructure type) e.g. six-month slurry storage capacity; impermeable slurry store covers. Barriers to implementing slurry stores include the significant financial investment required. One option could be to support communal slurry stores for clusters of small-scale farmers to share the investment. However, the government should introduce other policy measures to ensure systems are not pushed to the maximum, as could be the case with increased storage.

9.4.2.            Better slurry and manure spreading techniques e.g. low emission spreading application technology. The Clean Air Strategy 2019 committed to make slurry/digestate spreading using low-emission spreading equipment (trailing shoe or trailing hose or injection) a requirement by 2025.[13] This commitment has not been met.

9.5.            Farmyard manure should be prioritised as a fertiliser type because of its ability to build soil organic matter and hold more nitrogen in the soil than slurry, which has higher rates of leaching. It also provides advantages over organic manures imported onto the farm - for example, the contaminant risks associated with sewage sludge use, such as PFAS and microplastics, which are virtually impossible to remove from the soil. Mixed farming, which rotates livestock and crops across fields, allows the cycling of nutrients across the farm through a diversification of crops. Diversification increases climate resilience and food security, while mixed systems provide many socioeconomic, cultural and environmental benefits.[14] Nonetheless, when determining the appropriate application rate of farmyard manure in a particular area, proximity to protected sites and watercourses should be taken into account.

9.6.            Establishment of riparian buffer strips reduces nitrogen leaching into rivers, with a nitrogen removal efficiency rate of 10-36% depending upon width.[15] This also creates different habitats, creating win-win-wins for nature, climate and farm business resilience as funding can be accessed through Environmental Land Management schemes (ELMs). However, the Government should ensure buffer strips are sufficient widths to provide benefits and avoid trade-offs such as nitrous oxide emissions.[16]

9.7.            Intensive livestock farming is harmful for the environment, human health, animal welfare and the climate. Farmers are often contracted to and controlled by large agribusinesses and international corporations, with little profit for the farmer. Regulations to control intensive livestock systems are currently not fit for purpose.[17]

9.7.1.            The scope of environmental permitting regulations must be widened to include dairy and beef systems. Bringing them inside the regulations is a prime opportunity for controlling these high-nitrogen polluting systems as requirements include limitations to stocking densities and on-site waste management plans. It is notable that Defra attributes the fall in ammonia emissions from the pig and poultry sectors as being in a large part due to the Pollution Prevention and Control Act (1999) making all new intensive pig and poultry installations subject to ammonia controls through permitting. This supports the case for action to manage polluting cattle systems in the same manner.

9.7.2.            However, the threshold for the size of the pig and poultry system included in environmental permitting regulations is far too high, with environmental damage taking place at a much lower level of stock than is currently regulated. In addition, the cumulative effect of multiple sheds is unaccounted for in the current permitting regime, meaning the cumulative impact of nutrients on the catchment is not considered. Criteria based on local ecological context should apply to permits to prevent environmental damage, particularly in vulnerable areas. Requiring nutrient budgeting and well-implemented nutrient management plans (extending the current requirement from farms within Nitrate Vulnerable Zones (NVZs) to all farms, starting with big indoor units) would reduce nutrient loading from intensive livestock farming in catchments where the capacity is exceeded or watercourses are in unfavourable condition.

9.8.            A reduction in the number of livestock is required to mitigate climate change, deliver nature recovery and nutrient mitigation. This reduction must be supported through schemes that provide just diversification opportunities for farmers and agricultural workers. This reduction must also be supported by ambitious public good schemes which pay for the climate and nature benefits unlocked by reduced stocking levels, particularly in the uplands. Higher tier ELMs play a key role in this, but must be urgently scaled up. A reduction in livestock numbers is needed for both outdoor grazing cattle and intensive, indoor-reared animals. The latter should be prioritised, due to the many ecological and social impacts of these systems.

10. Transport

10.1.            While much progress has been made in reducing nitrogen oxides emissions from vehicles, there is more that could be done. The following measures require the government to commit to a long-term vision - only in signalling long-term ambitions will the transport industry ramp up investment into zero emission vehicles. We welcome the phasing out of the sale of new petrol and diesel cars from 2030, as the Secretary of State for Transport committed to earlier in 2025. However, progress to support vehicle-free societies, such as 15-minute cities, and the reduction in prices of public transport will encourage and incentivise urban  populations to live without cars.

10.2.            We recommend the Government invests in speeding up the modal shift towards a zero emission vehicle fleet.11 An unavoidable trade-off is the cost of infrastructure required to support such a shift, such as widespread upscaling of electric charging points. Overnight street charging proves a more convenient, easier and cheaper way to charge than relying on rapid hubs or destination charging.

10.3.            New developments should have sustainable transport options built into development plans, including concepts such as:

10.3.1.            15 minute cities - ensuring new developments have sufficient infrastructure so that cars are not required.

10.3.2.            Increased number of bicycle lanes/routes for vehicle-free travel.

10.4.            Improving public transport

10.4.1.            Public transport fares have increased 38% in ten years. Reducing the price of public transport and/or providing cheaper bundles / maximum spend for inner-city travel would reduce vehicles on the road in urban areas.

10.4.2.            Making public transport more reliable will increase public use.

10.5.            Extend low emission zones in cities, with restrictions on the types of vehicles that can enter i.e. highly polluting lorries.

11. Wastewater

11.1.            Nitrous oxide emissions from wastewater are increasing. We recommend that nitrogen pollution could be mitigated by investment in nitrogen recovery technology and for water companies to pay farmers to go above and beyond regulations to reduce nutrient waste.

11.1.1.            Tradeoffs include increased costs for taxpayers from the use of grey infrastructure to strip nitrates from wastewater. Nature-based solutions as blue and green infrastructure, such as riparian buffers, should be prioritised in the first instance.

11.2.            Source separation i.e. commercial and residential wastewater streams to better target removal of pollutants.

12. Food waste

12.1.            Food waste is also a growing source of nitrous oxide emissions, with some win-win solutions that would provide cost-savings for households and reduce wasted food.

12.2.            The first measure introduced should be to require all local councils to introduce food recycling, with appropriate financial support from the central government.

12.3.            The Government should support education campaigns to raise public awareness of the cost savings from reducing household food waste. One estimate calculates potential cost savings at £60 a month by reducing the amount of food that is thrown away.

12.4.            The Government should implement mandatory, public food waste reporting across all large food businesses, to include waste in supply chains.

12.5.            The Government should encourage the use of food waste as a fertiliser, with the right safeguards in place to ensure contaminants are removed.

12.6.            The Government could investigate the potential for allowing a greater portion of food waste to be fed to pigs. The 2001 Foot and Mouth disease outbreak led to very strict controls on what types of food waste could be fed to livestock. In recent years, however, the pressing need to improve the environmental and financial performance of the UK pig sector have led to growing calls to look again at the use of swill, as Japan and South Korea have done to huge success through a well-regulated industry that safely treats retail, catering and manufacturing food waste.

12.6.1.            More than three quarters of the carbon footprint of British pork relates to feed, partly from the emissions associated with nitrogen fertiliser use but also because of the massive amounts of CO2 released by habitat destruction associated with overseas soya production. Replacing some of this grain and soya with food waste would go some way to tackling these problems -  sourcing just 10% of conventional European pig and poultry feed from food waste would reduce habitat destruction and greenhouse gas emissions associated with feed production by more than 30% and 15% respectively. Another paper calculated that feeding swill to pigs would reduce the land use footprint of the European pig sector by more than 20%, freeing up an amount of grain equivalent to that consumed by 70 million EU citizens, while at the same time cutting the area of overseas land needed for soya by 268,000 hectares.[18]

12.6.2.            Re-legalising swill could also bring benefits for farm profitability. In Japan and South Korea, swill is typically only half the price of conventional feed. While the more variable nutritional quality of swill does mean that growth rates are often somewhat lower, the overall impact on profitability still tends to be a very positive one. And this is before the bonus of price premiums are considered: in Japan, for instance, pork produced from pigs fed on food waste is sold as ‘yoghurt pig’, where it fetches a higher price because consumers are willing to pay for its environmental benefits.

13. Energy combustion

13.1.            We recommend that the Government re-introduces a legal requirement to prepare, implement and consult on a detailed plan to meet its emission reduction commitments under the National Emission Ceiling Regulations 2018. New legally binding emission reduction commitments for NOx and NH3 that apply from 2040-2049 and 2050 onwards should be set under the National Emission Ceilings Regulations 2018 to drive further reductions in these emissions.

13.2.            Align air quality targets with the World Health Organisation guidelines.

13.2.1.            The annual limit value for NO2 under the Air Quality Standards Regulations 2010 should be changed from 40 µg/m3 to 10 µg/m3, aligning this with the current WHO guideline.

13.2.2.            The deadline for meeting the 10 µg/m3 PM2.5 annual mean concentration target under the Environment Act 2021 should be brought forward from 2040 to 2030. This should form a stepping stone towards reducing annual mean concentrations of PM2.5 to the current WHO guideline level of 5 µg/m3 in the shortest time possible.

13.3.            Further develop the government’s programmes for domestic energy efficiency and switching from fossil fuel-based heating to technologies that are at least less reliant on gas and oil, such as heat exchangers.

3.       What solutions and technologies are available to increase nitrogen reuse and recycling, including in agriculture, waste, wastewater, industry, and transport sectors?

14. Agriculture and diets

14.1.            Upscaling more sustainable sources of nitrogen fertiliser that cycle nitrogen through the soil, such as legumes, increases nitrogen recycling as they fix nitrogen from the air. Examples of companion crops include cover crops which provide soil cover during winter and provide a natural source of nitrogen. Intercropping is another form of companion cropping which provides nutrients naturally, while also enabling the farmer to diversify their income by growing two crops at once. The Innovative Farmers Network has held trials on intercropping and identified the following benefits:

14.1.1.            Improving soil health and resilience to stress

14.1.2.            Increasing biodiversity

14.1.3.            Maximising land productivity

14.1.4.            Reducing the need for synthetic fertilisers (when legumes are planted)

14.1.5.            Reducing the carbon footprint of arable farming

14.2.            Extensive, mixed farming systems using rotational cropping to fertilise soils with livestock herds, recycling manure as fertiliser.

14.2.1.            Legumes can be used in livestock systems to raise the content of improved pastures and alleviate the use of synthetic fertilisers.

15. Recovering nitrogen from waste (agriculture and wastewater)

15.1.            Source separation could potentially abate 60% of N2O emissions from wastewater while recovering nutrients for agriculture purposes.[19] However, there needs to be regulation and monitoring in place to ensure contaminants, such as PFAS, pathogens and microplastics, are removed. The Government should develop and implement measures to ensure harmful and persistent contaminants are removed before biosolids can be applied to agricultural land.

15.2.            Recovery of manure to capture nutrients from waste. In Europe, there is a drive to upscale ‘RENURE’ (Recovered Nitrogen from manure) as a vehicle to reduce reliance on fertiliser and natural gas from Russia. Trials of similar products have also been undertaken in the UK, although at least one company found biosolids to be a more economically viable source. RENURE is the use of ammonium salts recovered from manure with the benefits cited as being low-carbon recycling of nutrients. Under the Nitrates Directive, there is a 170 kg/ha/year limit on organic fertilisers applied to land, while synthetic fertiliser limits can be set at significantly higher levels by Member States (and UK) if supported by scientific data. Therefore, there is ambition for these products to be excluded from the 170 kg limit. There is a trade-off here, in that if organic manures were applied more widely (using best practice techniques) in place of synthetic fertilisers, that would benefit soil health by adding carbon, as well as nutrients, and would also enhance soil biology. In practice, the concentration of cattle farming in the West and arable in the East, makes transportation of organic manures more costly, in addition to having less certainty and controllability around the nutrient content being  applied. As a result, RENURE does offer a solution to some of the problems associated with synthetic fertilisers, even though agroecological and regenerative approaches or simpler technologies like separators to generate wet and (more transportable) dry fractions would be the environmental option of choice.  The development of recovered nutrients must not be used to prop up the industrialisation of livestock farming, which in absolute terms, increases the environmental impacts of agriculture (including reactive nitrogen). Instead the root causes of nutrient pollution should be addressed, and a significant reduction in the number of livestock is needed.

15.3.            Anaerobic digesters (AD) are a similar, but more established technology generating concentrated ‘digestate’ from food or animal waste, reducing the volume by 5-10%. However, their use is associated with several negative externalities that are not currently accounted for. To ensure the sustainable use of AD, it is essential to impose restrictions on the types of inputs used in the process. For example, maize, a common feedstock used as a co-digestate, requires nitrogen fertiliser and contributes to issues like leaching, run-off and soil degradation. It is recognised as a ‘high risk crop’ particularly because it is harvested late (end of September or early October), by which time heavy rainfall may drive pollution and it is also too late to sow a cover crop to protect the soil over winter.[20] Where maize is grown, regulations must be strengthened to ensure it is not cultivated along riverbanks or on steep hillsides, where pollution is more likely. Intercropping maize with winter wheat can also mitigate run-off and leaching risks, as well as attracting Sustainable Farming Incentive ‘companion crop’ payments. Furthermore, the government should avoid using AD as a waste management solution for intensive farming operations, as digestate is nutrient-rich and may exacerbate the environmental impact of such systems. Use of digestate as fertilizer should follow sustainable management practices of slurry to reduce ammonia emissions.[21]

15.4.            AD is a growing source of ammonia, increasing 2588 per cent since 2009, and leakages of other gases such as methane. Climate emissions of digestate storage, transportation and utilisation are higher than synthetic fertiliser utilisation on field.[22]

4.       What future developments could further increase nitrogen pollution, and how could those risks be reduced?

16. Green ammonia fertiliser is often hailed as the future of fertiliser use, allowing big agriculture to carry on farming above the soil’s natural productive potential.[23] While it would reduce the nitrous oxide emissions associated with synthetic fertiliser production, green fertiliser will continue to produce pollution during application. There are great risks in relying on a solution that is not yet viable as a route to Net Zero.
17. Using ammonia fuel for shipping has potential to be a much larger source of nitrogen pollution than it is currently, with significant implications for port air quality and wider environmental, climate and human health impacts. It is estimated that by 2070, ammonia production for energy will be an order of magnitude larger than the current production of the fertiliser industry, with reactive nitrogen emissions comparable to the current cumulative emissions from agriculture, industry and energy sectors.[24]
18. The Government has proposed to ease the planning process for expanding intensive livestock facilities where this would  improve animal welfare. However, evidence suggests developers seek to increase absolute poultry numbers, with   improved welfare part of the rationale for their expansion (e.g., recent applications in  Shropshire and South Wales), with data showing units often exceed permitted stocking densities. Developers already have the power to meet welfare standards within existing frameworks. Any relaxation of planning policy for intensive livestock units is a significant risk to nitrogen pollution. The government must adopt the recommendations of the Environmental Audit Committee in 2022, and adopt a presumption against granting planning permission for new intensive livestock units where nutrient budgets are exceeded.
19. Increased development (house building and infrastructure), if not accompanied by appropriate safeguards to effectively implement nutrient neutrality measures in a way that does not regress environmental protections. Agricultural livestock systems, particularly large cattle units, should be managed in a similar way where nutrients are controlled in catchments with low ecological health.
20. Biofuels hold significant potential for increased nitrogen pollution. Achieving CO2 mitigation of 0.7 (± 0.3) GtCO2e per year through the use of biofuels would necessitate an additional 21–42 million tonnes of nitrogen being applied annually to croplands.[25] Crops like maize require nitrogen and other fertilisers and generate a high risk of erosion and pollution, as described above, yet are increasingly grown as feedstock for anaerobic digesters.
     

Impacts

1.     What are the ecological impacts of nitrogen pollution in the UK and what implications do these have for national environmental and net zero targets?

21. Nitrous oxide is the third most prevalent greenhouse gas, yet the Seventh Carbon Budget does not go far enough to address the contribution that nitrogen makes to climate change. The agricultural sector contributes significantly to both global nitrous oxide and methane emissions, accounting for 69% and 48%, respectively.[26] Since nitrous oxide is 273 times more potent than carbon dioxide, we think this should be more clearly addressed in the pathways. This would have wider benefits in addition to mitigating climate change and stratospheric ozone depletion since the sustainable nitrogen fertiliser practices required would reduce all nitrogen losses to the environment, which would have the co-benefit of reducing the nitrogen impact on the resilience of ecosystems to climatic events through reduced species abundance – a less degraded and more diverse ecosystem has a greater capacity to endure climatic events and global heating.[27]
22. Water system impacts

22.1.            Excess nutrients in rivers drive algae growth, which blocks out the sunlight and depletes dissolved oxygen levels. Ecological dead zones occur as a result.

22.2.            Only 16% of England’s waters are in good ecological health, with detrimental effects being driven by the input of agricultural nutrients, including nitrogen, to the environment alongside sewage discharges.[28] 5164 km of rivers, and 96 lakes/reservoirs in England are formally designated as affected by freshwater eutrophication.27

22.3.            In eutrophic standing freshwaters in particular, nitrogen can be a factor limiting waterbody health; 55% of England’s lakes currently fail WFD standards for Nitrogen. Reducing both nitrogen and phosphorus loads is often needed to restore ecological quality in the water environment.

23. Vegetative impacts

23.1.            Atmospheric nitrogen deposition, predominantly from livestock sources and fertiliser use, depletes species abundance and diversity by creating conditions preferable to ‘generalist’ species that prefer highly-fertile soils. ‘Specialist’ species, such as wildflowers, lichens and mosses cannot thrive in such conditions and are consequently outcompeted by the generalists. England has lost 97% of its wildflower meadows due to the use of fertiliser on pastures.

23.2.            In England, 99% of sensitive habitats are overloaded with nitrogen,[29] causing biodiversity loss and species shifts, which drives a decline in the health of Sites of Special Scientific Interest (SSSIs) and irreplaceable habitats such as ancient woodlands. Many SSSIs are the last home for species at risk of extinction in England.

23.3.            High levels of airborne nitrogen pollution can be linked (among other factors) to the presence of acute oak decline, a disease fatal to oak trees in just four to six years.[30] Nitrogen pollution weakens many plants and trees, increasing their vulnerability to pests and diseases.

23.4.            Nitrogen deposition occurs not only in environments surrounding the source, but also in locations great distances away. For example, the nitrogen critical load is exceeded in 95% of the area of woodlands in the UK (managed and unmanaged),29 even in Atlantic rainforests on the west coast of Wales, far from intensive nitrogen sources such as transport and intensive agriculture. Atmospheric nitrogen deposition is also increasing carbon loss from peat bogs and about 15% of woodland soil in England and Wales is nitrogen saturated, which can increase nitrate leaching from soils and associated aluminium toxicity to the plant roots.[31] Nitrogen deposition also increases the prevalence of acid rain by increasing the nitrogen oxides in the atmosphere and ammonium deposition which can acidify ecosystems when mineralized.

2.     What are the public health impacts of nitrogen pollution and how are these accounted for in current government plans and targets?

24. Nitrous oxide is the most prevalent ozone depleting substance and is not controlled under the Montreal Protocol. It is the most significant threat to the stratospheric ozone layer,[32] and if current emissions trends continue we can expect to return to a level of peak ozone depletion by 2050 (Global N2O Assessment). Stratospheric ozone depletion increases the cases of skin cancer and cataracts.24
25. Nitrogen, in the forms of nitrogen oxides (NOx) and ammonia, combines with other pollutants in the atmosphere to form particulate matter (PM2.5). Ammonia emissions from agriculture contribute to a quarter of fine particulate matter pollution in London, and 32% in Birmingham.[33] Analysis from the European Environment Agency indicates that in 2019, PM2.5 was responsible for more than 33,000 deaths annually in the UK. It has been estimated that a global halving of agricultural emissions could reduce the mortality attributed to PM2.5 by approximately 250,000 globally and by 52,000 across Europe.[34]
26. NOx is also a precursor of tropospheric ozone that has health impacts, with a short term association to increased mortality.[35]
27. Nitrate may pose a risk to human health in water bodies used for drinking water abstraction. In groundwater, 69% of water bodies are at risk of failing and 37% are classed at poor chemical status (or have rising trends) due to nitrate. Nearly 30% of groundwater used for public water supply must be blended or treated to remove nitrate and meet drinking water standards; a process which can be costly and energy-intensive, with the cost passed onto the consumer.27

3.     What are the economic impacts of nitrogen pollution and current nitrogen-mitigation policies, for the public, farmers and other stakeholders?

28. The cost to the UK of agricultural ammonia emissions impacts was projected at over £700 million per year in 2020 with estimates ranging between £580 million and £16.5 bn.[36] The cost of overall nitrogen waste was calculated as £2.5 bn - equal to the 2025-2026 Defra farming budget.7

Government policy and regulation

1. How effective is existing policy at regulating and reducing nitrogen pollution? How could they be improved? Are there gaps?

29. Existing policy to regulate and reduce nitrogen pollution is piecemeal, with issues being tackled independently across different sectors and government departments, leading to pollution swapping. Previous governments relied upon end-of-pipe reactive solutions which put weight behind technological fixes, with the assumption that they would be enough to move the dial. However, incremental changes are not sufficient to meet environmental, climate and health targets. Achieving the substantial reductions in nitrogen pollution necessary to restore ecosystems, reverse biodiversity loss, and mitigate harm to human health and the climate will require comprehensive, system-wide change.
30. To avoid unintended consequences and maximise the co-benefits of policy measures, the government should implement a comprehensive Nitrogen Strategy that addresses the nitrogen system as a whole. Utilising a Nitrogen Balance Sheet would allow for informed policy decisions, helping prioritise actions, avoid unintended consequences and clearly identify potential trade-offs across departments.
31. Reducing pollution from agriculture in particular requires a package of measures, including advice, regulation and incentives. Nutrient management has an element of complexity in that different policy levers manoeuvre stakeholders to different ends. For example, some farm types manage fertiliser extremely efficiently due to the proportion of costs spent on inputs, such as intensive arable farms. However, smaller-scale livestock farms may find less value from investing resources into nutrient management planning, especially when manure—their primary fertiliser—is often seen as a waste product due to its abundance. Policy must be developed to reflect this nuance in farming types - not only arable versus livestock, but large and intensive versus small scale and extensive. Policy levers will influence farmers differently.

31.1.            The slow raising of awareness around Farming Rules for Water regulations is a prime example of why regulation cannot be implemented without adequate supporting advice and awareness campaigns. Agencies currently enforcing these regulations are sharing advice after pollution events have been identified, rather than before to prevent them. This is a symptom of the scaled back funding received by regulating agencies over the last decade, and the risk-based approach to enforcement employed as a result.

31.2.            There is a specific gap in policy regarding the granting of new environmental permits for intensive livestock units. When such a permit is granted, detailed information is required and an inspection regime is put in place for the permit holder for the waste and nutrient management practices onsite. However, no such detail is required for waste produced by intensive livestock units and sent offsite to be spread on local land - even though this is now common practice. There is no clear process within the permitting system to check that destination farms have adequate storage and a deficiency of nitrogen such that they can accommodate manure / slurry and be compliant with the Farming Rules for Water and rules for NVZs, where these apply. Thus, permits are being granted - which allow large increases in nitrate production - without due diligence and chain of custody for the waste produced. This regulation gap would be solved with a redesign of agricultural permits, requiring full accountability for waste sent offsite. Catchment-level budgets could also help - ensuring that no more waste can be added to a catchment where the budget is already exceeded.

31.3.            Regulation can provide conditions for investment and growth. Such an example is the use of catchment level budgeting to regulate the amount of nitrogen (nutrients) applied to land based on the maximum ecological level of nitrogen loading. Enforced by nitrogen budgets at the catchment level, which share responsibility between relevant stakeholders to reduce nutrient loading, budgets would ensure that farmers are applying below the regulated limit, with catchment-specific measures and targeted advice. Nitrogen budgets also encourage farms to shift from yields per ha to profit per ha by improving NUE and reducing wasted resources.

31.4.            Catchment Sensitive Farming (CSF) is a useful initiative for sharing education and awareness of diffuse pollution management methods. Upscaling this to a nationwide advisory service could provide compliance support, with training focused on soil testing and nutrient management to reduce pollution to the air and water systems. The remit of CSF should be expanded to consider broader environmental impacts and emphasise nature-based solutions. Further, CSF could support farmer-to-farmer networks for sharing innovative, nature-friendly practices, such as the Innovative Farmers programme by the Soil Association.

31.5.            The Government will not be able to meet targets without targeting incentives to encourage the right type of farming in the right places. ELMs should incentivise nature friendly farming methods which operate in accordance with a farm’s Maximum Sustainable Output, which help optimise nitrogen inputs and stocking densities. However, incentives should not be used where regulation requires the same actions.

32. But policy must go further. It is imperative that the government appropriately links the processes relating to land use, food production and nature. The planning process needs to be connected to the Net Zero pathway and the Land Use Framework (which should cover the whole of the UK), with the ELMs schemes and the Environment Improvement Plan.
33. Sensitive political topics, such as diets, will need to be addressed. Reducing nitrogen content in diets will require reducing meat consumption in high-meat diets to the national dietary intake recommended of 70g per day. However, the solution does not lie in shifting diets to other meats (e.g. chicken, which is largely intensively produced), as that also comes with significant problems, such as those witnessed around the River Wye. Shifting towards more sustainable sources of protein i.e. less but better meat by reducing the intake of processed meat will create more demand for legumes and pulses and reduce the associated fertiliser and land used to grow animal feed. Dietary changes are critical to increase the proportion of protein sources derived from plant-based options like legumes and pulses, while reducing reliance on processed meat from intensive farming systems.
34. There is growing evidence that the public are supportive of more interventionist measures to reduce meat and dairy consumption, with a recent research panel showing 90% of panel members supporting strong regulation of large food companies if necessary.[37]
35. Currently, the British food system is vulnerable to international geopolitical and climatic shocks. Not only is a large proportion of food on our shelves sourced overseas, but farmers relying on synthetic fertilisers are at risk of political unrest because Russia produces the gas - and in increasing proportions - the fertiliser. The less reliant British farmers are on synthetic fertiliser, the more resilient and self-sufficient our food system can be.
36. Recent shifts in policy approaches could also bring challenges to tackling nitrogen pollution. For example, despite recognition that the large spending bill for meeting environmental obligations cannot be met by the public purse alone, and that private finance will need to play an increasing role in delivering against ambitions, restrictions upon the water sector (designed to ensure regulatory compliance and protection for customers from inefficient spend) could have the unintended consequence of limiting the sector’s ability or appetite to work jointly with the farming sector on reducing water pollution.
37. Specific policy gaps were identified in an evaluation of the ability of existing policies to achieve nitrogen-reductions within national statutory targets and international commitments, commissioned by the Sustainable Nitrogen Alliance.[38] Rather than listing here, we suggest the Committee reviews the gaps listed in the report. In addition to these, the Alliance has identified the following policy gaps:
38. Agriculture

38.1.            Lifting the Environmental Act targets in line with the Kunming-Montreal Global Biodiversity Framework targets, specifically Target 7 to halve nutrient waste by 2030.

38.2.            Linking policy incentives and regulation to environmental targets e.g. spatial targeting of Sustainable Farming Incentives to achieve outcomes linked to the Environmental Act targets.

38.3.            Absence of policies to reduce the import of nitrogen embedded in commodities, such as soya.

38.4.            Regulatory standards for nitrogen pollution have regressed in recent years, with new gaps created by the end of cross compliance in January 2024 with no replacement. This included the loss of the longstanding Good Agricultural and Environmental Condition 1: Establishment of buffer strips along water courses, which mandated the establishment of buffer strips along water courses outside NVZs.[39]

38.5.            The changing approach to enforcement and historic budget cuts in responsible authorities. Whilst we appreciate the enforcement resources have risen again this decade, it is important that monitoring and evaluation of the outcomes of the ‘advice-led’ approach to enforcement are published, and that this informs the enforcement strategy.

38.6.            The lack of a transparent pathway from Defra and its counterparts in other nations setting out how the voluntary schemes will be used to meet current binding and more aspirational environmental objectives. For example, the Farming and Countryside Programme has no outcome-based objective to measure ELMs’ contribution to species abundance.

38.7.            The relatively low budget and share of overall effort allocated to advice. A National Farm Advice service would plug the gaps where knowledge is lacking e.g. nutrient management.[40]

38.8.            Elements of poor value for money in ELMs and missed opportunity to maximise the additionality ELMs’ limited public funding delivers., For example, nutrient management plans in the SFI have been very popular, but do not require farmers to make any management changes. This poor value is exacerbated by the fact that many industry schemes already require members to produce nutrient management plans, including LEAF and Red Tractor Fresh Produce. However, other voluntary schemes do not have the same requirements. Therefore, there is a need to ensure a level playing field and prevent double funding, by integrating low-value plan actions into the regulatory baseline over time as part of an advertised transition, to ensure reductions keep pace with targets. Nutrient management plans (CNUM1) on croplands would be most suitable for this approach, as nutrient planning in these systems is likely to be financially beneficial for farmers. This allows limited budget to be better directed to fund more ambitious, outcomes-focussed nutrient management actions.

38.9.            Lack of ambitious mandatory sustainability targets for public procurement with agroecological targets (e.g. 20% Organic certified).

39. Food waste

39.1.            A UK-wide mandatory food waste reduction target.

39.2.            Mandatory requirements for sectoral food waste reduction.

39.3.            Require and fund all local councils to introduce household food waste recycling through Simpler Recycling.

39.4.            Support a campaign to educate the public on the cost savings from reducing food waste.

39.5.            Implement mandatory food waste reporting across all large food businesses. The Government consultation found that 99% of respondents, including the majority of businesses, supported the introduction of mandating the policy. This could be done through an SI under the Environment Act targets.

39.6.            Mandate a requirement for all food producers to report pre-farm gate food waste which has been estimated at 3.3 million tonnes per year, in the UK alone.

39.7.            Recycling of food waste as a fertiliser, with no biodegradable waste to incineration or landfill.

2. How effective is monitoring and enforcement of nitrogen-related regulations?

40. There are a number of agricultural regulations that are in place but incredibly ineffective due to a lack of awareness and low levels of enforcement.

40.1.            The Farming Rules for Water Regulations were not well publicised when they were introduced. As such, there’s a low level of awareness that compliance is required. Enforcement is largely focused on a risk-based approach, with only 4% of farms visited.

40.2.            NVZs currently cover 55% of the UK, and have done so since 2017. Nitrate reductions to the environment within NVZs are estimated to be between 2% and 7%.[41]

3. Does current policy incentivise the capture and reuse of ‘waste’ nitrogen and, if not, what policy changes could support greater reuse of nitrogen?

41. Nitrogen is prime for a circular economy approach, with reductions in ‘new’ reactive nitrogen entering the system (e.g. from fossil fuels, artificial fertilisers, diets and imported animal feed) alongside more efficient use and recovery of nutrients to reduce nitrogen pollution (e.g. livestock waste and food waste).

41.1.            A number of policy levers are readily available to support a circular nitrogen economy across a range of sectors. Recovering nitrogen from waste presents an opportunity to generate new bioeconomy markets by converting recovered nitrogen into marketable fertiliser products, while nitrogen inputs could be significantly reduced across supply chains, both domestically and internationally, through improved NUE and more sustainable nitrogen sources.

41.2.            However, the commercial agricultural sector is inherently linear. The Government needs to shift to systems that incentivise and improve the ease of recycling nutrients.

41.3.            Preliminary policies to improving nitrogen circularity should be focused on the following:

41.3.1.            Improving NUE and a shift away from synthetic fertiliser use to more circular systems, like mixed farming or using food waste as fertiliser.

41.3.2.            Reducing food waste.

41.3.3.            Recovery of nitrates from wastewater.

41.4.            Reusing sewage sludge should be a useful source of nitrogen however, there are problems from pollution by chemicals, such as PFAS and microplastics. As it is damaging to the environment, and potentially damaging to human health, the Government should regulate the use of biosolids to ensure the water companies are responsible for removing contaminants before it is used on soils.

4. What are the pros and cons of taking a more holistic approach to nitrogen management in policy, and what opportunities to do so exist?

42. An approach siloed by sectors is not sufficient to meet targets because incremental adjustments will not significantly reduce nitrogen pollution, and will likely lead to pollution swapping. System-wide change is required across sectors including agriculture, food supply chains and diets, planning and development, and infrastructure and transport, with push-pull mechanisms driving change to both demand and supply. When introducing regulation, the Government must commit to a long-term vision, which will drive innovation in industry and technology.
43. Without taking a system-wide view when designing nitrogen policies, unintended consequences are likely. Nitrogen is leaky and has a tendency to ‘pollution swap’, so measures to reduce one form of nitrogen must not be designed in isolation of other forms. Ammonia for example, cannot be treated independently from GHGs, especially emissions/sequestration of CO2 in soils and vegetation, and emissions of N2O that also are intrinsically connected with the same substrates (fertilisers and manure) that are key in the release of ammonia.
44. Care should also be taken to consider wider environmental and welfare outcomes - particularly progress to Net Zero, alongside impacts on human health, animal welfare, biodiversity and water pollution. For example, focusing on carbon alone drives a tendency to intensification. If we continue to assess the sustainability of different foods and farming systems through the lens of emissions intensity (i.e. how much pollution per kg of product) we risk missing the bigger picture. The Netherlands is a prime example of this: a country lauded for its sustainability because intensification has driven down the emissions intensity of production. But now the drive to intensify has breached critical nitrogen thresholds more locally. In response, we need to assess sustainability more holistically, that includes a proper consideration of impacts at a national/system level.
45. The way land is currently used is majorly ineffective, with increasing demands for energy, food and housing - something has to change. Land use must be linked to multiple policy targets. Ineffective use of land should be reduced, such as land used for intensive livestock feed, whereas land that contributes to nature goals should be safeguarded. Half of agricultural land is used to feed intensive livestock, with the rest of the feed coming from imports of soya - driving deforestation abroad. Scaling mixed farming systems which rotate livestock and crops through the system would increase multifunctionality of land, while progressing towards nature, air quality and climate targets. Integrating livestock in the system provides an alternative nutrient source to synthetic fertiliser, which when managed properly, builds soil organic matter and increases resilience to climatic shocks.[42]
46. Moving to healthier diets with less and better patterns of meat consumption can tackle nitrogen pollution by reducing consumption of nitrogen-intensive foods while creating more space for crop and livestock systems which are more multifunctional. Food resilience and productivity does not have to be compromised by bringing more nature into those spaces.
47. While many agroecological practices (e.g. forage legumes in pasture) hold the potential to reduce nitrogen losses, as does a broader shift to agroecology, alongside an accompanying shift in diets. Care will need to be taken as significant nitrogen losses can still occur from mispractice, for example, when temporary leys are ploughed into the soil before the following cropping phase, significant nitrogen mineralisation can occur. However, this tradeoff could be mitigated by upscaling agroecology with a training and advice network to ensure the right practices are being implemented in the right places.

Best practice

1.     What examples of best practice relating to monitoring, regulation or management of nitrogen should be considered, including international examples?

48. The UK has appointed focal points to the UNEP Nitrogen Working Group and should look to develop a voluntary National Action Plan for sustainable nitrogen management. A first example of such a Plan was published by Japan last year.
49. There are also counterfactual examples of what has not worked well, in terms of regulatory approaches, which explores a range of international case studies of voluntary schemes, and shows that they were largely ineffective.[43]
50. The Netherlands and Denmark have made significant progress in reducing nitrogen losses to the environment in recent decades using regulations and incentives, such as financially subsidised voluntary schemes.

This submission from the Sustainable Nitrogen Alliance is supported by the following organisations:

●       Soil Association

●       WWF

●       Plantlife

●       RSPB

●       Woodland Trust

●       The Wildlife Trusts

●       Compassion in World Farming

●       Sustain

●       Sustainable Food Trusts

●       Environmental Investigation Agency

●       Wildlife and Countryside Link

06/03/2025

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