Rick Gould examines the damage caused by ammonia emissions from farming – and how the government plans to bring these emissions down
The government's Clean Air Strategy (CAS) names ammonia as one of five key pollutants targeted for significant emissions reductions by 2030 (the others are oxides of nitrogen, sulphur dioxide, respirable particulate matter and volatile organic compounds). While road transport, power generation from fossil fuels and industrial activities are the main sources of emissions when it comes to these other four pollutants, agriculture is the dominant source of ammonia release.
The nitrogen in ammonia can have a significant impact on habitats that thrive in low-nitrogen soils
The government plans to use a combination of guidance, new legislation and economic support for techniques to reduce ammonia emissions. It has committed to reduce ammonia emissions by 16%, based on 2005 levels. Overall mass ammonia emissions are lower than the emissions of other gaseous pollutants, but the emitted levels have not fallen as quickly. Moreover, the nitrogen in ammonia can have a significant impact on habitats, especially those that thrive in low-nitrogen soils, such as some types of woodland, bogs and moorlands.
A wealth of scientific evidence shows a clear connection between nitrogen deposition and impacts on ecosystems, such as changes in soil chemistry and a loss of species richness. The nitrogen deposition initially affects plants; this, in turn, means a loss of habitats for animals such as insects and birds.
During the past few decades, scientists have developed metrics to characterise the impact of air pollution on ecosystems. One of these is the concept of the 'critical load'; in the case of ammonia, this is the degree of tolerance a habitat has for deposited nitrogen. Well over half the habitats in the UK have exceeded their critical loads for nitrogen: in 2017, for example, Defra reported that, while the proportion of habitats above the critical loads has fallen, at least 62% of habitats exceed their critical loads. When it came to very sensitive habitats, such as calcareous grassland and many types of woodland, Defra reported exceedances of between 80% and 100%.
Under the Habitats Directive, environmental regulators in the European Union must prevent further damage to specific categories of habitat and restore them to a good ecological state. This means reducing ammonia emissions. What are the main sources, and how can they be controlled?
Lessons from abroad
According to Defra, 88% of the UK's ammonia emissions are from agricultural activities, with manure spreading, fertiliser application and livestock housing accounting for three quarters of these emissions. These proportions are typical for the EU. Dairy and beef farming contribute almost half of ammonia emissions, while poultry and pig farming contribute 15% and 7% respectively.
Within Europe, the regulators and agricultural sectors in the Netherlands and Denmark were the first to tackle the challenge of agricultural ammonia emissions; between 1990 and 2016, they succeeded in reducing such emissions by 64% and 40% respectively. This was achieved through a combination of managerial, economic, technical and legislative measures – for example, covering all slurry stores and specifying that all new animal housings must have the means to contain and reduce emissions of ammonia. Altering the ways in which farmers apply fertilisers and manure to fields, as well as changing animal feed formulations, can also significantly reduce emissions.
Both the Netherlands and Denmark have used legislative measures, too; these include permits for all but the smallest farms, with a requirement for fertiliser management plans and a limit on the amount of fertiliser that can be used. Recognising the costs of making such changes, they have, for example, developed incentive schemes or provided grants for some of the techniques that reduce emissions.
Ammonia emissions - The facts
- Ammonia can react with other gases in the atmosphere to form fine particulate matter, after which it can travel long distances
- Ammonia can have a large impact locally, and particularly on habitats sensitive to nitrogen. Well over half of the habitats in the UK are overloaded with nitrogen due to air pollution, especially from ammonia
- In the EU, agriculture contributes about 90% of the total emissions of ammonia, with road transport and industry contributing the rest
- Dairy and beef farming contribute almost 50% of the UK's agricultural emissions of ammonia; poultry farming contributes 15% and pig farming about 7%. Currently, only the largest pig and poultry farms are directly regulated for ammonia pollution
- Intensive farms with capacities for 40,000 chickens, 2,000 turkeys or 750 breeding sows need a Part A environmental permit from a national environmental regulator, and applying Best Available Techniques reduces emissions by approximately 30%
- There are around 1,300 such farms, and they contribute about 5% to the total agricultural emissions of ammonia
- The government intends to reduce ammonia emissions by 16% by 2030, using emissions from 2005 as a baseline.
- There is a growing trend towards much larger farms, especially intensive farming.
The UK's plans
“While larger farms are able to absorb the costs of controls for ammonia emissions, most UK farms are small-to-medium-sized businesses“
The government aims to replicate the successes of the Netherlands and Denmark using a similar approach. Defra has already worked with the agricultural sector to develop guidance, publishing the Code of Good Agricultural Practice (COGAP) for Reducing Ammonia Emissions in 2018.
The national environmental regulators regulate the largest intensive farms under the Industrial Emissions Directive and require controls to reduce ammonia emissions. However, the scope of this Directive only includes the largest pig and poultry farms. In England, for example, these farms contribute about 5% of the total emissions, meaning that most farms are currently unregulated. The government intends to include the dairy and beef sectors within the environmental permitting regime, as well as continuing to work with the agricultural sector to apply managerial, technical and economic measures to reduce emissions.
Meanwhile, the National Farmers Union (NFU), despite being broadly positive about the need to reduce ammonia emissions, is opposed to an extension of the permit regime to cover farms outside the scope of the IED. Instead, the NFU has proposed alternatives such as incentive schemes, which have been successful in Denmark for smaller farms. However, any alternative to permitting would have to be at least as effective at reducing emissions.
The NFU has stated that environmental permitting would impose extra administrative burdens on many farms, as well as large costs for permit applications and the equipment to reduce emissions. This is the heart of the issue – who should pay for the costs of reducing ammonia emissions? While larger farms are able to absorb the costs of controls for ammonia emissions, most UK farms are small-to-medium-sized businesses and may be less able to do so – hence the government's intention to provide economic support.
Tackling the supply chains
According to the European Commission (EC), farmers throughout Europe – especially smaller ones – are often squeezed by powerful buyers in the food supply chain, with supermarkets at the top and several intermediates between them. Supermarkets account for well over half of the retail food market in Europe, and the EC has reported numerous unfair practices among larger buyers in supply chains, meaning that, in the EC's view, primary food producers often get a raw deal. Globalisation and intense competition among supermarkets drives down prices, and the EC cites examples in which these price cuts are passed down the supply chains to farmers.
However, in March, the European Parliament voted to adopt a Directive on combating unfair trading practices in food supply chain business-to-business relationships. While member states may have their own laws and codes of practice against unfair practices, the Directive harmonises and strengthens these. If the UK adopts this Directive, farmers and other smaller food producers will have the legal right to challenge the unfair practices that result in poor returns on food production. More importantly, as sustainability embodies economic and social aspects as well as environmental management, this raises the question as to whether the cost of controlling ammonia emissions should be borne by famers alone, or by everyone who benefits from the food supply-chain, including consumers?
Rick Gould, MIEMA CEnv is a technical advisor at the Environment Agency. He is writing in a personal capacity.
