Improving Air Quality

Poor air quality is one of the biggest risks to the environment and to public health. The Welsh Government’s Clean Air Plan sets out a range of actions to be taken to improve the nation’s air quality. For farming, the focus is on ammonia because it contributes around 85% of Welsh ammonia emissions. The majority of agricultural ammonia emissions are from livestock farming (mainly cattle).

Nitrogen is lost to the air as ammonia from manures and from spreading fertiliser. It builds up in the atmosphere and then falls on to the land, interfering with ecosystems and making it impossible for some species to survive. In low concentrations, ammonia is not harmful to human health. However, it can react with other pollutants to make Particulate Matter, which can get deep into lungs causing health problems for people. Ammonia lost to the air is also nitrogen lost for plant growth, costing farms money.

This tool has been developed to show the actions a typical Welsh farm may be able to take to improve air quality. These actions also bring real business benefits. As well as from fertiliser use, ammonia can be lost whenever slurry or muck is exposed to the air. Because of this, the actions need to be used together to get the full benefits. To learn more about how you could carry these out on your own farm, follow the links at the bottom of each example. This will show you what support is offered by Farming Connect, the Welsh Government and others. Guidance on lowering ammonia emissions is also available in the Code of Good Agricultural Practice.

Please remember that slurry gases can kill. For more information on managing the risks from slurry please read the Health and Safety Executive guidance.

Use our interactive farm to discover ways to improve air quality. Click on the hotspots to learn more

Farm illustration
Background mountains Background buildings Background fields

Improving Air Quality

Air treatment and muck drying

Exhaust air from pig and poultry houses can be treated by acid scrubbers or biotrickling filters to remove the ammonia. These systems are fitted to the outlets of mechanically ventilated housing and are very effective where the animals are kept indoors all the time, with some reducing ammonia emissions in the exhaust air by up to 90%. The technology is widely used in new housing and can also be retrofitted to older buildings.

It is also important to keep poultry muck and litter dry because, when it becomes wet, much more ammonia is lost to the atmosphere. It can be kept dry by using a belt drying system. This lowers ammonia emissions by 30%. The muck should be stored under a water-proof cover.

Other benefits

  • They also have the benefit of reducing smells, which is important if it’s near where people live
  • Drier poultry muck will have a higher fertiliser value

Support

Farming Connect could help you improve the efficiency and sustainability of your business. Discover how Farming Connect can assist you with improving skills, accessing advice and be inspired by new and innovative ideas from the demonstration network and the Knowledge Exchange Hub.

Air treatment and muck drying
Background buildings

Improving Air Quality

Efficient use of protein in the diet

All animals eat nitrogen through the protein in their feed. More than half of the protein animals take in through their food is lost as nitrogen in their muck. These losses can be lowered by matching (as closely as possible) the protein content of the animal’s diet to its needs. This simple change can lower ammonia emissions by around 10%.

Research1 has found that dietary crude protein levels for lactating dairy cows can be lowered to 14% with little to no loss in milk yield or fertility. A project at the Institute of Biological, Environmental & Rural Sciences (IBERS) has also found no overall effect on growth from lowering crude protein, from about 14% to about 11.5%, in heifer diets. This has a big benefit in managing ammonia emissions on the farm because the losses at other stages (at housing, storage and spreading) becomes much less but it is important to speak to your nutritionist before making any big changes to cow diets.

Other benefits

  • Well-balanced, lower protein rations mean lower input costs
  • It can also potentially improve fertility (more studies are being carried out)

Support

Farming Connect could help you improve the efficiency and sustainability of your business. Discover how Farming Connect can assist you with improving skills, accessing advice and be inspired by new and innovative ideas from the demonstration network and the Knowledge Exchange Hub.

  1. https://www.cambridge.org/core/journals/animal/article/abs/reducing-dietary-protein-in-dairy-cow-diets-implications-for-nitrogen-utilization-milk-production-welfare-and-fertility/8357F0CB36F0C31DBCC13D33619B42B7
Efficient use of protein in the diet

Improving Air Quality

Extending the grazing season

When cattle are grazing they produce much less ammonia emissions because their urine is quickly absorbed in to the ground. By extending grazing in to the autumn and spring, less slurry is produced by the animals when they are housed over winter. With grass being the cheapest feed for producing milk, this approach can help cut costs. However, extending grazing in the autumn and spring needs to be carefully managed to avoid soil compaction and damage to the sward, which can lead to water pollution.

With more grass grown, rotational grazing can extend the grazing season but it may not be suitable for all farms. It needs careful planning and good grassland management. This needs to take into account the farm’s soil type, topography and infrastructure and needs to be flexible to adapt to changes in the weather. Multi-species leys can help because they have a longer growing season and offer other benefits like lowering the need to buy in fertiliser.

Other benefits

  • Producing more milk from forage lowers costs
  • AHDB estimates £1.25 a cow a day can be saved by cattle being at grass rather than being housed
  • The deeper roots of multi species leys means they improve soil structure and grow for longer in dry periods

Support

Farming Connect could help you improve the efficiency and sustainability of your business. Discover how Farming Connect can assist you with improving skills, accessing advice and be inspired by new and innovative ideas from the demonstration network and the Knowledge Exchange Hub.

Extending the grazing season

Improving Air Quality

Regular scraping

The sooner slurry reaches the store from livestock areas the less it is exposed to air, with 15% less ammonia lost at housing. Cubicle and feed passages should be designed to drain quickly and be scraped as frequently as possible. To get the slurry to the store as soon as possible, it needs to be scraped from the cow cubicle house, ideally at least once every two hours. More frequent scraping means slurry has less chance to build up and cause problems with lameness.

Although it is a relatively new concept in the UK, it is possible to design cubicle houses to lower ammonia emissions by keeping any contact between muck and urine to a minimum. This involves either a sloped floor with a gutter for urine or a grooved floor with specially designed ‘toothed’ automatic scrapers. Both allow urine to drain away quickly.

Other benefits

  • Clean and dry floors will improve foot health
  • Specially designed grooved floors lower emissions, give good grip and help create a dry, clean environment for the cows

Support

Farming Connect could help you improve the efficiency and sustainability of your business. Discover how Farming Connect can assist you with improving skills, accessing advice and be inspired by new and innovative ideas from the demonstration network and the Knowledge Exchange Hub.

Regular scraping

Improving Air Quality

Washing the collection yard

Concrete yards and passages contaminated with slurry emit ammonia. Collecting yards, livestock handling areas and parlours should be scraped and washed down as soon as possible after use. By washing these areas straight after milking has finished, the amount of ammonia lost can be lowered by around 70%. This may not be practical on every farm but it is a simple and relatively inexpensive way of lowering emissions. It needs be part of a dirty / clean water management system and could need extra storage for slurry or dirty water.

Other benefits

  • Clean and dry floors will improve foot health

Support

Farming Connect could help you improve the efficiency and sustainability of your business. Discover how Farming Connect can assist you with improving skills, accessing advice and be inspired by new and innovative ideas from the demonstration network and the Knowledge Exchange Hub.

Washing the collection yard

Improving Air Quality

Covering the slurry store

Putting a cover on a slurry store or lagoon can have a big impact by stopping ammonia escaping to the atmosphere. Watertight covers also have the benefit of stopping rain getting in to the store. Most covers include vents, which stop a build-up of methane, and also need to allow access for the slurry to be stirred.

There are three main types of covers. A tight lid, roof or a tent-type structure is very effective, reducing ammonia emissions at storage by about 80%. Floating sheets are also available and are probably the best option for smaller earth-banked lagoons. They are quite effective, reducing ammonia emissions at storage by around 50%. Slurry bags are a relatively new technology but have been widely used in the Netherlands for 30 years and are very effective, reducing ammonia emissions at storage by around 95%. If you are thinking of installing a bag, you can find out what the planning requirements are by contacting your local planning authority.

Other benefits

  • Less rainwater entering the store lowers the overall amount of storage needed as well as lowering the costs of spreading
  • Less Nitrogen is lost from the slurry, increasing its fertiliser value
  • Less smell

Support

Farming Connect could help you improve the efficiency and sustainability of your business. Discover how Farming Connect can assist you with improving skills, accessing advice and be inspired by new and innovative ideas from the demonstration network and the Knowledge Exchange Hub.

Covering the slurry store

Improving Air Quality

Switching from straight urea fertiliser

Up to 45% of the nitrogen can be lost from urea-based fertilisers. Switching from urea fertiliser to nitrate (or other types of nitrogen) can lower the amount of ammonia lost by 80% for solid fertiliser. Many manufacturers also now supply urea fertiliser with inhibitors (known as protected urea). These delay the urea being broken down and keep the nitrogen in the soil for longer. This stops some of the losses seen in straight urea fertiliser but is still not as effective as nitrate fertiliser is. Although it costs more per kg than straight urea, it can lead to costs savings because less nitrogen is lost as ammonia.

Whichever fertiliser you use, by using a nutrient management plan you can make sure you meet the needs of soil and crop and minimise nutrients lost to the air or water. Spreading bagged fertiliser when the weather and ground conditions are right and using a regularly maintained, calibrated spreader gets the best results. Lowering the need to buy in fertiliser by making use of legumes (like clover) will also improve air quality, save the farm money and lower your carbon footprint.

Other benefits

  • Less nitrogen is lost and so more is available to the crop
  • Protected urea has a lower carbon footprint than ammonium nitrate
  • A simple soil test and nutrient management planning can boost yields and save money

Support

Farming Connect could help you improve the efficiency and sustainability of your business. Discover how Farming Connect can assist you with improving skills, accessing advice and be inspired by new and innovative ideas from the demonstration network and the Knowledge Exchange Hub.

Switching from straight urea fertiliser

Improving Air Quality

Woodlands

Trees and woodlands have the potential to recapture ammonia from animal housing, slurry stores and roaming areas, lowering emissions by 20%. Tree shelterbelts should be downwind (which is ordinarily to the northwest) from the livestock housing or slurry store and need to include a short, dense backstop. The shelterbelt needs to be as wide, or wider, than the building. Trees could also be planted upwind from a slurry store to lower the wind speed over its surface. It is important to get advice before planting to make sure the right trees are placed in right location to get the most benefits.

Other benefits

  • Lowers the farm’s carbon footprint
  • Shade and shelter for animals
  • Can soften the look of buildings to minimise the impact on the landscape
  • Offer habitats to wildlife

Support

Farming Connect could help you improve the efficiency and sustainability of your business. Discover how Farming Connect can assist you with improving skills, accessing advice and be inspired by new and innovative ideas from the demonstration network and the Knowledge Exchange Hub.

Woodlands
Foreground fields

Improving Air Quality

Precision slurry spreading

Up to 80% of the nitrogen in slurry can be lost when using a splash plate. Using shallow injection, trailing shoe or a dribble bar equipment lowers the amount of ammonia lost by placing the slurry directly on or in the soil.

Trailing hoses (dribble bar) and trailing shoes place the slurry / digestate just above (hose) or straight on to (shoe) the soil. Slurry and digestate can also be placed in to the soil using shallow or deep injection (also known as open or closed slots). Closed slot injection is the most effective, lowering emissions by 90% but can also be the most challenging in terms of practicality. Trailing hose or shoe are quicker and cheaper than injection but less effective at lowering ammonia emissions (30-60%).

Whatever the type of precision spreading used, by using a nutrient management plan you can make sure you meet the needs of soil and crop and minimise nutrients lost to the air or water. You can also keep these loses to a minimum by avoiding spreading when the ground is covered in frost or snow and when it’s windy or raining heavily.

Other benefits

  • Work in Ireland1 has shown the value of nitrogen gained can be as high as £12/ha more using a trailing shoe and £19/ha more using open slot injection compared to using a splash plate
  • Precision spreaders spread the slurry more evenly and are not affected by the wind
  • Precision spreading creates less aerosols, which means there is less risk of spreading bovine TB2
  • There is less smell

Support

Farming Connect could help you improve the efficiency and sustainability of your business. Discover how Farming Connect can assist you with improving skills, accessing advice and be inspired by new and innovative ideas from the demonstration network and the Knowledge Exchange Hub.

  1. https://www.teagasc.ie/publications/2020/spreading-the-benefits--low-emission-slurry-spreading-less.php
  2. https://www.daera-ni.gov.uk/projects/133s3-literature-review-potential-role-cattle-slurry-spread-bovine-tuberculosis
Precision slurry spreading
Foreground trees Foreground trees

Improving Air Quality

Poor air quality is one of the biggest risks to the environment and to public health. The Welsh Government’s Clean Air Plan sets out a range of actions to be taken to improve the nation’s air quality. For farming, the focus is on ammonia because it contributes around 85% of Welsh ammonia emissions. The majority of agricultural ammonia emissions are from livestock farming (mainly cattle).

Nitrogen is lost to the air as ammonia from manures and from spreading fertiliser. It builds up in the atmosphere and then falls on to the land, interfering with ecosystems and making it impossible for some species to survive. In low concentrations, ammonia is not harmful to human health. However, it can react with other pollutants to make Particulate Matter, which can get deep into lungs causing health problems for people. Ammonia lost to the air is also nitrogen lost for plant growth, costing farms money.

This tool has been developed to show the actions a typical Welsh farm may be able to take to improve air quality. These actions also bring real business benefits. As well as from fertiliser use, ammonia can be lost whenever slurry or muck is exposed to the air. Because of this, the actions need to be used together to get the full benefits. To learn more about how you could carry these out on your own farm, follow the links at the bottom of each example. This will show you what support is offered by Farming Connect, the Welsh Government and others. Guidance on lowering ammonia emissions is also available in the Code of Good Agricultural Practice.

Please remember that slurry gases can kill. For more information on managing the risks from slurry please read the Health and Safety Executive guidance.