A new online calculator and guidance has been developed to help farmers and others to design woodlands to capture airborne ammonia and so reduce air pollution.
Scientists from the Centre for Ecology & Hydrology worked with Forest Research to develop the free online tool and guidance for users as part of research funded by the Scottish Environment Protection Agency.
Agriculture is the main source of ammonia emissions in the UK, with the majority coming from animal manure and fertilisers.
Ammonia can lead to excess reactive nitrogen levels in sensitive habitats, causing a decline in the biodiversity of lichens, mosses and other flora. It can also lead to acidification of soils, and combines with other pollutants to produce particulate matter pollution, which is harmful to human health.
By following the advice in the guidance, farmers, regulators and planning authorities can optimise tree planting to recapture ammonia around animal housing, which is a key source of ammonia emissions. The calculator estimates the percentage of ammonia that will be recaptured by different planting options, over a set time period – up to 50 years.
The guidance advises which tree species will thrive in different parts of the UK, what distance to plant trees from animal housing, and in what configuration. There is also information to help with the incorporation and use of existing woodlands.
Dr Bill Bealey, an ecologist at the Centre for Ecology & Hydrology, said: “Trees are particularly effective scavengers of air pollutants like ammonia. They recapture the pollutant in the tree canopy and on to the leaves, and they also help disperse the ammonia plume which reduces impacts of nitrogen pollution on nearby sensitive habitats.
“Farmers who use trees to mitigate ammonia can look to a long-term range of benefits. New canopies can improve animal welfare by providing animals with shade and protection from aerial predators. They can also provide screening around animal housing units, to soften the look of buildings and minimise visibility impacts on the landscape.”
Dr Elena Vanguelova, a soil sustainability expert from Forest Research, said: “Tree shelters are an agroforestry technique that have benefits for farmers and society as a whole.
“The capture of carbon and nitrogen by additional planting will play a role in helping the UK achieve its greenhouse gas emission reduction targets.
“Our calculator and guidance provide farmers and landowners with the information they need to use nature’s best nitrogen mops to mitigate the ammonia produced by animal housing units while protecting soils, waters and the wider environment.”
The calculator is available free online at www.farmtreestoair.ceh.ac.uk
Notes to editors
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Sources of ammonia (NH3) emissions are predominantly from agricultural sources like livestock manure and slurry, and fertiliser application to crops. Ammonia is a highly soluble and reactive gas containing nitrogen (N) which can readily deposit (called N deposition) from the atmosphere to vegetation and the soil. N deposition to sensitive habitats damage plant communities that have evolved on nutrient-poor soils (e.g. bogs, heathlands and some woodlands). A number of studies have shown that nitrogen deposition is an important driver for reducing species richness (Field et al., 2014; Stevens et al., 2010). Recent data (2013-2015) on nitrogen limits set for habitats show that on average >60% of the area of sensitive habitats in the UK exceeded their nitrogen limits.
Ammonia can also cause soil acidification as ammonia in the soil oxidises to nitrate, with toxic chemicals such as aluminium becoming available, while elements vital for plant growth decrease. Together with nitrates, these toxic compounds can also leach into freshwaters where they are toxic for fish and other aquatic life. Nitrate leaching can cause the pollution of ground and drinking water.
Ammonia can also react in the atmosphere with other pollutants to form particles and lead to poor air quality and human health impacts. There are air quality targets for the levels of particles in the air we breathe, and reducing ammonia emissions could help meet these targets.
The tool covers England, Wales and Scotland. It is currently not available for Northern Ireland, although there are plans to extend it soon.
About the Centre for Ecology & Hydrology
The Centre for Ecology & Hydrology (CEH) is the UK's Centre of Excellence for integrated research into land and freshwater ecosystems and their interaction with the atmosphere. CEH is part of the Natural Environment Research Council (NERC) and employs more than 450 people at four major sites in England, Scotland and Wales. CEH tackles complex environmental challenges to deliver practicable solutions so that future generations can benefit from a rich and healthy environment.
About the Natural Environment Research Council (NERC)
NERC is the UK's main agency for funding and managing research, training and knowledge exchange in the environmental sciences. Our work covers the full range of atmospheric, Earth, biological, terrestrial and aquatic science, from the deep oceans to the upper atmosphere and from the poles to the equator. We coordinate some of the world's most exciting research projects, tackling major issues such as climate change, environmental influences on human health, the genetic make-up of life on Earth, and much more. NERC is part of UK Research & Innovation, a non-departmental public body funded by a grant-in-aid from the UK government. https://nerc.ukri.org
About Forest Research
Forest Research is an executive agency of the Forestry Commission. It conducts world-class scientific research and technical development relevant to forestry to support and inform the policies for sustainable forest management of all four administrations in the UK. www.forestresearch.gov.uk
About Scottish Environment Protection Agency (SEPA)
SEPA is Scotland’s principal environmental regulator. Our purpose is to deliver environmental protection and improvement (environmental success) in ways that, as far as possible, also create health and wellbeing benefits (social success) and sustainable economic growth (economic success). Our services include: monitoring and reporting on the state of our environment, working with partners to promote sustainable resource use, environmental regulation, providing public warning systems, and responding to environmental emergencies. We help to deliver the Scottish Government’s policy agendas on topics including climate change, zero waste, environmental crime and sustainable flood risk management. www.sepa.org.uk