Challenges
Poor air quality continues to harm public health and the natural environment in Scotland. Progress in improving air quality is both uncertain (due to an inadequate evidence base) and slow (due partly to uncertainty about the efficacy, cost, and consequences of improvement measures).
Ammonia emissions are problematic as they lead to indirect emissions of nitrous oxide when redeposited on soils from the atmosphere; nitrogen deposition leads to soil and water acidification and can affect plant biodiversity. Ammonia also binds with other gases in the atmosphere to form fine particulates which damage health when inhaled. Ammonia emissions from beef production are a significant agricultural contributor to human deaths attributable to poor air quality.
In Scotland, ammonia emissions have only reduced by 16% since the 1970s, with agriculture currently responsible for 92%, and ruminants contributing 52% of ammonia emissions from agriculture. Good practice measures to reduce ammonia emissions from ruminant farming are well established, but uptake is low. This may be due to low public pressure, lack of farmer awareness of the impacts and/or causes, and for economic reasons.
Ammonia emissions have distinct seasonal variations, with high emissions in spring and autumn associated with manure and fertiliser application. Hence, implementing low-cost actions when there is a risk of high ammonia emissions could have a big benefit. Providing farmers with decision support tools to identify sources of ammonia emissions and their effects will raise awareness and help drive the uptake of mitigation actions.
In ruminants, there may be a trade-off between intensively housed systems with lower methane but higher ammonia emissions and extensive systems with higher methane emissions per kilogram of meat or milk, but lower ammonia emissions. It is important to understand these trade-offs to develop management practices that provide a balance between these two gaseous emissions.
New measurement technologies, data products, and modelling concepts are developing at pace. Several low-cost sensor networks are being established in Scotland with a focus on traffic sources and urban exposure. Whilst these can provide information on personal exposure, identification of sources, research into spatial patterns and raise public awareness of air pollution, little work has been done to exploit these new approaches to assess agricultural sources and ecosystem impacts.
Questions
- What tools, apps and/or devices can be developed or tested and validated to monitor site-level or regional ‘hotspot’ air pollution associated with a range of land-based or environmental sectors?
- How do we assess the collective impacts on both target (air quality/climate change) and non-target policies (for example, biodiversity, and ecosystem services)?
- How do we support farmers, land managers and decision-makers to reduce NH3 (ammonia) emissions from farm fertilizers and livestock in Scotland?
Solutions
This project aims to:
- Identify measures to mitigate ammonia emissions from livestock (especially ruminant) farming to develop tools to accelerate the adoption of mitigation measures
- Understand the possible implications of ammonia mitigation for greenhouse gas (GHG) emissions
- Develop tools to demonstrate the impact of ammonia emissions
- Monitor and evaluate new technologies for direct measurement of ammonia emissions from livestock farms
Tools to encourage farmers, land managers and decision-makers to reduce ammonia emissions
We are developing tools to encourage farmers, land managers and decision-makers to reduce ammonia emissions. This includes a farm-level scenario-based ammonia footprinting and decision support model to drive the uptake of ammonia mitigation strategies in ruminant production systems. We are demonstrating a tool to predict ammonia losses from organic and inorganic fertilisers and impacts on air quality and nitrogen deposition. This activity includes:
- A literature review
- Creating an inventory of technologies and strategies for the reduction of ammonia emissions
- Developing a user-friendly, farm-level spreadsheet-based footprinting and decision support tool for ammonia emissions from ruminant production systems
- Preliminary footprinting of farms, recommending low-cost interventions to reduce emissions, regular re-foot printing with additional recommendations to demonstrate the benefits
Exploring trade-offs
Both intensive and extensive ruminant production systems are common in Scotland: however, there are inherent trade-offs between low ammonia emissions (extensive systems) and low methane emissions (intensive systems). There is a need for underpinning science to understand and quantify these trade-offs, to better inform policy development and identify optimum combinations of ammonia and GHG emission mitigation measures. We are investigating trade-offs between reducing methane emissions through intensive production systems and reducing ammonia emissions through extensive production systems.
Ammonia emissions from ruminant livestock farming: filling knowledge gaps
This project is identifying knowledge gaps around strategies to reduce ammonia emissions from ruminant production systems and how interventions to reduce ammonia may have unintended consequences for GHG emissions. We are designing a programme of practical and desk-based studies to address these gaps.
New approaches for air quality monitoring and response
Horizon scanning and work package refinement
We are scoping out new approaches for air quality monitoring and response, and assessing the potential limitations and barriers of Apps and other web-based services that could be used by the farming community.
Developing an emission scenario impact assessment tool
We are developing a web-based scenario impact tool that allows Scottish farmers and policymakers to run farm-based abatement scenarios, such as a change in manure management or animal housing, and at the same time assess their impact on the exceedance of impact limits on nearby protected habitats. The model is based on an improved and higher-resolution meteorological dataset for Scotland.
Demonstrating real-time ammonia source strength analysis using real time data
With low-cost systems for real-time monitoring of farm ammonia concentrations on the horizon, we are demonstrating how such data may be used to estimate, in real time, the source strength causing the concentrations.
Thus, we are contributing to an improved understanding of mitigation strategies targeting both ammonia and GHG emissions and aligned farm-level decision support mechanisms that can be directly implemented on Scottish farms.
Project Partners
Progress
Create an inventory of existing and emerging technologies for the reduction of NH3 emissions (Objective 1)
In Year 1 efforts were concentrated on building up a bank of literature on ammonia (NH3) mitigation measures and their effectiveness. This included a literature review and development of an inventory of NH3 mitigation measures. This inventory is being incorporated into a wider inventory of mitigation measures for all agricultural emissions. A common structure has been agreed upon for this inventory and we will continue to incorporate the inventories in Year 2.
Development a farm-based tool to support the uptake of those NH3 emission technologies by Scotland's farming sector (Objective 2)
Using inputs to Agrecalc as a basis, a spreadsheet tool has been implemented for NH3 emissions from livestock (from nitrogen excretion and manure management at housing and storage) and from land use (fertiliser and manure application). Ammonia mitigation and abatement measures based on the UK National Ammonia Inventory (2021) have been added, with magnitude of mitigation/abatement cross-referenced against peer reviewed published literature. In Year 2 we will complete this tool and begin recruiting case study farms to demonstrate its use and impact.
Development of a farm-based tool for assessing the impact of on-farm mangement options on nearby habitats (Objective 3)
Work on this objective will begin in Year 2.
Investigate trade-offs between ruminant production systems which reduce NH3 emissions and those which reduce methane emissions (Objective 4)
There are few studies that measure both NH3 and methane emissions. We are identifying studies which measure proxies for methane (dietary information) and NH3 (nitrogen digestibility) and will use these in a meta-analysis. This will be published in a scientific paper in Year 2. We will also use the foot printing tool developed in Objective 1 and farm scale carbon foot printing tools (such as Agrecalc) to model trade-offs in emissions under specific conditions.
Identify gaps in knowledge around NH3 emissions and trade-offs between NH3 and methane emissions (Objective 5)
Knowledge gaps will be identified from the literature review generated in Objectives 1 and 4 and we will design experimental work to address these in Year 3.
Demonstrate the utility of emerging NH3 monitoring technologies for real-time on-farm emission estimation (Objective 6)
Work on this Objective will begin in Year 3.
Horizon-scan opportunities to exploit existing and emerging data sources, measurement technologies and data tools (Objective 7)
During this Objective data sources (including Earth Observations), measurment technologies (e.g., sensors) and data tools will be investigated to identify, monitor and predict air pollution hotspots and to develop timely mitigation responses, with a particular focus on pollution from the land-based sector and on ecosystem impacts. It is also envisioned that this approach will implement exemplars. Work on this Objective will begin in Year 2 with a scoping study to identify new and emerging technologies for measuring NH3 and identifying NH3 emission hotspots.
Year 2 Progress for the four Work Packages (WP):
WP1: Develop a farm-based tool to support the uptake of ammonia emission technologies by Scotland's farming sector. Using inputs to Agrecalc as a basis, a spreadsheet tool has been developed for ammonia emissions from livestock (nitrogen excretion and manure management at housing and storage) and from land use (fertiliser and manure application). Ammonia mitigation and abatement measures based on the UK National Ammonia Inventory (2021) have been added, with magnitude of mitigation/abatement cross-referenced against peer reviewed published literature. The tool is complete and we will demonstrate its use and impact initially on SRUC research farms (dairy and beef) in Year 3 and showcase the tool at an on-farm KE event, recruiting commercial farms once the tool has been practically demonstrated.
WP2: Evaluation of trade-offs between ammonia and GHG emissions, using the model developed in WP1. A meta-analysis investigating the trade-offs between ammonia and methane emissions from individual dairy cows after nutritional interventions to reduce one of these gases was completed. The analysis showed a wide range of responses in terms of changes in these two gases relative to each other in response to treatments, but the mean responses resulted in reductions of both gases (e.g. a win-win situation). An abstract has been submitted to international conference to present these findings. A further meta-analysis investigating trade-offs between ammonia and GHG emissions from slurry stores with different cover types is being undertaken as part of an Undergraduate student Honours project and will be complete by the end of Year 2. Scenario based modelling (using the tool developed in WP1 and Agrecalc) investigating trade-offs between ammonia emissions and GHG emissions is underway.
WP3: The outcomes from WP1 and WP2 in Years 1&2 will be used in Year 3 to develop a programme of research to fill knowledge gaps in Years 4 and 5. We have purchased equipment for spot monitoring of ammonia emissions. A methodology for using this equipment in Years 4 and 5 will be developed throughout Year 3.
WP4: Scoping study of emerging measurement technologies, sensors, apps, earth observation products and datasets. A report on the current state-of-the-art in ammonia measurement technologies will be delivered by the end of March 2024. This summarises state-of-the-art real-time measurement approaches, available (low-cost) sensors, mainly based on electrochemical sensors, and the state of play of available and forthcoming satellite products. This report will provide the basis to refine WP4 going forward. Preparation has started to develop an improved dispersion and screening tool for ammonia emission impact assessment.
The results of this project will be presented to members of the Scottish Government Rural and Environment Science and Analytical Services Division in March 2024. Understanding trade-offs between different gaseous emissions will aid in the cohesion between different policy objectives and will help improve farmer and consumer confidence leading to greater uptake. We have hosted several visits by industry to our research farms (farmers, processors, feed companies, technology companies, agricultural press, funding bodies and industry bodies such as AHDB, QMS, NFUS) where we have discussed this project alongside our wider programme of research on ruminant production. We (SRUC and CEH) have recently formed a new collaboration with a commercial company to develop a laser-based technology for use in agricultural settings (grant application submitted). This technology will be able to measure ammonia and GHGs simultaneously, in real time and across long distances (e.g. across a field). We have also hosted visits from many student groups throughout the year, including SRUC students, students from other UK Universities and colleges (University of Edinburgh and Harper Adams), and study tours from the USA (Oregon State University, University of Arkansas, Trent University Ontario). During these visits we have discussed mitigation measures and potential trade-offs between different gaseous emissions.
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