Air quality: livestock farming and ammonia

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

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.