Scotland’s Climate Change Plan includes a policy commitment to reduce emissions from the use and storage of manure and slurry.
Agriculture and associated land use account for 24% of greenhouse gas (GHG) emissions in Scotland, with methane the most significant proportion of this at 44%. Methane comes from manure and enteric fermentation. The management of manures is therefore a critical element in mitigating the sector’s GHG emissions.
This study examines the feasibility of developing manure exchanges (slurries and farmyard manures) to reduce these emissions.
- The arisings of manure in Scotland indicate a total available nitrogen supply of 14,700 tonnes per annum from manure, compared with a total utilisation of applied nitrogen of approximately 152,000 tonnes.
- A significant proportion of manures could potentially be part of a manure exchange, with just 6% of manure arisings currently reported as being exported from source.
- The potential abatement of GHG emissions by offsetting manufactured nitrogen through the substitution of organic manure is limited. Under the most favourable scenario modelled, the potential saving is equivalent to just 0.68% of annual agricultural emissions.
- We found three broad examples of schemes which support the movement of manures and would be relevant within the Scottish context: muck-for-straw, manure exports and movement of livestock.
- Requirements for nitrogen are greater in all major regions of Scotland than can be supplied by manure sources.
- Compared with other European countries, Scotland does not have a significant oversupply of livestock manures at a regional level.
- There are environmental challenges associated with manure and slurry production and storage at an enterprise level, particularly for water quality. The potential for local surpluses has therefore been the focus of this study.
- Surpluses of manure can lead to localised environmental impacts if they are not managed correctly. The factors influencing the success of manure exchanges rely on the recognition of costs and barriers and on investment in establishing agreements.
- A strategic, regional or national scale exchange model is unlikely to be cost effective for GHG gas abatement. However, there is some potential to support exchanges of manure through improved local distribution (i.e. within a holding or with close neighbours).
- The most useful measures are those that focus on the utilisation of manure nutrient value and that form part of an integrated policy alongside other drivers such as water quality (Water Framework Directive), Nitrate Vulnerable Zones, air quality and productivity.