In 2018, agriculture accounted for 18% of Scotland’s total greenhouse gas emissions (GHG), with a significant share coming from nitrogen fertilisers. One policy approach identified as having potential to reduce nitrogen fertiliser use is through leguminous crops to fix atmospheric nitrogen. 

This study assesses the opportunities, challenges and barriers influencing potential production of grain and forage legumes in Scotland. Grain legumes are crops such as beans and peas while forage legumes include lucerne (also known as alfalfa), clover and vetch.

We assess the climate mitigation potential of legumes within arable and grassland rotations and comment on the potential to reduce reliance on imported protein.

Key findings

Current production and trends

• There has been a historical decline in the grain legume area in the EU, largely as a result of economic forces. This is matched in Scotland – there is a low level of production (2.3% of the tillage crop area in Scotland).
• Use of legumes within forage grazing is an accepted practice in Scotland and large areas of improved grassland benefit from their inclusion. There is little scope for an expansion in the area of legumes in pasture.

Availability of land

• There is a large area of land which is theoretically suitable for legume crops growth. Generally, the most suitable land lies in the east of Scotland and the lowlands. However, Scotland’s climate can pose issues for cultivation, leading to a perception among some farmers of poor crop performance.
• Climate change is not expected to have a major effect on the area of land that can support legume crops in Scotland. 

GHG emissions

• The main way to reduce GHG emissions is through crop substitution, increasing the use of leguminous crops. This results in changes in nitrous oxide emission from soil (through changes in nitrogen fertiliser use and crop residue returns to the soil); and lower emissions from manufacture of nitrogen fertiliser (occurring outwith Scotland).
• Including legumes in crop rotation, one year in five, could lead to an annualised nitrogen saving of 30.8 kg/ha. This is a saving of 24.1%.
• The savings in GHG emissions from including legumes are 107.4 kt CO₂e/yr, rising to 160.8 kt CO₂e/yr when fertiliser manufacture GHG emissions (outwith Scotland) are included. This is equivalent to 1.4% of Scotland’s agriculture emissions, rising to 2.2% when fertiliser manufacture GHG emissions are included.

Market and other constraints and opportunities

• The UK is reliant on imports to provide 47% of protein sources used in animal feeds. With greater awareness of the need for sustainable protein, the importance of domestic protein sources is set to increase.
• Economic conditions for both demand and supply are key influences on the area of legumes grown. As an ingredient in animal feed, legumes can be uncompetitive with other protein sources. 
• From a grower’s perspective, the price paid for legumes is too low and other cropping options give higher and more reliable returns. However, new markets for human food ingredients and a growing demand in the fish feed sector could offer opportunities.
• There are a range of technical and logistical limitations which depress the market for grain legumes. These may require some intervention but should not be significant, long-term barriers.
• Perceived poor performance of grain legumes in Scotland has suppressed the area cropped. However, greater awareness amongst the industry of the potential of legumes to support more sustainable rotations and soil health, and to help manage disease and “regenerate” land, are increasing interest.

Scotland is committed to meeting a net-zero target for greenhouse gas (GHG) emissions by 2045. Agriculture and the land use sector can help in two ways: by changing practices to reduce GHG emissions and by storing carbon in the soil and plants. In 2018 agriculture and related land use was responsible for 23% of total Scottish emissions. 

The Climate Change Plan (CCP) is a key policy tool which was revised in December 2020 (after this research was completed) to help Scotland meet the new net-zero target. Policy development is informed by the Scottish ‘TIMES model’. This model pulls together emission, mitigation and mitigation cost data from all sectors to help understand the strategic choices required to decarbonise an economy. It identifies the effectiveness of carbon reduction measures to enable a consistent comparison of the costs of action across all sectors.

To ensure the model uses the most recent data for agriculture, our research updated estimates of the mitigation potential and the cost-effectiveness of a selection of agricultural mitigation options. It took into account the significant recent improvements in UK agricultural GHG inventory reporting (Smart Inventory).

We assessed 14 farm technologies and practices which can reduce GHG emissions in Scotland. Some of these measures can be applied to multiple types of livestock, raising the number of mitigation options to 21.

The aim was to estimate the different measures’ average mitigation potential, capital and recurring costs per unit (e.g. hectare or animal), and total maximum applicability on-farm. 

Key findings

• The mitigation measures applicable to agricultural land can save between 7 and 553* kg CO₂e every year on each hectare where they are applied. The single most effective measure is increased cultivation of grain legumes (i.e. peas and beans) which provides 553 kg CO₂e per hectare savings annually (see Table 1). The second and third most effective measures (on an area basis) are variable rate nitrogen and lime application (precision farming) and soil pH management (i.e. liming when necessary), providing 151 and 112 kg CO₂e mitigation per hectare annually, respectively.
• Intercropping can provide the highest cost savings to farmers per hectare per year (£45); variable rate nitrogen and lime application, crop varieties with higher nitrogen use efficiency and soil pH management can also provide savings. Grain legume cultivation is the most expensive option (£406 per hectare per year).
• The cattle mitigation measures assessed can save between 57 and 854 kg CO₂e every year for each animal they are applied to; 3NOP feed additive, breeding for low methane emissions and slurry store cover with impermeable cover are the most effective.
• Cattle measures’ net costs range from a saving of £359 to a cost of £31 per animal per year. The dairy breeding measure could save £359 per animal per year, and improved health of dairy animals, dairy precision feeding, beef breeding for low methane emissions and covering beef slurry stores can also save farmers money. The most expensive cattle measure is administering 3NOP feed additive to beef animals (£31 per animal per year).
• The sheep measure investigated can provide 15 kg CO₂e mitigation per animal annually and a cost saving of £0.36 per head.
• The two measures applicable to pigs could reduce emissions by 25 and 86 kg CO₂e per head per year, for a £0.87 saving or cost of £0.52 per animal per year, respectively.

It is important to note that these are average estimates. On an individual farm basis, both the mitigation and the net costs can be very different. 

* Three changes have been made to the original report download:

– The Executive Summary stated that the mitigation measures applicable to agricultural land can save between 7 and 151 kg CO₂e every year on each hectare where they are applied. The second figure should have been 553kg. This has now been corrected above and in the pdf.

– The original omitted three of the authors.

– In Section 3.2.2, a reference to Defra’s support has been added.

If Scotland is to achieve its ambitious net-zero greenhouse gas emissions target by 2045, bioenergy crops present one option as an integral part of the energy supply system.

The Committee on Climate Change (CCC) has identified that under net-zero emissions scenarios, bioenergy supplied in the UK could reach 200TWh (with 170TWh of this sourced from the UK) by 2050. The CCC considered that UK-produced energy crops could be an important source of bioenergy and assumed that around 700,000 ha could be planted in the UK to help achieve this target, although it did not consider where. If it were evenly spread across the arable area of the UK, Scotland’s ‘share’ would be about 70,000 ha.

This report examines the potential for a sustainable expansion of perennial bioenergy crop production on low-grade agricultural land or underutilised land, focusing on short rotation coppice (SRC), miscanthus and short rotation forestry (SRF). The aim was to understand the potential implications of any expansion, as a basis for further discussion.

Key findings

The theoretically suitable total land area identified across all three crops and land types, which include grassland, is more than 900,000 ha; suggesting that Scotland could make a substantial contribution to the area of UK energy crops, and meet its ‘share.’ The theoretically suitable total land area is shown to decline when grassland areas are excluded.

In terms of total area, geospatial modelling shows a theoretical potential for each crop type in Scotland (based on current data) of :

• 912,600 ha of suitable land is currently available for planting of SRF,
• 219,100 ha is available for SRC and
• 51,800 ha is available for miscanthus.

The areas can overlap and are therefore not mutually exclusive.

The majority of this theoretically available land is located in the east of Scotland and the lowlands. The availability of this land will be limited by a range of other factors, for example the need for land for other uses, such as fodder production, forestry (non-energy) etc.

The theoretically available land could provide the following energy yields:

• 50TWh/yr and 5.78Modt/yr for SRF,
• 25TWh/yr and 1.75Modt/yr for SRC and
• 59TWh/yr and 0.52Modt/yr for miscanthus.

Overall constraints are more severe for miscanthus than for SRC or SRF. The following constraints have high impacts on potential production area:

• Winter hardiness of miscanthus is a major constraint for this crop in much of Scotland.
• Current varieties of miscanthus are constrained by climate to the south and south east of Scotland (Towers, 2013).
• Soil carbon loss is a constraint for SRC expansion. There is a large area of land in Scotland with high levels of soil organic carbon and this land is susceptible to loss of soil carbon when it is cultivated. For SRF this constraint is less relevant because there is less soil cultivation but planting of trees on blanket bog (peatland) should be avoided (as recommended in the UK Forestry Standard (Forestry Commission, 2017)) because of habitat loss and carbon loss as a consequence of drainage.

Using a UK Climate Projections 2009 (UKCP09) medium emissions scenario for a changing climate, we found that the expansion in suitable land is between:

• 22-25% of the current theoretically suitable land area out to 2030 and between 29-30% of the current suitable land area out to 2045 for SRC and miscanthus.
• However, the suitable land available for SRF is shown to decline by 3% by 2040.

Overall, the data do show that there are opportunities for energy crop expansion both currently and under a changing climate.

The Scottish Government established the Climate Challenge Fund (CCF) in 2008 to help local communities in the transition to a low-carbon society. The fund supports community-led projects which lead to reductions in carbon emissions, and which are designed to leave a sustainable legacy of low-carbon behaviour.

It works in areas such as energy efficiency, sustainable and active travel, reducing and recycling waste, and food growing. As of mid-2020, over 1,150 projects across all Scotland’s 32 local authorities had been awarded CCF grants, with total funding since 2008 exceeding £111 million.

This report considers the evidence for the fund’s impact on the ground, the effectiveness of actions, and how we can monitor success in the future. Emerging findings were captured during the research in a series of interim policy notes, also published here.

The research centres on in-depth case studies of five CCF projects which the team followed for 18 months. The report uses the case study evidence to understand and capture the processes of change supported by the CCF. From this, it draws out lessons on how to facilitate and monitor such impact going forward.

Welcoming the report at the CCF Annual Gathering 2020, Cabinet Secretary for Environment, Climate Change and Land Reform, Roseanna Cunningham MSP, said:

I thank the research team for all their efforts on the study which, as they presented in one of the break-out sessions at last year’s Gathering, centred on in-depth case studies of five CCF projects.

Its findings and recommendations will help to identify the specific role that community climate action can play in Scotland’s transition to a net zero society and, crucially, in ensuring that we take everyone with us on that journey.

Findings

• The CCF’s community focus allows it to play a unique role in Scotland’s transition to a low-carbon society. This research identifies that CCF projects contribute to Scotland’s transition to a low-carbon society at the community level in two ways:
  • by directly helping people to explore and adopt low-carbon behaviours; and
  • by building community capacity to embed a legacy of continued bottom-up change that can also support larger-scale policy interventions.
• The CCF’s unique contributions are not adequately captured through the lens of carbon emissions. This echoes findings from earlier reviews of the CCF.
• Current carbon-focused CCF monitoring and reporting processes present several limitations.
• The CCF programme faces similar issues to other community empowerment policies. As such, its design could usefully reflect the barriers and opportunities faced by community projects in general.

Recommendations

Moving Beyond Carbon Emissions

1. The CCF programme should seek to address all the elements of Climate Change Engagement.

Better Capturing and Reporting CCF Success

2. We suggest reporting along the lines of the proposed Climate Change Engagement framework.
3. Reporting processes need to be realistic.
4. It is important to separate supporting and assessment functions in the reporting process.

Making the Most of the CCF’s Community Focus

5. CCF projects could be given more guidance and support to identify and respond to their communities’ specific characteristics.
6. The CCF funding approach should reflect diverse community capacities.
7. The CCF could empower projects to be adaptive over the course of the funding period.

Soils are a critical resource, not only for food production and biodiversity, but also for managing water and storing carbon. Efficient management of agricultural soil is thus a key element of long-term sustainability.

CXC commissioned the James Hutton Institute to develop a free, easy-to-use tool for land managers to enable them to compare the measured organic matter and carbon content of their topsoil to typical values for Scotland.

The tool is based on the National Soils Map of Scotland data (as currently available on Scotland’s Soils website) and provides reference/context information for the measured organic matter value at any site.

The soils data is processed within the platform so that the input required by the land manager is as simple as possible and optimal data is used.

The tool aims to help land managers understand quickly whether the soil in a particular area has good organic matter content, and alert them to the need for further action.

The tool can be accessed on the James Hutton website at: https://om.hutton.ac.uk/

Lead researchers: David Donnelly and Allan Lilly

This report was commissioned to analyse the indicators available to monitor Scotland’s soil health. Soil health is essential: the benefits range from food production to filtering water, reducing flood risk and regulating climate.

The second Scottish Climate Change Adaptation Programme (SCCAP) identifies soil health as a priority research area, following concerns over a perceived lack of data or gaps in understanding Scotland’s soils. This study summarises previous work on Scottish soils, explores existing datasets, and identifies metrics to support the monitoring of soil health and the vulnerability of Scottish soils to climate change.

 Key findings

• Scotland has a significant, world-leading soil knowledge base and a broad data resource portfolio. However, the existing evidence base does not contain tools identified as appropriate for monitoring change in Scottish soils.
• Thirteen indicators with potential to measure soil vulnerability to climate change in all soil types were identified.
• A total of 41 existing datasets that contain baseline and/or resurvey data for Scottish soils have been identified. Resampling of some of these long-term national datasets has potential to support further development of the 13 identified indicators (Table A10).
• A critical knowledge gap exists regarding the dependencies of the 13 identified indicators (i.e. factors they are reliant on), their interactions and hence whether a reduced core set of indicators could be identified at a future stage. This is compounded with critical gaps in our understanding of the interactions between soil properties. This knowledge gap has a major impact on soil biological diversity and therefore functioning of the soil system.
• No single indicator measures the full range of relevant properties encompassing all soils or climatic conditions.

Increasing woodland planting is a land use change that will help Scotland achieve its statutory commitment to achieve net-zero greenhouse gas emissions by 2045. Scotland’s Climate Change Plan includes commitments to incrementally increase the annual woodland creation target from 10,000 to 15,000 hectares per year by 2024/25.

This short study updates a Woodland Expansion Advisory Group (WEAG) 2012 report that provided detailed analysis of the land area that might be suitable for new woodlands. It summarises the results of an initial re-analysis of the opportunities and constraints for woodland expansion, using a GIS spatial analysis. It finds that the estimated land area suitable in principle for woodland creation has risen by 270,000 hectares, 10%, to 2.96 million hectares.  This is due to changes in peat soil classification and extent (-263,352 ha) and the inclusion of potential planting on higher quality agricultural land (+533,352 ha).

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. 

Main findings  

• 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.

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Scotland’s Climate Change Plan makes a policy commitment to reduce greenhouse gas (GHG) emissions from nitrogen fertiliser through improved understanding, efficient application and better soil condition.

This report considers the potential for nitrogen and urease inhibitors to support emission reductions in Scotland, considering Scottish circumstances and conditions, such as soils, crops, rainfall and temperature.

These inhibitors are particularly important for those who are modelling both GHG emissions and air quality. However, while some studies provide consistent messages concerning the evidence of their effectiveness and their impacts on the wider environment, others are contradictory.

Main findings

The evidence indicates that:

• There is generally a positive potential impact of inhibitors on GHG and ammonia emissions under Scottish conditions, especially for nitrification inhibitors.
• There are no significant concerns over the efficacy of inhibitors in Scotland. Low uptake relates to the niche market; inhibitors are primarily supplied for agronomic benefit with relatively marginal economic gains in most circumstances.
• While the efficacy of inhibitors has been confirmed by the review, there remain uncertainties over the magnitude of emissions reductions. There are also questions relating to the environmental risk, trade-offs with potential emission/pollution switching, industry knowledge and practical implementation.
• The persistence of the effects for both nitrification and urease inhibitors are likely to be impacted by a warmer climate, although any impact is likely to be minimal. Emissions from unabated fertilisers are expected to increase as climate change progresses. Under these conditions, the role of inhibitors as a tool in mitigating emissions becomes increasingly important.

The evidence for environmental risks includes:

• There is little evidence exploring the impacts of N inhibitors on soil health and on impacts to non-target and nitrifying organisms.
• Use of nitrification inhibitors can lead to increases in ammonia emissions. However, alongside this, there are benefits for other environmental indicators (particularly GHG emissions and nitrate leaching). The potential increase in ammonia emissions can be mitigated by use of nitrification and urease inhibitors together.
• Some research highlights the risk of DCD (dicyandiamide – a nitrification inhibitor) leaching into surface and ground waters. This can have adverse effects on aquatic systems.
• There are concerns regarding animal consumption (directly or via traces found on grass/hay) as DCD has been found in dairy products in New Zealand. This led to DCD being banned in New Zealand.
• Increased risk of ammonia release from use of nitrification inhibitors will have adverse impacts on ecosystem biodiversity through deposition and increased N loading to sensitive sites.

The main practical/commercial considerations are:

• Nitrification and urease inhibitors are not widely used due to poor cost effectiveness under conventional economic analysis at farm gate (i.e. not considering externalities of environmental or societal costs).
• In the agriculture industry, there remains significant misunderstanding over the roles and practical application of inhibited fertilisers.
• Investment in nitrification inhibitors will not be driven by market pull. Stakeholders feel N inhibitors are not currently attractive prospects for increased investment.
• Urease inhibitors are more commercially viable (compared with nitrification inhibitors) and have potential economic benefits due to the potentially high emissions of ammonia losing significant N content. Interest and awareness of urease inhibitors is greater.
• Price sensitivity: farmers in the UK are very sensitive to fertiliser price and will seek the most cost-effective source of N. A perception of little or no economic value in inhibited fertilisers will discourage adoption.

Key findings include:

• Species choice is a social as well as an economic and technical choice, because different people involved in land use have different objectives and preferences.
• Tree nursery producers, forest managers and sawmill businesses all influence species choice through supply and demand relations, as well as through preferences and shared values
• Stakeholders experience risk in different ways.
  • Nursery businesses are bearing the most tangible component of risk at the outset, and paying the cost of low confidence in policy direction.
  • Sawmills are adapting to a wide range of species, and more than they are usually credited with.
  • The private investment forestry sector is the least interested in change, because most of their clients are driven by the search for high returns on their investments. 
  • Public forest managers are committed to diversification but are forced to take an experimental approach because of the scarcity of experience and site-specific information on cultivating alternative species.
• Both private and public forest managers identify deer populations, and their preference for browsing species other than spruce, as a particular constraint to commercial diversification.