Soils are one of the world’s biggest stores of carbon. The level of carbon storage depends on several factors, including the type of organic matter, climatic conditions and land management practices, both past and present. This report explores how the level of storage over time could be measured, and how this could help improve land management practices through a payment system.

Key points

• Agricultural soils (across pasture and arable) account for more than 10% of Scotland’s estimated soil carbon. Changes in land management practices affect the balance between soil carbon accumulation and loss, with conversion from grassland to cropland as the largest single change that releases soil carbon on Scottish agricultural land. 
• Evidence suggests there is large potential for increasing carbon storage in agricultural soils through changes in management practices. Any increase in carbon in the soil is likely to have a positive impact on soil quality, whilst the climate change mitigation benefit may be modest but positive in the longer term.     
• Mechanisms for support through payments exist, but they are largely focused on wider benefits such as preventing soil erosion and there are none that currently specifically enable  soil carbon sequestration.

Key points

• We found that undisturbed bogs, and restoration sites older than 15 years do help to combat climate change by storing more greenhouse gases than they emit.
• Despite some uncertainty, our results showed a clear contribution to global climate cooling in the decades following peatland restoration. While disturbance tended to increase greenhouse gas emissions, this is compensated by the amount of net climate cooling after 15-20 years.
• We need to continue monitoring to understand the effect on the climate over longer time scales.
• The results confirm the benefits of forest removal on deep peats where conifer yields have been low. In addition to habitat improvements, we found a long-term climate benefit that is unlikely to be matched by forestry. Newer management techniques, such as intensive drain and plough-furrow damming may help faster recovery of carbon sequestration
• Continued monitoring of vegetation response and water table depth across a network of sites is advisable to inform cost-effectiveness of restoration after forest removal.

While the science is complex and there are still things we don’t know, we found that restoring peatlands previously planted with conifer forests has clear benefits over the medium term.

In the 2018 Climate Change Plan, the Scottish Government committed to a reduction in emissions from the use of synthetic nitrogen fertiliser, which currently accounts for around 25% of the GHG emissions from agricultural soils. One approach is to increase cultivation of nitrogen-fixing crops also known as legumes, which convert nitrogen from the air into a form that is biologically useful.

The evidence base for the effectiveness of nitrogen fixing crops is largely based on research and experience at a UK and European level. ClimateXChange was asked by Scottish Government to explore the current state of confident knowledge for their application, and their potential benefits for farm business (commercial as well as on-farm) under Scottish circumstances (i.e. soil, climate, markets, etc). 

80% of current demand for legume products in Scotland is imported, mainly for animal feed, but also for human consumption.

There is a long history of growing legumes in Scotland and a considerable potential to increase legume production. However, there is limited opportunity to access commercial seed stock as current markets are focused on more-temperate climates, and there is also a lack of processing facilities in Scotland.

An increase in legumes grown in place of another crop as part of a rotation and with no added fertiliser, could give significant savings in terms of fertiliser-offset depending on the crop.

Farm-based carbon audits are one of the tools that might help reduce greenhouse gas emissions in the farming sector. This report compares the available tools to assess their potential application in Scotland.

Key findings:

• 64 potentially applicable tools were identified through a web search. Of these, nine were selected for more detailed comparison. Analysis found that a further six were not suitable due to a variety of shortcomings (e.g. general purpose of the tool, major limitations in comprehensiveness, lack of transparency).
• Only three of those tools would be suitable for farm level carbon audits in Scotland:
  1. AgRE Calc
  2. Cool Farm Tool and
  3. Solagro (JRC) Carbon Calculator
• These tools follow a similar calculation framework (international guidelines and international calculating standards), although none can be judged to be fully comprehensive. Although currently free to use, maintenance and development of the carbon audit framework requires continuing investment. In addition, their application needs to be embedded in wider environmental and farm context in the form of advisory support (i.e. the tool should not be the sole information source for decision).
• The comprehensiveness and practicality of each tool varies between production systems (e.g. crop production, livestock production, carbon sequestration). No tool is fully comprehensive, and each can only handle a limited amount of possible emissions reductions on farms. None of the three recommended tools considers embedded emissions in livestock bought in.

The Peatland Research and Monitoring Group are exploring how identify priorities for monitoring peatland condition in Scotland. ClimateXChange organised a workshop of experts to explore the concept of peatland condition (the ‘what’) and identify what datasets (the ‘how’) are needed.
 
We recognised that developing a monitoring strategy is a huge task and could not be achieved with one meeting. The aim of this event was to bring the professional perspectives of delegates together to agree a basis for action, highlighting the key priorities and identifying realistic and definable tasks that could be taken forward.

Sustainable soil management is a particular challenge as Scotland adapts to a changing climate, and has been highlighted by the Adaptation Sub-Committee, in its UK Climate Change Risk Assessment 2017. Soil compaction and erosion have been identified as being important, particularly in exacerbating flooding impacts and decreasing soil carbon storage.

This report collates the current state of confident knowledge for Scotland – what we know, what we don’t know and what is under active debate.

Key findings

• Much of what we know about erosion rates on agricultural land in Scotland comes from a few, individual studies of erosion events, but there is a growing body of evidence that can be used to examine the role of land use (both current and historic), soil type and slope on erosion susceptibility. Other factors such as antecedent moisture content, ground cover and presence of tramlines also play a role, making it difficult to be certain when, or if, erosion will occur.
• Soil erosion models with sediment yield as an output seem to exaggerate the amount of soil loss and are difficult to validate, although they do offer a way to examine the relative changes in erosion rate under different land uses and changing climates.
• There is a link between soil compaction and erosion; soils that become compacted have a restricted capacity to store rainfall and generate overland flow more quickly than soils that are not compacted. This overland flow can then cause erosion.
• The greatest driver of soil compaction is machinery weight, which has been increasing over the past few decades, although using wide tyres, dual wheels and low pressure tyres can reduce the impact.
• We have a better understanding of field level effects with evidence gathered in Aberdeenshire following storm Frank (December 2015) suggesting erosion seemed more prevalent in areas that were more intensively managed.

Agro-forestry is the integrated use of trees on a farm or small holding for a wide range of benefits.  The Scottish Government has set statutory targets for the reduction of GHG emissions in Scotland through the Climate Change (Scotland) Act 2009. Agroforestry in Scotland is one option that could help achieve these targets, while also supporting sustainable adaptation to a changing climate.

This report identifies the wide range of potential benefits of increasing the use of agroforestry practice in Scotland and will support further discussion towards implementation.

The boundary between productive land and hill land in Scotland has moved over time, in response to climate and also to market demand. Scotland’s climate is changing, and this will mean changes for those areas of Scotland that sit on the margins of productive agriculture.

In this context sustainable soil management is a specific challenge as Scotland adapts to a changing climate.

This report examines the four dominant ways that farmers will adapt to climate change, and their impact on different services.

Key findings:

• It is likely that land use change will result in the intensification of land management. The result would be a reduction in most aspects of natural capital including soil carbon, water quality and biodiversity. An increase in arable cropping from current levels and a switch to winter cereals could increase soil erosion and flood risk.
• An exception would be the potential increase in forestry and woodland, though the benefits of planting depend greatly on what is planted and where it sits within the landscape or catchment.
• It is particularly difficult to assess the likely changes in livestock numbers. This makes it difficult to assess the greenhouse gas emissions from their rearing, as it is not possible to predict the balance of their removal to allow arable cropping, the increase in extensive livestock management which would affect emissions intensity, and the intensification of management on currently more marginal ground.
• One approach to assessing the risk of autonomous adaptation would be to model the impacts of a set of scenarios of change so that comparison could be made with changes expected from other drivers; if potential impacts are large in comparison then greater attention would need to be given to strategies to avoid or mitigate impacts.

This project looked at improving the measurement of the GHG emissions intensity of the main agricultural commodities at a national level. 

The Scottish Agricultural Emissions Model (SAEM) calculates the amount of commodity produced per herd/flock or per hectare of crop and the GHG emissions arising from this production. The emissions intensity of the commodity can then be calculated.

SAEM complements the UK GHG Inventory by providing estimates of the emissions intensities of the main agricultural commodities in Scotland. SAEM uses the IPCC’s widely accepted and transparent Tier 2 approach to calculating GHG emissions, which has a clear scientific rationale as is consistent with the UK GHG Inventory approach.

Using SAEM does require a moderate knowledge of MS Excel and some familiarity with agricultural processes and the emissions arising from them. SAEM is therefore not intended for use by the layperson or occasional user but provides experienced users with significant scope for investigating the drivers of agricultural emissions.

We derive a wide range of benefits from how we use the land; it underpins our economic prosperity, supports the provision of essential supplies of food and clean water. Its sustainable management is essential to how we reduce our greenhouse gas emissions, and adapt to a changing climate. 

‘Payment for Ecosystem Services’ schemes have been developed in a broad range of areas that seek to support good environmental management. Common to all the schemes is that they take a voluntary approach to offering financial incentives to land-managers for actions that maintain or enhance services that are not routinely bought and sold or provided through regulation.

The characteristics of different ‘Payment for Ecosystem Services’ schemes vary considerably. For the purposes of meeting climate change needs, ‘Payment for Ecosystem Services’ has substantial potential but with several key issues:

• The degree to which participation by actors, particularly providers can be facilitated.
• The type of scheme (inputs or outcomes based), the structural arrangement for the relationships between actors and how well it fits with the objectives.
• How well the scheme balances the need for supply of other ecosystem services (and biodiversity).