Developing a method to estimate the costs of soil erosion in high-risk Scottish catchments: final report

9. Implications for policy and practice

Policy interventions are needed if soil resources (and the services they provide) are being degraded, compromising progress towards sustainability goals. Policy intervention may also be considered where soil resources are at risk of being degraded. Quantifying the degree and extent of soil erosion can be used to identify priority areas in need of soil protection. Quantifying the costs of soil degradation (here specifically, soil erosion) can be used to justify the need for and expenditure on soil protection interventions that control or even reverse the damage being done to soils. This logic can be applied at the local, regional and national scale.

Table 76 in Appendix 10 provides details of the key policy instruments in Scotland and their applicability to soil erosion. Key highlights from the analysis of current policy / legislation dealing with specifically soil erosion in Scotland are summarised below.

• There is no policy related specifically to soil protection in Scotland (McKee, 2018). Most policy instruments are not explicitly designed to target soil, rather they view soil as an asset that underpins agricultural production, water quality or climate change mitigation (Prager et al., in press).
• It is difficult to define and bound Scottish environmental policies (Prager et al., in press), specifically those that relate to soil. It is not always clear how to map the parent policy to an Act and a delivery mechanism. This has implications for the uptake of mitigation measures for soil erosion.
• In many cases the policy instruments related to soil erosion are framing principles and standards, rather than policies addressing environmental protection and regulation.
• Key regulatory policies relate to only very specific situations, with small areas or areas under low risk scenarios or those that have not been modelled in this study. For example there are requirements to minimise soil erosion during land development (Environmental Assessment (Scotland) Act) or to minimise disturbance in protected areas (The Conservation of Habitats and Species Regulations).
• Areas that are likely to have high soil erosion risk (due to vulnerable soil type and land use combinations - e.g. intensive arable) have some protection by policy, but this is often limited to specific situations (e.g. implementation of GAEC linked to single farm payments under CAP) or the policy instrument is only a guideline or resource rather than a regulation (e.g. Farming for Climate guidance under the Land Use Strategy in the Climate Change Act). There are therefore are no direct regulatory requirements to minimise soil erosion on agricultural land. Post-CAP, these guidelines should be incorporated into national policies, although their efficacy to prevent soil erosion should be reviewed.
• The offsite impacts on drinking water, which have the greatest offsite costs, are protected by various water environment policies (e.g. Water Environment Regulations). However, these focus on preventing eroded soil reaching water courses (e.g. by putting in barriers or buffer strips) and do not offer guidance or requirements to reduce soil erosion at source. Whilst many surface water catchments in Scotland are not abstracted for drinking water, the Water Environment Regulations should be followed to ensure that waters comply with ‘good ecological status’ (reflecting the EU Water Framework Directive) to avoid any adverse impact on the aquatic environment.
• Other large offsite costs are the GHG costs of soil carbon lost from eroded soil (as CO₂) and these are primarily associated with peaty soils (organo-mineral and peat soils) under rough grassland. However, the mis-match in scales between national scale soils data and field-scale IACS data means that there is a chance that unlikely land use/soil combinations such as arable production systems with relatively high erosion rates on peat soils with high probability of erosion will occur in the GIS analysis leading to an overestimate of the soil C losses at a national scale. There are many guidance and advice documents advocating minimising soil carbon loss (e.g. Forestry Standard), however there are no specific regulatory frameworks or polices that directly address carbon loss by erosion, especially in these peaty soil types.
• Under forestry land use, the Forestry Standard offers guidance on soil erosion. This sets out guidance for suitable forest management for minimising soil erosion during forestry operations, but these are not statutory requirements.

Mitigation measures for soil erosion have been reviewed in the Literature Review (Appendix 1) and then characterised in terms of their applicability to Scotland, based on discussions with James Hutton Institute staff (Appendix 11). The current analysis identifies the major contributors to the total costs of soil erosion. Having identified these, mitigation measures can be targeted to combat these losses. For example, if significant costs are incurred from the losses of greenhouse gases associated with erosion processes, measures can be targeted to control these losses. Practices could include: avoiding inversion ploughing; adoption of reduced tillage; covering bare soil at all times e.g. cover cropping, companion cropping, stubbles, precious seasons crop residues; sequestering carbon from the atmosphere through high density, quick growing crops; avoiding drainage of peats and organic soils; etc.

The question arises as to who should pay for implementation of mitigation measures, if deemed necessary (i.e. to reduce the costs of soil erosion), which has policy implications. For example, it could be argued that some on-site benefits of soil protection (control of erosion) are accrued directly by individuals (e.g. farmers or growers through sustained production and market forces), so they should be responsible for the costs of soil protection measures. However, other on-site benefits accrue to society as a whole (such as reduction in CO₂ emissions from eroded soil and the impact on climate change), suggesting government subsidies may be appropriate. Off-site costs of erosion and benefits of soil protection tend to accrue to society as a whole too, again suggesting that governmental support could be appropriate and justified.