The Land Capability for Agriculture: building a tool to enable climate change assessments

The Land Capability for Agriculture (LCA) classification for Scotland has been used since the 1980s to inform decision-making on land use management, planning and valuation.

This report explores the potential for a new research tool to estimate land capability under future climatic conditions – the Land Capability of Scotland research platform. Development in this project has been based on the original LCA guidelines. The platform is a set of computing tools (not PC based) for data integration, calculation, analysis, mapping and visualisation, allowing models to be run to estimate land capability constraints and generate digital maps.

The Land Capability research platform is designed to be a ‘risk and opportunities assessment’ tool operated by researchers; the Land Capability of Scotland research platform does not replace the existing published LCA classifications.

The platform has initially been developed to produce estimates of Land Capability for Agriculture under different climate change projections and has further potential to support research on a broad range of land uses and benefits, such as forestry and ecosystem services.

Results

• The original LCA guide has been successfully coded and computing structures implemented, integrating multiple spatial data sets and modelling tools to estimate the individual constraints that determine the LCA and its overall classification.
• A key challenge is the ability to model soil water balance appropriately. A soil water balance model was implemented within the platform, but further work is required to better calibrate the model and validate the estimates. 
• Initial analysis between two baseline periods indicates that climate change has already altered land capability and is likely to further impact it in both positive and negative ways in the future. 
• Reduced water availability is likely to be a key determining factor. Initial analysis suggests that soils, especially those with a low water holding capacity, are likely to become drier and with greater frequency. 
• This implies an increased risk of crops, grassland and vegetation experiencing difficulties in accessing water. The LCA and constraint maps indicate where this may occur.
• There is a substantial risk that land currently classed as prime agricultural land (classes 1 – 3.1) may experience reduced production capability due to dry soils in an increasing number of years with drought conditions.
• Conversely, potentially areas such as the north-west Highlands may experience increased precipitation totals in some years, meaning soils there becoming wetter.
• There is likely to be increased annual variability in land capability associated with increasing climatic variability and extreme events, such as wet seasons or years followed by dry ones.
• The platform development has been a ‘learning by doing’ iterative process, and further improvements are possible. The research platform will continue to be used and developed in the Scottish Government’s 2022-2027 Strategic Research Programme.