Biological processes underpinning soil ecosystem services Methods Preliminary assessment A summary report, Soil Ecosystem Services: the current status and research priorities (Paterson, Glies, Yeluripati & Neilson, 2022) was completed, identifying knowledge-gaps with respect to biologically mediated processes underpinning soil ecosystem services. This report also identified research within the current RESAS Strategic Research Programme contributing to understanding of soil ecosystem services, and how this research links to current policy for soil governance in Scotland. Experimental approach Soils representing a diversity of classifications across cultivated land in Scotland were identified, including long-term experimental sites, where land use and management are known and supported by existing monitoring data. A set of approaches to quantify soil biological functions were applied, focusing on processes underpinning greenhouse gas fluxes, nutrient cycling, crop productivity and nitrogen leaching. The biological functions were selected, both for their direct relevance to soil ecosystem services, and as functions that are represented in biogeochemical models (i.e., the data will support refinement of these models). Results Example of soil functional analysis: Balruddery Centre for Sustainable Cropping Sustainable management, reduced tillage and application of organic amendments to substitute for mineral fertilisers, significantly affected microbial community abundance and composition, strongly impacting the physiological capacity of the soil microbiome to utilize a diversity of organic compounds (Fig. 1). Eric Paterson and Clare Cameron The James Hutton Institute, Craigiebuckler, Aberdeen Email: eric.paterson@hutton.ac.uk Introduction • Soil is a fundamental resource supporting delivery of ecosystem services underpinning societal, environmental and economic benefits. • Historically, these benefits have been linked closely to soils’ capacity to sustainably support plant primary production for food, fibre, and fuel, thereby supporting human life and activities. • These provisioning services remain vital, particularly in the context of increasing global populations, a changing climate and competing pressures on land use. However, a host of other services that soils provide are now recognised to underpin environmental and cultural services that need to be considered in management and policy decisions relating to soils and land use. • The soils of Scotland are highly diverse, shaped by climate and their underlying geology, meaning that the ecosystem services that they can potentially support is variable. • Management of soils for single ecosystem services (e.g., greenhouse gas mitigation) has consequences for others (e.g., food production), and understanding these potential trade-offs, across diverse soils, is a focus of this research. Conclusions  The desk review of existing knowledge on soil ecosystem services identified successful use of soil properties to predict services that are primarily controlled by physico-chemical processes (e.g., resistance to erosion, water infiltration), but that prediction of biologically-driven functions (e.g., greenhouse gas fluxes, nutrient cycling), is more difficult, particularly in the context of dynamic changes associated with management practices.  The soil functional analyses identified strong soil-type effects on biological processes, and that for a single soil, management has a significant impact on the capacity of that soil to mediate processes underpinning greenhouse gas fluxes, element cycling, plant productivity and nutrient retention. Figure 1: Canonical Analysis of Principal Coordinates (CAP) of soil microbial community physiological diversity (MicroRespTM) for conventional (CON) and sustainable (SUS) management practices. These impacts of sustainable management practices on microbial communities were associated with significant effects on soil functions affecting nitrogen availabil