6. Outlook
Science plays an important part in the search, under prevailing pedo-climatic conditions (Fig. 1), for indicators of the structural and process aspects of soil functioning that mediate the delivery of soilbased ecosystem services deemed important by actors and other stakeholders who exert(ed) pressures on the soil through land use and soil threats. The key terms here are ‘actors’ and ‘stakeholders’. Terms such as ‘soil function’, ‘ecosystem service’ and, indeed, ‘soil quality’, are boundary concepts, i.e. concepts that enable researchers from different disciplines, policy-makers, and other stakeholders to develop a common language and integrate and derive knowledge relevant to their field (Schleyer et al., 2017). Beyond scientists, those who have an immediate stake in soil quality are land managers, i.e. farmers, managers of nature conservation areas, roadsides, banks of waterways and urban green areas, and the public at large. As soil quality management is also about societal negotiation in the face of unavoidable trade-offs between various soil uses, the very development of soil quality indicator schemes will benefit from the involvement of actors and other stakeholders with a view to implement adaptive land use and management (Barrios et al., 2006, 2012).
Although, clearly, soil quality is not merely a natural science topic, in most of the reviewed assessment schemes farmers/land managers did not play a leading role. We suggest that intimate involvement of end users is a major point of attention, but it may still not lead to full implementation of the results. For example, in the Illinois Soil Quality Initiative, where farmers were involved in the development of soil quality assessment schemes, they were constrained in the necessary implementation of the results by socio-economic factors (Wander et al., 2002). Clearly, other actors play an important part. Industries that ultimately also depend on the soil, will be (come) important actors, too, such as food, fibre and fuel industries, and electricity production, manufacturing and fashion industries (Davies, 2017). Their interest is in sustained resource supply, which is at stake because of ongoing loss of soil functionality and increased variability in harvests and water supply associated with global climate change, partly induced by unsustainable land use and management. Land managers, industries and, indeed, investors and insurance companies and the public sector at large are increasingly aware of the associated monetary and societal costs and, vice versa, they understand the urgency of adaptive land management and re-design in the framework of food systems (Foresight, 2011) and a fossil-free and circular economy (Rockström et al., 2016).
