Review Classification and valuation of soil ecosystem services Jón Örvar G. Jónsson ⁎, Brynhildur Davíðsdóttir Environment and Natural Resources, University of Iceland, Gimli, Sæmundargata 2, Reykjavík, Iceland abstract article info Article history: Received 24 March 2014 Received in revised form 26 February 2016 Accepted 28 February 2016 Available online xxxx Soil ecosystem services (ES) provide multiple benefits to humans but to date no consensus has formed on a com- prehensive framework for their classification and economic valuation, and therefore a systematic approach has not been developed to evaluate their importance. We present a literature review of soil ES and functions, the eco- nomic methods that have been used to value them, and values that have been derived from various studies under different type of land use. We illustrate how recent developments in the field of Earth Critical Zone research are contributing to the development of soil ES valuation techniques within the ES framework. These developments have further underpinned the necessity to include the multiple aspects of soils in ES frameworks because of their fundamental roles in ecosystem functionality and vitality. We provide examples on how soil ES can be clas- sified and valued using standard economic methods and established analysis frameworks. We show how signif- icant economic value is derived from soil ES and thus highlight the economic losses associated with soil degradation. Furthermore, we also demonstrate the need to develop a comprehensive framework for the eco- nomic assessment of soil ecosystem services in order to better inform decision-making at various levels of gov- ernance regarding land use and management. © 2016 Elsevier B.V. All rights reserved. Keywords: Soil ecosystem services (ES) Soil natural capital Economic valuation Earth Critical Zone Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 2. Ecosystem services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.1. Ecosystem service classification schemes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.2. Earth's Critical Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 2.3. SoilTrEC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 2.4. Soil and Earth's Critical Zone . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 3. Frameworks for soil ES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4. Soil ES and economic valuation studies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 4.1. Value in economics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 4.2. Valuation tools . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4.3. Valuing soil ES: reviewing values from the literature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4.3.1. Support functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.3.2. Regulating services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30 4.3.3. Provisioning services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4.3.4. Cultural services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4.4. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 5. Concluding discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 Appendix A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37 1. Introduction Soil is one of the more species-rich habitats of terrestrial ecosystems and its functions include biomass production, maintaining nutrient bal- ance, chemical recycling and water storage to name a few (Blum, 2005). Agricultural Systems 145 (2016) 24–38 ⁎ Corresponding author at: Environment and Natural Resources, University of Iceland, Gimli, Sæmundargötu 2, IS-101 Reykjavík, Iceland. E-mail address: jog44@hi.is (J.Ö.G. Jónsson). http://dx.doi.org/10.1016/j.agsy.2016.02.010 0308-521X/© 2016 Elsevier B.V. All rights reserved. Contents lists available at ScienceDirect Agricultural Systems journal homepage: www.elsevier.com/locate/agsy