This Research Topic (RT) is related to the Eurosoil 2021 conference, focusing on the contributions of soil science to reach the targets of the UN Sustainable Development Goals SDG 6 (Clean Water and Sanitation) and SDG 15 (Life on Land). The overall aim of SDG 15 is to sustainably use and manage terrestrial ecosystems and to halt and reverse land degradation. The particular role of forests, wetlands, and mountains as water-related ecosystems makes their protection and restoration also a target of SDG 6, with the overall aim of improving the quality of drinking water resources through integrated water-resources management.

In this RT, we want to highlight the role of soil functions to achieve these targets. Soil functions (SF) are related to SDGs via their contributions to respective ecosystem services (ES, Keesstra et al., 2016). Soils per se are multifunctional and contribute to various ES. However, this multifunctionality is threatened by two main factors, leading to degradation. Firstly, the optimization and exploitation of soils for productivity compromises other SF such as water filtration, nutrient balance, C pool regulation and habitat provision (Kopittke et al., 2021). Secondly the changing climate, in particular rising temperatures and more frequent extreme events (droughts, heavy rainfalls), affects SF directly and indirectly (Hamidov et al., 2018).

The understanding of SF and how they can be improved and maintained sustainably, how they are affected by and can be made resilient against disturbances, and how they can be restored if impaired, is key to locally adapted land-use management (Hamidov et al., 2018), e.g., for use in conservation and integrated agricultural systems (Stavi et al., 2016), or for successful nature-based catchment restoration (Keesstra et al., 2018). The quantification of SF relies on sound relations with measurable state variables and properties (e.g., Greiner et al., 2017; Vogel et al., 2019), however many of these relationships are not well established yet (Lorenz et al., 2019). The overall capacity of soils to fulfil their functions and thus to contribute to ES can be summarized in the term soil quality or soil health (e.g., Bünemann et al., 2018; Bonfante et al., 2020; Lehmann et al., 2020).

In this context, the contributions to this RT deal with various issues in quantitatively assessing SF on a local basis. They can be grouped into 1) methodological improvements of measurements and monitoring, 2) testing indicators and indices for assessment of soil degradation and restoration success, and 3) policy frameworks and case studies related to land management and soil health.