Soil biodiversity is crucial for healthy soils, on which we all depend for food, human health, aboveground biodiversity, and climate control. It is well known that land use intensification, climate change, environmental pollution, and mining activities degrade soil biodiversity. However, most current and intended policies on soil protection not only lack a holistic view on how biological, physical, and chemical components of soil health are integrated but also overlook how soils across national borders and continents are connected by human activities. The challenge is to use recent advancements in understanding the distribution and functional roles of soil biodiversity in developing policy on restoring and protecting soil health across borders. Thus, policy should focus not only on soils within a nation or union of nations but also on preventing negative footprints on each other’s soils.
Numerous factors—such as urbanization, automation, disease outbreaks, natural disasters, and even wars—influence how land is used, which affects the capacity of soils to perform multiple functions, also called soil health (1). Searching for sustainable land use while providing food and feed for a more demanding population and dealing with growing demands on land for multiple other functions requires insights into the many factors that influence land use. Often, land use options are considered trade-offs, and the challenge is to search for win-win options, for example, climate change mitigation by biodiversity restoration. A transdisciplinary approach may help to understand possibilities and trade-offs to achieve a more sustainable society (2). Although an awareness that healthy soils are the basis of a healthy society is growing, anchoring this view into policy is still a challenge.
Soil protection requires an integrated legal framework to address the multitude of processes that are involved in land degradation, but most existing soil laws that should protect soils now focus on single issues, such as desertification or soil contamination. Moreover, soil protection laws are mostly national (3), although soil protection does not stop at national frontiers. For instance, current climate change caused by poor land use and industrialization outside sub-Arctic regions causes melting of the permafrost, which in turn exacerbates climate change through the release of carbon dioxide and methane to the atmosphere.
Although it is widely acknowledged that plants, birds, butterflies, and many other animal species need to be protected, little explicit attention exists for protecting soil biodiversity (4). The European Union (EU) Soil Strategy for 2030 (5) has been set up to combat declining soil health in Europe and beyond. The ambition is to have healthy soils in the entirety of Europe by 2050. An important aspect of this ambition is that the EU is planning to propose a binding European Soil Health Law in 2023. To the best of our knowledge, this is the first and most inclusive soil health protection law that recognizes the ecosystem services provided by healthy soils and the need to protect those services for future generations. Proposing a soil health law is an important step toward a sustainable society; however, the real challenge is to make it work.
To make the EU’s Soil Health Law operational, soil health needs to be measurable. Different from soil quality, which is largely chemical in focus and mostly used to characterize the status of soil to sustain crop productivity, soil health is a more holistic concept (6). It is based on the recognition of the ecosystem services that soils provide. As defined in the EU soil strategy, soils are healthy when they are in good chemical, biological, and physical condition and are able to continuously provide as many of the ecosystem services as possible. Soil health addresses the sustainability goals set by the United Nations (UN), which have been adopted by many countries. However, finding effective, easy-to-measure indicators for soil health is challenging, because there is no one-size-fits-all indicator for all circumstances, just as in the case of soil quality (7).