Soil biodiversity is crucial for a healthy soil, which is crucial for a healthy society. But how can that insight be translated into effective policy on soil? The European Union is currently preparing the first ever piece of international legislation to protect soil health. In Science, a group of scientists led by NIOO's Wim van der Putten outlines some of the challenges the new law will face.
The EU's overall aim is that soils throughout Europe be healthy by 2050. To achieve this, it will soon roll out its European Soil Health Law. It's a major step towards fulfilling the United Nations' Sustainable Development Goals, provided that the effects of soil health protection in one region will be evaluated from a global perspective.
The new law should be binding, and is based on the idea that healthy soils can fulfil a range of different functions. Protecting against diseases, for instance, and helping to mitigate climate change.
In the past, the emphasis was on soil quality, which is largely chemical and physical in focus and mostly used to characterise the status of soil to sustain crop productivity. Soil health, by contrast, takes a more holistic view, being based on the recognition that soils provide multiple ecosystem services in addition to food production, and also that the soil's biological composition plays a critical role.
Struggle for indicators
Until now, most policies to protect soil health lacked such a holistic view. But its inclusion does mean the new law faces major challenges, write NIOO soil expert Wim van der Putten and his international colleagues in their 'Policy Forum' piece in Science. For one thing, even just a handful of soil contains a staggering number of organisms. Letting each piece of land be analysed in depth would simply be too expensive for most land owners.
“To maintain a soil health law, low-cost effective indicators of soil health are needed", says Van der Putten. The EU is proposing a Europe- wide scheme to provide landowners with free do-it-youself soil tests, and that's "a great preliminary step" say the authors. But because soil organisms perform so many different functions, there is no single species that can represent all. This would limit the usefulness of most basic tests.
Another challenge is to find natural soils that can act as a reference. This may be feasible for grassland and woodland, but for agricultural and urban soils there is no gold standard. Also, there are many soil organisms whose existence we don't even know about. And for micro-organisms, the species concept is less clear than it is for plants or animals.
That makes it difficult to determine which soil species can be found where, and whether they are threatened. Consequently, an IUCN-style 'red list' for soil organisms is still a long way away.
Another kind of challenge, say the authors of the article, is to think globally. "Policy", they write, "should focus not only on soils within a nation or union of nations but also on preventing negative footprints on each other’s soils."
Soil health doesn't stop at national borders. Intensive animal farming in industrialised countries, for example, requires the import of feed from other locations. Even with the new law in place, the production and transport of this feed could still degrade soil biodiversity and soil health in both feed-production and feed-consumption locations.
In fact, stricter rules within the EU could even lead to a shift in capacity to other regions, including South-America and Asia, with fewer regulations. "The proposed EU Soil Health Law should motivate other countries and regions to protect their soil health as well", Van der Putten stresses.
Nevertheless it's very positive to see this first soil health law being proposed, and the challenges in no way mean it's dead in the water. One other thing that's necessary to make it a success is 'soil literacy': increased awareness of soil biodiversity by a wide audience. Recent developments have been encouraging, with the Global Soil Biodiversity Atlas and similar projects attracting a great deal of attention.
Van der Putten is also hopeful about the adoption at the COP15 summit in Montreal of the Plan of Action 2020-2030 (.pdf) for the International Initiative for the Conservation and Sustainable Use of Soil Biodiversity. And new scientific techniques including metagenomics and artificial intelligence can help assess soil microbial communities and their functional potential at the scale needed to monitor whether the soil health law is carried out well.
Van der Putten: "Considering the current interest in soil health and the role of soil life in a sustainable society, it should be possible to make the new law a success. After all, a healthy living environment is something we all benefit from in the end."