A soil can host many species without functioning in the same way as its neighbour. This is the difference the French SolsVivants programme aims to understand better: beyond listing organisms, how do their relationships influence water, organic matter and nutrients?
The programme’s scientific launch seminar takes place from 4 to 6 November 2026 in Angers. Co-led by the CNRS and INRAE, the programme has €9 million over five years. Its name describes research that is just beginning, with questions and protocols still to be developed. It should therefore not be seen as the announcement of a technique already proven to restore any kind of land.
Beneath our feet, relationships as well as species
Soil biodiversity includes organisms of many different sizes. Bacteria, fungi and animals contribute to activities that combine: decomposing organic matter, transforming nutrients, changing soil structure and influencing the movement of water.
The FAO describes these organisms as major players in nutrient recycling, the fate of carbon and the physical functioning of soils. Their role concerns natural environments as well as agricultural systems. Soil is therefore not simply a store of material in which roots grow: it is also an environment alive with biological activity.
Earthworms offer a visible example of this life, but they do not represent it in its entirety. Their presence alone does not provide a complete diagnosis. Observing an animal and assessing how an environment functions are two different levels of information. It is precisely this step from presence to function that interests researchers.
Why an inventory is not enough
In an interview published by the CNRS, Jérôme Mathieu explains that inventory methods are improving, particularly thanks to environmental DNA. They make it possible to identify the organisms present more effectively. However, predicting a soil’s activities from this list remains difficult.
The hypothesis highlighted by the programme’s leaders concerns networks of interactions. Living things feed, compete and cooperate; they also transform the conditions in which other organisms live. Counting species does not automatically describe these relationships.
A so-called ‘trophic’ interaction concerns feeding. A ‘non-trophic’ interaction does not directly involve eating or being eaten. Bringing these two dimensions together should make it possible to study a more complete network than the food chain alone. The question then becomes: which relationships explain a given function, in a given environment and under particular constraints?
Two projects to link living organisms to soil functions
SolsVivants is organising its work around two focused projects. The first looks at networks of interactions. The second examines their role in soils’ capacity to fulfil several functions, which researchers call their ‘multifunctionality’.
The programme distinguishes, in particular, two sets of processes: soil structure and the transfer of water, gases or particles; and the transformations involved in the cycles of carbon, nitrogen, phosphorus and other nutrients. This approach avoids reducing soil health to a single measurement or use.
The work is also intended to bring together observations and models, research in temperate and tropical environments, and scenarios of environmental change. The aim is to understand how biological relationships translate into measurable functioning. Models will be useful if they account for the diversity of situations, rather than offering the same answer everywhere.
What to expect from the results
For a farmer, forester or land manager, the practical question is not only how many organisms live on a piece of land. It is also about understanding which functions are being performed, which are deteriorating and how land use plays a part.
The programme aims to shed light on these questions. Knowledge still has to be produced and then tested against other findings: the launch does not yet provide a list of validated practices or a ready-to-use universal indicator. The results will need to specify the environments studied and the conditions under which a conclusion can be applied elsewhere.
The challenge is to make underground life easier to understand without oversimplifying it. A chemical measurement, a survey of organisms and an observation of water infiltration do not tell exactly the same story. Bringing them into dialogue can help us understand what a soil actually does, and why.
Illustrative photograph: an earthworm observed in Plužna, Slovenia; this is not a site in the SolsVivants programme.
