Soil ecologist Wim van der Putten: ‘Developing simple, easily measurable indicators of soil health is going to be an enormous challenge.’ Photo: Perro de Jong, NIOO-KNAW.
Wageningen soil ecologist Wim van der Putten is fascinated by the way the underground drives what happens above ground. ‘Once you understand that, you look at biodiversity in a completely different way.’ Van der Putten stepped down from his Wageningen chair in functional biodiversity on 13 June 2025. (This interview was first published in Bionieuws on 10 February 2023)
‘If our soils are in such poor condition, how is it that we still achieve record harvests of potatoes or sugar beet? That is a question we are often asked, and we call it the soil paradox: because if you look only at crop yields, our soils appear to be doing just fine. We achieve those yields by using the soil as a conduit for nitrogen, phosphate, potassium and other nutrients. It is an extremely one-sided view of soil fertility and tells us nothing about soil health’, says soil ecologist Wim van der Putten (born 1958) of the Netherlands Institute of Ecology (NIOO-KNAW) in Wageningen. He recently published a call, together with five colleagues, for international legislation on soil health (Science, 6 January). He is also closely involved in the Onder het Maaiveld programme, through which the nature organisation IUCN-NL, De Vlinderstichting, Wageningen University & Research and NIOO-KNAW aim to raise knowledge and awareness of the richness and value of healthy soils. In addition, he leads the research project Soilpros – Soil biodiversity analysis for sustainable production systems – which, with €4 million from the NWO Perspective Programme, is working with farmers and businesses to explore how agricultural land can once again become multifunctional.
‘A very quiet drama has unfolded around soil’
‘A very quiet drama has unfolded around soil, with major consequences for biodiversity’, observes Van der Putten, who has also held a special chair in functional biodiversity at Wageningen since 2003. ‘Intensive agriculture treats the soil primarily as a conduit for nutrients, and as a result the soil’s other services – carbon and greenhouse gas storage, suppression of diseases and pests, and water retention and filtration – have fallen completely out of view. This has had major consequences for soil life, which plays a key role in all these processes. And this applies to all intensive agricultural areas across Europe.’ He points here to comparative research carried out in Sweden, England, Greece and the Czech Republic (Global Change Biology, 2015).
FOOD PYRAMID
‘A handful of soil can contain as many as five thousand species and ten billion organisms. The bacterial component of the food web has remained largely intact even in intensively managed soils, but the proportion of soil fungi, protists, worms and other invertebrates has declined sharply. The upper part of the food pyramid has collapsed, and the only organisms you can still count as winners are plant-parasitic nematodes.’
Van der Putten expects the European Union’s Soil Strategy for 2030, backed by legislation, to bring about change. ‘At present, between 60 and 70 per cent of soils are below the health threshold, and Brussels’ ambition is that by 2030 precisely 60 to 70 per cent of soils will be healthy, rising to 100 per cent by 2050. Developing simple, easily measurable indicators of soil health is going to be an enormous challenge. There are many different soil types, and you cannot simply designate a handful of soil-dwelling species as indicators for all soil functions. We hope to develop and roll out measurable, standardised tests for soil biodiversity using eDNA – comparable to the way in which we analyse the health of the human gut microbiome’, says Van der Putten. The IJkcentrum voor de Bodem is playing a pioneering role in developing such reference values for different soil types.
MARRAM GRASS
Van der Putten has experience with applied research. He completed his PhD in 1989 as a Wageningen biologist, working at the biological station Weevers’ Duin in Oostvoorne on dune stabilisation by marram grass. ‘Rijkswaterstaat was particularly pleased with the new cultivation method for marram grass that I developed, by sieving underground stems from the sand using a bulb harvester. It saved them an enormous amount of money in planting marram grass for coastal reinforcement’, says Van der Putten. ‘From a scientific perspective, the important discovery was that the disappearance of marram grass from old dunes is a consequence of the build-up of soil pathogens and parasites.’ It provided a fundamentally new explanation for succession and how the below-ground environment drives above-ground species composition (Nature, 1993). ‘Those interactions between above and below ground were an eye-opener for me too. Once you understand that, you look at biodiversity in a completely different way.’
In follow-up research and field experiments, Van der Putten and a growing group of young soil ecologists uncovered interactions showing that the soil food web plays a key role in the establishment, maintenance and succession of plants (see also: Bionieuws 12, 2021). Knowledge that is now being applied in the Soilpros project to find biological indicators for steering soil health using artificial intelligence and network analyses. ‘This approach should teach us how to restore multifunctionality in agricultural soils.’ In addition, Van der Putten wants to produce a Dutch soil biodiversity atlas, following on from the Global Soil Biodiversity Atlas that he produced together with European colleagues in 2016. ‘It is important to put invisible soil biodiversity visibly on the map. There is now an entire generation of ecologists immersed in the soil. They are not following exactly in my footsteps, but are fortunately finding their own way. It does feel good that soil ecology has now gained so many more feet on the ground.’
(This interview appeared in Bionieuws on 10 February 2023)
See also:
–Farewell lecture Wim van der Putten – WUR website, 13 June 2025
–Intensive land use reduces soil functions – Bionieuws, 2 May 2025
–Biodiversity experiments require a long-term commitment – Bionieuws, 3 July 2021
–The soil paradox – Onder het maaiveld, 10 November 2020
–IJkcentrum Bodem
–Wim van der Putten – NIOO-KNAW website