Healthy soils, in which natural soil processes function optimally, form the basis of our existence. This dissertation investigated what happens to soil function when a farmer shifts to extensive farming (less fertilizer, greater crop diversity), and shows that how we measure that function matters quite a bit.
In the Ooijpolder, we compared the management and functioning of grasslands managed by farmers who had adopted extensive farming practices with those of conventional and semi-natural grasslands. No two farmers were found to manage their land in exactly the same way. Differences in management practices among the farmers followed a gradient rather than fixed categories such as “conventional” and “extensive.” Along that gradient, three soil measurements were linked to extensification: which fungi are present, how much organic carbon is present, and how quickly plant material is decomposed. Other soil measurements did not show that relationship.
This dissertation also describes a new method for measuring soil life: through odorous compounds released by soil microbes (mVOCs). Sixteen of these compounds were found to have potential as the basis for an initial “soil life sensor.” Finally, the study investigated whether extensification could be accelerated by “grafting” soil from an extensively managed plot onto a conventionally managed plot: this worked in the greenhouse, but showed no significant effect in the field after two years.
In short: the measurement you choose determines what you observe regarding soil functioning, and mVOCs offer a promising new perspective in this regard.
Rosa Boone grew up in the village of Voorst (Gelderland) and, during a geography class, watched the documentary “Groen Goud” about ecosystem restoration. This inspired her to pursue an interdisciplinary bachelor’s degree in Future Planet Studies and later a master’s degree in Earth Sciences at the University of Amsterdam (UvA). During her studies, she developed a particular interest in soil. For her internships, she used a combination of remote sensing and soil measurements to monitor soil processes and ecosystem restoration. In 2021, Rosa began a PhD program at Radboud University as a soil ecologist within the Ooijpolder-Groesbeek Living Lab project. In addition to conducting research, Rosa was actively engaged in building connections with the farming community. Rosa now works at VU University Amsterdam on the interdisciplinary and transdisciplinary Curvebend project. There, she collaborates with researchers from the Netherlands and abroad, as well as local stakeholders, to explore how collective action can help reverse the trend of biodiversity loss.