1,000 Swiss citizens buried underwear to test soil health

The experiment began with a strange parcel of fieldwork: 1,000 Swiss citizens buried cotton underpants in the soil and left them there for two months. The underwear was not the point. It was a simple, shared measuring device in a citizen science project mapping soil health across Switzerland.

When the participants dug the fabric back up, researchers could use its decomposition as an indicator of what was happening underground. Decomposition breaks complex organic matter—leaves, wood and even cadavers—into simpler organic and inorganic compounds, releasing carbon dioxide and nutrients. Decomposition rates are one key indicator of soil health.

The results were reported in Plants People Planet. Marcel van der Heijden, an agroecologist at the University of Zurich and a paper co-author, said the findings showed that how soil is managed can significantly affect both soil life and soil quality. The study addresses a gap: large national decomposition studies comparing different land uses have been relatively uncommon, while smaller studies have already shown that human use of a site can influence biological diversity.

And so what, concretely? The project used a shared piece of cotton and many participants to map soil health across Switzerland. The source links biologically active soil to fertility, nutrient cycling and other ecosystem services.

The limits are clear. Soil health has been declining worldwide, and the source describes decomposition as one indicator of soil health. Still, the Swiss project shows how an ordinary household object and a large group of citizens can make an underground process visible at country scale.