Full Breakdown
Swiss “Underwear Index” Reveals Soil-Health Variations Across the Country
8/30/2026, 7:46:28 PM
The Underwear Index Experiment
A citizen-science project called “Evidence Underwear” (German: Beweisstück Unterhose) enlisted roughly 1,000 volunteers across Switzerland to bury two pairs of organic-cotton men’s underwear at each site for two months. The initiative, launched in 2021 by the University of Zurich and the federal agricultural research institute Agroscope, aimed to create a simple, large-scale metric for soil-decomposition activity. Results were published in the journal *Plants, People, Planet*.
Method and Participation
Each participant received a kit containing the underwear, twelve teabags, soil-sampling bags, and written instructions. Volunteers selected their own locations—ranging from private gardens and agricultural fields to meadows and lawns—dug vertical holes, placed the underwear side by side, left the synthetic waistbands visible, and positioned six teabags in front of each pair. After two months, they retrieved the garments, photographed them, and sent them with a soil sample to the laboratory. The study ultimately involved more than 2,000 pairs of underwear at about 1,000 sites, and around 240 citizen scientists are listed as co-authors on the paper.
Findings on Soil Activity
Decomposition rates varied markedly with land use. Underwear broke down most rapidly in private gardens, which also showed the highest organic-matter content. Agricultural fields and meadows displayed intermediate rates, while lawns exhibited the slowest degradation. Researchers noted that land-use category explained more of the variation than measured soil properties such as nutrient levels, temperature, and moisture. The study also highlighted that rapid decomposition can signal high fertility but may also indicate excess nutrients, especially in near-natural habitats.
Expert Views and Official Statements
Marcel van der Heijden, agroecologist at the University of Zurich, emphasized that the experiment demonstrates how management practices influence both soil life and quality, underscoring the importance of biologically active soil for ecosystem services.
Implications and Future Applications
The “Underwear Index” offers a low-cost, equipment-free alternative to the traditional Teabag Index, making nationwide soil monitoring feasible through public participation. By providing volunteers with individualized soil-test results and sustainable-land-management advice, the project also aims to raise awareness of soil as a living ecosystem and encourage practices that support soil biodiversity.
