Picture a researcher asking you, with a completely straight face, to bury a pair of cotton underwear in your backyard and forget about it for two months. This isn’t a prank or a college dare. It’s exactly what more than 1,000 volunteers across Switzerland have done, as part of a citizen science project. The name says it all: “Proof by Underpants” (“Beweisstück Unterhose” in German).
The University of Zurich (UZH), together with Agroscope, Switzerland’s federal center for agricultural research, runs the experiment. It isn’t chasing dirty laundry for laughs — it’s mapping the health of the country’s soils, one buried pair of cotton underwear at a time.
Why buried cotton underwear instead of a lab sensor?
The logic is smarter than it sounds. Cotton is almost pure cellulose, the same plant material that soil microorganisms naturally break down. That includes bacteria, fungi, and all the tiny creatures living beneath our feet. Therefore, the faster a buried cotton garment disappears, the more biologically active that soil is. In fact, it’s a homemade twist on an established scientific method, the “Tea Bag Index,” which uses tea bags for the same purpose. Still, this version makes for much funnier photos.
Starting in 2021, participants buried more than 2,000 pairs of cotton underwear and 12,000 tea bags at roughly 1,000 locations across Switzerland. Those locations included private gardens, farmland, mountain meadows, and manicured urban lawns. Two months later, each volunteer dug up their garment and photographed it (some photos are, let’s say, very eloquent). They then sent the remains along with soil samples to UZH and Agroscope labs for analysis.
The verdict: gardens win, perfect lawns lose
Published in the scientific journal Plants, People, Planet, the results confirm something anyone with a vegetable patch probably already suspected: how we use land almost entirely determines its biological vitality.
- Private gardens showed the fastest decomposition of all — loose soil packed with compost and varied organic matter is basically a buffet for microorganisms.
- Farmland and meadows landed in the middle, with noticeable but less intense biological activity.
- Manicured lawns — the magazine-cover kind, mowed on schedule and watered daily — showed, by a clear margin, the least decomposition of all.
The explanation makes sense once you think about it. An ornamental lawn is often a compacted monoculture, worn down by constant foot traffic, with few different root systems and frequently treated with products that don’t exactly help soil biodiversity. Meanwhile, a “messy” garden, full of different plants, plant debris, and turned-over soil, offers the opposite: food and shelter for a much richer microbial community.
The researchers themselves note an important caveat. However, faster decomposition isn’t automatically “better” in absolute terms, since it depends on the ecosystem and what a given plot of land is actually meant for. Still, as a comparative measure of biological activity, the experiment worked beautifully. Moreover, it produced the most detailed map to date of the hidden life under Swiss soil.
Science made by, and for, everyday people
Perhaps the most striking part isn’t the result itself but who gets credit for it. Around 240 of the volunteers who buried their cotton underwear are listed as co-authors on the published scientific paper. That’s an unusual honor for someone whose main contribution was sticking a garment in the ground and waiting patiently. You can read the full study details on the University of Zurich’s official website.
So next time you look at your garden, or the lawn at the local park, remember this: there’s an entire ecosystem working away in silence underneath. It’s quite literally waiting for someone to bury a piece of clothing to prove it.