'Soiling' Your Underwear — For Science!

A team of Swiss researchers had an unusual request for 1,000 citizen scientists. They wanted them to soil their underwear, please and thank you.

The volunteers happily agreed. They buried their cotton undies in the soil near their homes. They tossed 12,000 tea bags in, too. The goal: to use the underwear cloth and tea bags as a measuring stick for soil quality.

The formula was straightforward. The more a buried pair of undies was eaten through by bacteria, bugs, and other dirt dwellers, the “healthier” the soil. That's because more underwear-munching organisms generally means a plot higher in nutrients and lower in toxins. If a pair was still in good shape when it was dug up, it likely meant that the organisms couldn't survive in the soil. In a few cases, the team even identified over-eaten underwear. They were a sign that perhaps the dirt had been over-fertilized.

The goal, researchers say, is to capture a picture of soil quality across Switzerland. The underwear can help identify where humans have had the most impact on the ground around them. The team concluded that the healthiest soil was found in private gardens. That was followed by cropland and grasslands. The least-healthy soil was found in lawns. Researchers suggested that lawns may suffer from over-mowing and harsh chemical use. But they didn’t pinpoint a single cause.

Based on the success of their test, the team proposed a new “Underpants Index” to test soil quality moving forward. And as for why they chose underwear? It’s just more fun, they said.

Reflect: If you could turn any everyday habit into a science experiment, what would you want to find out?

Photo of decomposed underwear and citizen scientists courtesy Bender, S. F., Bürge, D., Bragazza, L., Knop, E., Masson, S., Peter, N., Demarmels, R., Mueller, D., Imhof, A., Viviani, P., Bieri, A., Liebisch, F., Geisen, S., Hautier, Y., Panagos, P., Garcia-Palacios, P., Goberna, M., Johnson, D., Jöhr, S., … van der Heijden, M. G. A. (2026). Soil health assessment using buried cotton underpants with the help of 1000 citizen scientists. Plants, People, Planet, 1–19.