1,000 Swiss Volunteers Buried Their Underwear for Science

Imagine digging a hole in your backyard, burying a fresh pair of cotton underwear, and calling it science. That's exactly what more than 1,000 Swiss volunteers did in 2021, and the results are transforming how we understand the living soil beneath our feet.

Researchers from the University of Zurich and Agroscope launched the "Proof by Underpants" project to study soil biodiversity in a way everyone could participate in. Volunteers buried over 2,000 pairs of underwear and 12,000 tea bags at roughly 1,000 sites across Switzerland, following the same simple method.

The concept was brilliantly straightforward. The faster the cotton fabric disappeared, the more active and healthy the soil was. Busy communities of earthworms, fungi, and bacteria worked faster to break down the material.

After two months underground, participants dug up their underwear, photographed the remains, and sent samples to the lab. The differences were striking.

Private gardens showed the fastest decomposition, with some underwear nearly vanishing completely. These soils had the highest organic matter and created perfect homes for diverse soil organisms. Lawns showed the slowest breakdown, indicating less biological activity happening below the surface.

Agricultural fields and meadows fell somewhere in between. The findings revealed that how we manage land matters more than almost any other factor in determining soil health.

Professor Marcel van der Heijden explains that healthy, biologically active soil is crucial for fertility and nutrient cycling. Simple practices like keeping soil covered, applying compost, using diverse crop rotations, and reducing chemical fertilizers can dramatically boost soil life.

But faster isn't always better. In forests and some gardens, very rapid decomposition can signal too many nutrients, disrupting natural balance. The underwear test helps people understand when they might be over-fertilizing.

Why This Inspires

This project shows how everyday people can contribute to meaningful scientific discovery. The 240 citizen scientists who participated enough to earn co-authorship on the published study didn't need advanced degrees or expensive equipment. They just needed curiosity and a pair of cotton underwear.

Their collective effort created one of Switzerland's most comprehensive datasets on soil life, something researchers couldn't have achieved alone. In return, volunteers received personalized feedback about their soil, including analysis results and advice for managing their land more sustainably.

The researchers are now proposing an "underwear index" to help make soil health easier for everyone to understand and measure. It's a reminder that protecting the half of Earth's biodiversity living beneath our feet doesn't require complicated science, just simple tools and community effort.

Sometimes the best solutions to big environmental challenges start with burying your underwear in the backyard.