03/09/2026
Soils ain’t Soils (IYKYK)
Scientists across Switzerland just gave soil science its strangest experiment yet, and it turned out to be one of the most useful ones in years.
In 2021, researchers from the University of Zurich and Agroscope, Switzerland's federal center for agricultural research, launched a project they called "Proof by Underpants." Around 1,000 volunteers, roughly half of them farmers, were mailed a simple package: two pairs of clean cotton underwear, twelve teabags, and a bag for collecting soil samples.
Their instructions were exactly as odd as they sound. Dig a hole, take a soil sample, bury a pair of underwear alongside six teabags, then walk away and let nature do the rest.
The science behind it is far more serious than the method suggests. One of the clearest signs of healthy, biologically active soil is how quickly it breaks down organic matter. Researchers have long used something called the Tea Bag Index to measure this, but it requires precise lab equipment like fine-scale balances, which limits how many people can take part.
Cotton, on the other hand, is easy to bury, easy to dig up, and easy for anyone to look at and understand. So the team decided to combine both methods and see what the public could help them discover.
Participants dug up their first pair of underwear after thirty days and the second after sixty, photographing the results before mailing everything to the lab along with their soil samples. In total, more than 2,000 pairs of cotton underwear and 12,000 teabags were buried at close to 1,000 locations spanning every region of Switzerland, creating one of the most complete datasets on soil life the country has ever produced.
The results, published in the journal Plants, People, Planet, showed that land use mattered more than almost anything else. Underwear buried in private gardens decomposed fastest, aligning with soil tests that found the highest levels of organic matter and the most thriving populations of earthworms, fungi, and bacteria.
Lawns told the opposite story, showing the least biological activity of any site type, while farmland and meadows landed somewhere in the middle. When compared directly against the scientifically established Tea Bag Index, the humble underwear performed almost as well, officially earning the nickname "the underwear index."
Perhaps the most striking detail is who gets credit for the discovery. Around 240 citizen scientists are listed as co-authors on the published paper, an unusually high number for peer-reviewed research and a rare case of ordinary volunteers shaping science from the ground up, quite literally.
Soil rarely gets much attention, yet it stores water, carbon, and nutrients, and is home to more than half of all biodiversity on Earth. This quietly brilliant experiment proved that sometimes the simplest tools, even a pair of underwear, can reveal the health of an entire ecosystem hiding just beneath our feet.
