Researchers found that underwear buried in private gardens decomposed the fastest due to high levels of organic matter, while items buried in grasslands degraded the slowest, demonstrating that land use heavily influences soil health.
Soil Biodiversity and the Swiss Underwear Experiment
Earth is home to an immense underground ecosystem where more than half of the world's biodiversity resides. To map this hidden activity across the country, researchers launched a nationwide project in 2021 that relied on public participation.
Participants buried standardized cotton underwear and tea bags at fixed depths, left them underground for two months, and then excavated, photographed, and shipped the remnants back to researchers alongside soil samples. Because soil organisms actively feed on and break down cotton fibers, the physical state of the recovered garments served as a direct indicator of biological activity. Items in some locations degraded into threadbare scraps within 60 days, while others remained nearly intact.
How Land Use Drives Soil Activity
The rate of decomposition depended heavily on how specific plots of land were managed, often outweighing other measured soil properties. According to project findings, private gardens exhibited the fastest decay rates because they typically contained higher concentrations of organic matter that nourished soil microbes. Conversely, grasslands showed the slowest breakdown rates, with agricultural fields and pastures falling in between.
Did you know? Researchers suggest using an “underwear index” in the future to compare soil health across different regions simply by burying and evaluating standardized cotton fabrics.
Nutrient levels, temperature, and moisture also played critical roles in shaping microbial performance. While high nutrient levels in agricultural soils can support robust plant growth, researchers emphasize that rapid decomposition is not always ideal. In natural ecosystems, excessive nutrient buildup can disrupt environmental balances, while cold or dry soils naturally slow down biological processes.
Expanding Science Through Public Participation
By engaging roughly 1,000 citizens to collect samples from about 1,000 distinct locations, the project achieved a geographic scale that a single research team could not have managed alone. Participants gained a firsthand look at the biological health of their own yards, while scientists secured a vast comparative dataset. While this simple cotton-burial method cannot replace rigorous laboratory soil analysis, researchers point out that it successfully highlights the complex, active world operating beneath our feet without requiring heavy laboratory equipment.
Frequently Asked Questions
Why did researchers use cotton underwear for the experiment?
The speed of this decay acts as an easy indicator of local biological activity.
How long were the items left in the ground?
Participants buried the cotton underwear and tea bags for a duration of two months before digging them up for analysis.
Where did the underwear decompose the fastest?
Private gardens recorded the fastest decomposition rates due to high levels of organic matter, whereas grasslands showed the slowest rates.
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