In what might be the world’s most unusual soil survey, everyday citizens became researchers by burying ordinary cotton underpants and digging them up two months later. The project, led by agroecologist Marcel van der Heijden of the University of Zurich, enlisted participants from 25 countries, with an initial focus on 1,000 Swiss volunteers. The underwear served as a standardized organic material: the more decomposed it emerged, the more biologically active the soil.
“Our results show that how soil is managed can significantly affect both soil life and soil quality,” van der Heijden said. “Healthy, biologically active soil is crucial for fertility, nutrient cycling and many other ecosystem services.”
Soil health has been declining worldwide, threatening food security and ecosystem function. Decomposition rates of organic matter — leaves, wood, even cadavers — are a key indicator of biological activity, but large-scale studies across different land use types have been rare. This project bypassed that gap by turning citizens into data collectors, burying standardized cotton strips (in this case, underpants) and recording the degree of decomposition.
The method builds on earlier small-scale research that showed human land use — agriculture, forestry, urban development — alters soil biodiversity. By using a cheap, familiar object, the study generated data at a scale previously unobtainable through professional scientists alone.
The paper also highlights the potential for such citizen science efforts to monitor soil health globally, especially in regions with limited laboratory access. The findings are expected to inform agricultural policies and land management practices aimed at preserving and restoring soil quality.