Scientists wanted to understand how active the organisms living in the soil are and found that the speed of organic material decomposition is most influenced by how a specific piece of land is used and managed. ## Why Scientists Needed Underwear The Proof by Underpants project was launched in 2021 by researchers from the University of Zurich and Agroscope — the federal research center of Switzerland in the field of agriculture. As reported in the official material from the University of Zurich "Buried Underwear Shows Land Use Is Key to Soil Health", the scientists enlisted about 1,000 volunteers who buried more than 2,000 pairs of white cotton underwear in approximately 1,000 locations across the country. Along with the underwear, participants also buried 12,000 tea bags. After two months, all items were to be dug up, photographed, and sent to researchers for analysis along with soil samples.  _Photo: Priska Koller, Agroscope_ Why underwear specifically? Initially, the scientists considered ordinary pieces of cotton fabric and socks, but the unusual format of the experiment turned out to be much more appealing to volunteers. As a result, a large dataset was collected from many regions. ## What Decomposed Underwear Can Tell Us The essence of the experiment was not the underwear itself. Cotton fabric contains organic material that is gradually broken down by bacteria, fungi, earthworms, and other soil inhabitants. The more active the soil organisms are, the faster they decompose the cotton.  _Photo: Gabriela Brändle, Agroscope_ Therefore, the degree of fabric degradation became a kind of indicator of biological activity in the soil. Participants could literally see how much the underwear changed over two months, while scientists had the opportunity to correlate these results with the characteristics of specific plots. The results of the study were published on August 24, 2026, in the scientific journal Plants, People, Planet in the article Soil Health Assessment Using Buried Cotton Underpants with the Help of 1000 Citizen Scientists. ## Where Underwear Disappeared the Fastest The highest decomposition rate was observed in private gardens. It was there that researchers found more organic matter — a suitable environment for earthworms, fungi, bacteria, and other soil organisms.  _Photo: Nicolas Zonvi, UZH_ Cotton decomposed the slowest on lawns. Fields and meadows occupied an intermediate position. It was here that the main result of the study emerged: the type of land use turned out to be the most important factor determining the speed of underwear decomposition. In other words, the differences between gardens, lawns, fields, and meadows explained the results better than most other studied soil characteristics. ## What About Fertilizers The study showed that the speed of decomposition was influenced not only by land use characteristics but also by the chemical properties of the soil, including nutrient content. Rapid cotton decomposition in many cases indicated high biological activity and good nutrient supply in the soil. This can be an advantage for agriculture. However, scientists warn: the faster the underwear decomposes, the healthier the soil — is not a universal rule. As noted by project leader from Agroscope Franz Bender, in natural ecosystems, such as forests, excessively high nutrient concentrations may indicate a disruption of the natural balance. A similar situation can occur in gardens, where overly rapid decomposition may indicate an excess of fertilizers. Therefore, sometimes slower decomposition is not a bad result at all. ## What Else Affects Soil Activity The work of soil organisms is also influenced by environmental conditions. Temperature and humidity are particularly important. If the soil is too cold or dry, microorganisms and other organisms become less active, and decomposition processes slow down. Researchers also note that the state of the soil largely depends on how humans interact with it. Maintaining soil life is aided by a constant plant cover, the addition of compost, diverse crop rotations, and reasonable limits on the use of mineral fertilizers and pesticides. ## Why the Experiment Received the Ig Nobel Prize The unusual project turned out to be so memorable that its authors received the Ig Nobel Prize — an award that honors research that first makes people laugh, and then makes them think. For scientific work, this is quite an appropriate example: the idea of burying thousands of underwear sounds comical, but behind it lies an attempt to create a simple and understandable way to show people what is happening in the soil. Moreover, the participants in the study were not only scientists. Ordinary residents of Switzerland helped collect data from a vast area, turning the experiment into a large-scale citizen science project. ## "Underwear Index" for Soil Assessment Researchers propose using the results of the experiment to create a kind of "underwear index" — a visual way to convey information about the biological activity of the soil. The idea is simple: to show how quickly organic material decomposes in a specific soil, thereby drawing people's attention to what is happening beneath the surface. After all, soil is not just what plants grow on. It stores water, carbon, and nutrients and is a habitat for a vast number of organisms. According to scientists, more than half of the planet's biodiversity is linked to underground ecosystems. ## What the Unusual Experiment Showed The story of the thousands of buried underwear clearly demonstrates that the state of the soil largely depends on how humans use and manage the land. At the same time, scientists urge not to reduce soil health to a single indicator. Rapid cotton decomposition may indicate high biological activity and fertility, but in some ecosystems, it may simultaneously indicate an excess of nutrients. Therefore, the main discovery of the experiment is not that old underwear became a scientific tool. Much more important is that the most unexpectedly apparent method helped make the invisible life of the soil understandable and measurable.
