Soil analysis using cotton underwear: results of the "Proof by Underpants" project

As part of the "Proof by Underpants" project, researchers together with 1,000 volunteers buried over 2,000 pairs of cotton underwear and 12,000 tea bags in various locations: in gardens, fields, meadows, and on lawns. After two months, the objects were retrieved from the soil to analyze the degree of their decomposition. The results showed that the rate of material degradation depends directly on the type of land use.

The most active decomposition of cotton items, reaching 58%, was recorded in private gardens. Experts attribute this to high biological activity provided by the activity of fungi, bacteria, and worms. In contrast, the lowest levels of biological activity were noted on agricultural land, in meadows, and in lawn grass monocultures, which indicates problems with soil fertility and a lack of nutrients.

The team of scientists, led by agroecologists from the University of Zurich, proposed implementing the "Underpants Index" as a tool for monitoring soil condition. According to Marcel van der Heijden, managing soil health is critically important for ensuring the nutrient cycle and ecosystem productivity. However, experts emphasize that the maximum rate of decomposition does not always indicate soil "health." In particular, private gardens often show an excessive concentration of phosphorus, nitrogen, and potassium due to regular fertilizer application. Franz Bender notes that an excessive content of nutrients near natural ecosystems can lead to imbalances and pollution of waterways.

This experiment made it possible to form one of the largest datasets on soil life in Switzerland. Scientists believe that using simple methods, such as the decomposition of cotton fabric or tea bags, helps draw public attention to the problem of topsoil degradation, on which 95 percent of global food production and the conservation of biological diversity depend.