Norm Lamothe and his family run a 500-acre farm outside of Peterborough, Ontario.
In 2015, the farmer heard about a new campaign from the Soil Conservation Council of Canada called “Soil Your Undies.” Like many regional farmers, he was intrigued by the experiment. It involved burying a pair of underpants, waiting a few months, and then digging them back up again.
The attention-grabbing campaign was an easy way for farmers to measure their soil health. Agricultural experts said discolored and “broken down” underwear indicated high microbial activity levels. Simply put, the dirtier the underwear, the healthier the soil.
When Lamothe dug up his underwear, he was disappointed to see that his white Hanes were still in pretty good shape.
“That’s really what started my journey down the soil health path,” Lamothe told The Narwhal. “Much to our chagrin, they were completely intact.”
To get his soil back on track, Lamothe joined peer groups like the Ontario Soil Network and Farmers for Climate Solutions.
With their guidance, Lamothe began rotating crops, including corn, soybeans, winter wheat, and oats — double the variety he once kept, because soil health largely depends on keeping a diverse range of crops in rotation. He also grew hay to prevent erosion and help “anchor” the soil.
Then, in 2022, he brought in a flock of sheep to graze the hay, and their manure reintroduced much-needed nutrients back into the earth.
A decade after Lamothe first “soiled his undies,” the farmer tried the experiment again.
They were much more tattered.
“Whether the change came from our practices or differing weather conditions is up for debate, but certainly we saw we had microbial activity,” Lamothe told The Narwhal, while standing in front of the pair of underwear framed in his office. “[It makes] a nice conversation piece with people in here wondering why there is underwear on the wall.”
Versions of the “Soil Your Undies” campaign have taken root around the world. The United States Department of Agriculture even has an official guide for farmers and gardeners on its website.
“Your undies won’t break down in just any soil,” the Department’s Natural Resources Conservation Service advised. “Healthy soil contains billions of microbes that consume the cotton. In fact, one teaspoon of healthy soil contains more microbes than there are people on the planet. In addition to chowing down on organic matter like cotton, they also help soil resist erosion, cycle nutrients, and store water.”
In 2021, researchers at Agroscope, the Swiss federal center of excellence for agricultural research, joined with University of Zurich scientists and tasked 1,000 volunteers with burying their cotton underpants across Switzerland to measure different soil sites for a citizen science project called “Proof by Underpants.”
In the study, the volunteers buried more than 2,000 pairs of underwear and 12,000 tea bags at nearly 1,000 sites across Switzerland.
After two months, participants dug them up again and sent the undies — and their accompanying soil samples — to the UZH lab.
Five years later, on August 26, the researchers finally published their findings. They revealed that private gardens had the fastest decomposition rate, while lawns had the slowest. Agricultural fields and meadows ranked in between.
“Our results show that how soil is managed can significantly affect both soil life and soil quality,” said co-study leader Marcel van der Heijden, a professor of agroecology at UZH. “Healthy, biologically active soil is crucial for fertility, nutrient cycling, and many other ecosystem services.”
The “Proof by Underpants” project was a win-win: Swiss researchers gained valuable insight into soil samples across the country, and participants received personalized feedback on how to manage their soil more sustainably.
“Overall, this project demonstrates that underpants can serve as a simple and easy-to-interpret tool, providing informative insights into the state of soils,” the researchers wrote in the study, which was published in the scientific journal Plants, People, Planet.
“Moreover, they are perfectly suited to raise attention in society for soil. We propose the ‘Underpants Index’ as an accessible, engaging method to assess soil decomposition processes and soil fertility and raise public awareness for soil as a vital, yet threatened resource.”
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Featured Image: Gabriela Brändle/Agroscope
