It's a test for healthy soil.
Delaware Farmers Burying Underwear To Test How Healthy Soil Is
There's a good reason why you saw soiled undies at Eco Experience
Soil Your underwear' challenge reaches Oregon
Sonoma's “Soil My Undies Challenge” Going Viral - Sonoma Magazine
Here's Why U.K. Farmers Are Burying Their Underpants in the Ground
The Weird Gardening Hack That Uses A Pair Of Underwear To Test Soil
Soil Your Undies Challenge Natural Resources Conservation Service
The Soil Your Undies Challenge- A Simple Home DIY Test for Soil
Underpants experiments are taking place in Australian paddocks and
Dirt Diaries: Soil Health Campaign Drives Underwear Digs Across Pennsylvania