Close-up of man's hands holding healthy soil

“Soil Your Undies” sounds like the latest, grossest internet challenge to make the social media rounds. But it’s actually a chance to get your hands dirty with a bit of citizen science. It’s a fun summer science project for the kids to learn about soil health. It could even help you make your garden grow a little lusher.

Soil Your Undies

The “Soil Your Undies” challenge is simple, and nothing like what you’re probably thinking. The challenge is simply to bury a new pair of tighty-whities and dig them up eight weeks later. It’s an easy test of soil health based on the fact that cotton is biodegradable. In healthy soil, there won’t be much more than the elastic waistband of the underpants left after eight weeks. But in soil where the biome is weak, the (washed) underwear is still wearable after two months underground.

Soil erosion and the loss of healthy topsoil are among the top environmental issues affecting farmers around the world. The “Soil Your Undies” challenge originated in Oregon as a project between farmers and their local Conservation Districts as a way to get the public interested in soil health.

Corey Miller, a wheat farmer in Oregon, took the Soil Your Undies Challenge and discovered the richness of his no-till soil:

Oregon Undies Take Off Down Under

Almost immediately, Australian agriculturists and educators hopped on the pants-wagon, and the challenge took off down under. In most parts of the world, people leave a bit of elastic sticking out of the ground to mark their test site. But in Australia, the buried undies kept disappearing (kangaroos have been blamed) so down there they bury their samples completely. More than 400 farms and schools had participated in the challenge by April 2021. There are plans to roll out the school program nationwide.

“Soil Your Undies” is easier and a lot more fun than taking scientific soil samples and reading soil chemistry test results. It’s also a simple way to illustrate the principle of biodegradation for kids. But surprisingly, it has actually led to meaningful changes. Some farmers who participated in the challenge have changed their land management methods to become more sustainable. If commercial farmers can be convinced to change their ways with this simple experiment, it could be just as useful for homeowners who think they need to spray for every bug.

Plant Your Pants

Bury your tighty-whities under about 3 inches of your garden’s topsoil. Assuming you don’t have a kangaroo problem, you can leave a bit of the waistband sticking out to mark the burial site. But using a creatively labeled plant marker might be more fun anyway. Wait two months, then dig them up and take a picture to compare your results with those that have been tracked in North America and Australia.

If you try this at home, make sure the underwear is 100% cotton. Polyester will not degrade in two months regardless of soil health. If you accidentally use a cotton blend, you’ll be illuminating another environmental issue – the need for sustainable underwear (and other clothing) that won’t live forever in a landfill.

By Gemma Alexander

Gemma Alexander has an M.S. in urban horticulture and a backyard filled with native plants. After working in a genetics laboratory and at a landfill, she now writes about the environment, the arts and family. See more of her writing here.