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Cotton underwear buried in garden on left and two disintegrated pairs of under on floor

Soil Your Undies Challenge

Have you ever wondered how healthy your soil is? Take the Soil Your Undies Challenge and find out!

Graphic of people with shovels in field with underwear banner that says Soil Your Undies Challenge

How does it work?  

Just bury a pair of cotton underwear around May-June and dig it back up after at least 60 days. It’s the quick and dirty way to test the microbial activity in your soil. The more the underwear is deteriorated, the healthier your soil!

What are the steps?

Whether you're on crop, range or forestland, the quick and dirty way to test your soil health is by "planting" a pair of new, cotton underwear in the site you're curious about.

1. Plant a pair of new, cotton underwear. Start in May-June since the temperature of the soil is warm enough that the microbes wake up. If you wait too long and it isn't under irrigation it can get too dry and not much happens. 

2. Wait at least 60 days. This gives your soil microbes time to do their magic! 

3. Share your results by sending a “planting” (before) photo and a “harvest” (after) photo along with your location and a little info about your operation (e.g., farm, ranch, garden, high tunnel) to:

You can show your neighbors and other producers just how healthy your soil is. We’ll post your results on our NRCS Montana Twitter!

Woman holding up undies that were buried in garden and lawn
Image on left: 5 weeks buried in a 12 year no-till garden.
Image on right: 5 weeks buried in monoculture of Kentucky Bluegrass fertilized lawn.

Microbial Action!

Your undies won't break down in just any soil. 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.

Soil microbes are your best friends. The hungry microbes in your soil need food, shelter, and variety in order to thrive, just like us!

You can take care of your microbial friends by following these four steps:

1. Avoid soil disturbance wherever and whenever possible.

2. Maximize soil cover with living plants and residue.

3. Maximize biodiversity by growing a variety of plants and managed integration of livestock.

4. Maximize living roots in the soil throughout the year. 

Soil health gauge

Some tips!

  • To plant the undies, use your shovel or spade to slice into the soil about a foot deep. Bend the shovel enough to place the briefs in the space and straighten them out from top to bottom - no one likes bunched undies. This minimizes soil disturbance of the test.
  • When finished planting, elastic waistband is above ground.
  • If it is dry when you bury the briefs, add water to the sites. Use non-treated water (chlorine and other chemicals are designed to kill microbes).
  • Compare briefs buried in different land uses like cropland, rangeland, gardens, hayland, pastures, and forested lands. Compare briefs buried in the same land uses under different management systems such as fields with and without cover crops, with and without spreading manure, with and without no-till seeding history, with and without earth worms.

For more information and questions, please contact NRCS Montana Public Affairs at or call the NRCS Montana State Office at 406-587-6811. 

Learn more about Soil Health in Montana.

Good luck and happy planting!