Who knew soiled undies could be so interesting?

By Teresa Matteson | July 24, 2019


Soiled Undies 1_2
Decomposed undies #1 and #2 indicate healthy microbial activity in LBCC farm soil.

This past year, Oregon NRCS has challenged growers to test their soil health using a new method, the Soil Your Undies Challenge! Active soil microbes are hard at work in healthy soil, but those little buggers are not easy to directly measure. Indirectly, you can track the rate of decomposition of cotton fabric as evidence that the microbes are alive and feeding on organic matter. To support the challenge, Benton SWCD helped distribute several pair of XL white, cotton undies to growers around the county.

The challenge results are beginning to trickle in.

Dr. Hathai Sangsupan, LBCC soil science instructor, accepted the Soil Your Undies challenge to give her students a memorable soil health, nutrient cycling lesson. On April 19th, they planted two pair near the LBCC organic farm, and a third pair was placed in a leaf pile. The undies were harvested on June 7th.

#3 undies
#3 pair of undies from leaf pile. Still functional?

What did Team LBCC learn?

When a shovel of compost was added to the planting hole, the cotton portion of pair #1 (left above) was almost completely consumed by soil organisms. Three feet away, without compost, the #2 pair (right above) was more intact but suffered considerable decomposition, rendering it useless as a garment. Much to the LBCC team’s surprise, the third pair, #3, that was buried in leaves was indeed soiled BUT, after a good washing, possibly still functional.

Dr. Sangsupan reported, “The third pair was buried in the leaf litter of a deciduous tree beside White Oak Hall on the LBCC campus. I thought that given the number of worms and other soil critters I saw when I dug through the leaves that there would be a lot of microbial action to degrade the undies, but it didn’t work nearly as well as the ones we buried out on the farm.”


When we ponder soil health through the eyes of undie decomposition, three lessons apply:

Leaf piles full of creatures are fun to explore and super cool.


Soil plus compost REALLY ROCKS!!!

About the Author

Teresa Matteson

In 2001, I uprooted my family and moved to Corvallis to pursue a Master’s in Soil Science at OSU. Food waste composting research married with scholarly escapades into soil physics, chemistry and biology prepared me to be a member of the Benton SWCD Team. My passion is to revive regard for soil.

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