Soil Your Undies Lesson: By Rachel Wilson

There is a lot happening in the soil of your garden that you can’t see without using a microscope!  Did you know there are more soil microorganisms in a teaspoon of healthy soil than there are people on earth?  The Soil Your Undies Challenge was recently popularized by American farmers to help promote the importance of healthy soil, but it’s also a great activity to use with children in the school garden or in the backyard.  Bury a pair of cotton underwear in your soil for two months to learn how healthy your soil is!

We followed GGI Educator Tonia when she co-taught this experiment with Mrs. Flanders’ kindergarten class at Mallinckrodt.  Mrs. Flanders found the experiment in the Missouri Department of Conservation’s Xplor magazine and thought it would be a great way to connect to the school garden. 


The class chose two spots in their school garden – one in a raised bed and one in the grass lawn – for their test sites.   Then, they shoveled into the soil 6” under the surface and buried a pair of 100% cotton underwear in both holes.

Mrs. Flanders asked her students to make predictions on what they think each underwear will look like in two months.    The majority of the students believed that both sites would have healthy soil.


            After waiting two months, the class recalled their predictions and dug up each pair of undies.  The underwear in site #1 in the garden bed was dirty and severely shredded leaving almost just the elastic waistband.  This meant that their soil has a healthy soil food web with lots of hungry critters! 

When they dug up the underwear at the site #2 in the grassy lawn, they found the pair was more intact and less of the cotton had been eaten.  The students learned that the soil in this spot is losing its nutrients and the critters need their help.  They brainstormed ways to revitalize the soil like mulching and loosening up the soil and adding more plants.

Tonia advises that this experiment worked well using a garden bed that was full of growing plants because the live roots attract microbe activity – and eat your undies!  Having a second site helped students to compare and brainstorm what needs to be changed in an area without healthy soil. 

Mrs. Flanders says, “It’s a hilarious and fun way to get students discussing healthy soil and decomposers!”

More soil health facts: