A few years back a campaign was started (in California, I think) called the Soil Your Undies Challenge. It encouraged farmers to bury a new pair of cotton underwear in a field for two months, then dig them up to see what the microbes in the soil had done to the cotton.

The condition of the undies was an easy indicator of the health of the soil.

In some cases, the underwear was hardly damaged at all. A good washing, and they would be wearable. This indicated a dry, unhealthy soil.

Some underwear had nothing left but the elastic waistband and the seams that had been sewn with non-cotton thread. All the cotton had been eaten away, which indicated healthy soil.

Between those two extremes were various degrees of deterioration. Some undies were a little holey and ragged, while others looked like something a zombie would wear.

To appreciate this challenge, it’s important to know that plants only get two things from above ground: carbon dioxide and light. Everything else comes from below. Healthy plants need healthy soil, and healthy soil is rich in tiny organisms such as bacteria and microbes, plus water.

There is a communication system (still little understood) between the leaves above and the roots below. The roots don’t guess what the upper parts of the plant need, they are told what specific ions are required, and the roots make an effort to attract tiny critters that will eat certain bacteria in the soil and poop out those ions, which will be absorbed and sent upward.

(If you are a soil scientist, please forgive me if my explanations are over-simplistic and perhaps a little askew.)

An example of how quickly the upper plant can communicate with the roots is given by Dr. Elaine Ingham, a soil biology researcher. She took some graduate students to a cave in Oregon. On a mountain above the cave was a stand of large, virgin Douglas fir trees, and the roots of some of the trees were dangling down inside the cave well below ground level.

Leaving one student in the cave with a cell phone, she took the others up on the mountain, and they injected blue dye into the trunks of some of the trees, noting the exact time they did so.

The person in the cave was to observe the roots and call when blue dye appeared there. It took three minutes.

The bottom line is, plants need soil with plenty of bacteria, microbes, enzymes, worms, moisture, and such. And the Undies Challenge is a simple, yet effective way to test the richness of soil. All it takes is cotton undies, a shovel, and two months of waiting.

Winter, of course, is not an opportune time to try the Undies Challenge. Wait for spring.

There is an excellent article about a class of kindergartners who did an Undies Challenge experiment. Go to gatewaygreening.org, then search their site for Undies. The article is by Rachel Wilson.

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