Backyard Science: Biologically Active Soil


Previous studies have shown the biological activity of soils can be determined in a quirky manner with cotton briefs.

This backyard experiment in Oregon, Ohio, involved the potential breakdown of cotton fiber to make gross observations about biological soil activity.  The study started May 22, 2017 and continued undisturbed until October 7, 2017, for a total 137 days.

Materials and Methods

Three pair of new men’s 100% cotton briefs were washed with a small unmeasured amount of detergent without additives and city water to remove any manufacturing residue.  They were rinsed twice and dried.  Each pair was cut in half through the waist elastic to the crotch.

Each half was weighed.  Left halves of each pair were numbered 1, 3, 5, and right halves of each pair were numbered 2, 4, 6.  The #1 half, an untreated control, was kept inside the house at ambient room temperature.

Each of the remaining five halves was buried in a different location of the property.  The sites were recorded.  The elastic waistband portion of each underwear half was allowed to remain slightly above the soil level for visual location.  The five treated  halves remained undisturbed in soils of native silty clay (halves #3, #4, #5), previously purchased and amended sandy loam in a vegetable garden (half #2), or amended sandy loam in a hosta bed (half #6).


Brief halves 1, 3, and 5 each weighed 33 g; brief halves 2, 4, 6 each weighed 35 g before burial.  Even-numbered halves were heavier as they included the extra fabric from the briefs’ slit construction.

Day 137, with shovel in hand,  the study was concluded.  Three of the five men’s underwear halves were not found even though the elastic had been at ground level and the location had been recorded.

after picture buried vs control

The two recovered items, half #2 and half #5, indicated pretty complete breakdown of cotton as shown in the photos.  Insufficient cotton remained for final weight determination.  Breakdown of the cotton was likely a result of pretty good biological soil activity.  Except for a few cotton remnants, only the elastic waist and seam portions remained.


Over 4 months for this study was too long but scientific curiosity of two retirees was satisfied.  Stopping the experiment at 2 months in order to compare this study with the previous study went out the window in the heat, humidity, and mosquito-ridden environment.  This was a fun backyard experiment and shows our soil is indeed biologically active, whether native clay soil or purchased and amended sandy loam soil.