Uncovering the microbial activity happening in your soil.
You might not think a pair of cotton underwear has much to tell you about your farm. But bury a pair in the soil, leave it there for 45 days and dig it back up, and you may see a surprisingly good visual representation of what’s happening in your land. That was the idea behind CFE’s “Soil Your Undies” experiment, led by CFE Conservation Agronomist Ashilyn Klaassen. Inspired by a project she worked on during an internship with the Natural Resources Conservation Service, this gave our agronomists an opportunity to compare soils under a variety of management practices while helping farmers take a closer look at the living organisms working beneath their feet.
Cotton is a natural material that soil organisms can break down. By burying a pair of cotton underwear and evaluating how much fabric remains after a set period of time, farmers can get a simple, visual indication of how actively organisms are breaking down organic matter. Over the course of two growing seasons, Ashilyn put 22 fields to the test, with a variety of crop rotations, tillage practices, manure applications and additional conservation practices.
Inside the Microbiome
CFE is all about building strong communities—the ones we live and work in, and the ones in our soil. Just as we live in communities where everyone has a role to play, our soil is home to a community of microorganisms, each with its own job to do. Billions of microbes, bacteria, protozoa, fungi and nematodes make up the soil microbiome that is responsible for nourishing our crops. The level of activity in these microbial communities has proven to be a significant driver of soil health and, as a result, plant growth and yield.
The same microbial action that eats away at cotton in the underwear is also breaking down other organic matter in the soil, turning it into crop-available nutrients. “You can really do this with any type of natural material or clothing article,” Ashilyn says. “Underwear is just a good representation because it has that thick elastic band that is essentially plastic and isn’t going to be eaten away.” The elastic waistband gives farmers a helpful reference point. The more the cotton portion has broken down, the more obvious the difference can be when the underwear is dug up. By seeing how much of the underwear has disintegrated, farmers can have a glimpse into how management decisions can influence the environment those organisms live in.
The Dirty Details
CFE wanted to get a broad scope of fields to better display the impact that conservation practices can have on the activity going on in the community beneath the soil. We did this by choosing fields with a wide range of management histories and conservation practices. Our selected fields represented a broad range of conditions, including pasture transitioning to corn, three-plus-year crop rotations, long- and short-term no-till, corn-on-corn, conventional tillage, strip-till, cover crops, manure applications and fields without a history of conservation practices. The goal wasn’t to crown one practice as the winner, but instead, to provide another way to start a conversation about what is happening below the soil surface.
For CFE’s experiment, the underwear was buried approximately four to six inches deep—deep enough to be in the soil where microbial activity is taking place, but not so deep that activity begins to decline. “You want to make sure it’s in that sweet spot where it’s not on the surface, but it’s low enough that it’s right in the root zone where those microbes are active,” Ashilyn explains.
After 45 days, the underwear was dug up, and the evidence of microbes was evaluated. That 45-day timeframe came from Ashilyn’s previous experience with the experiment. At 30 days, she found there wasn’t enough decomposition to make differences easy to see. At 60 days, too much of the material had broken down, making it harder to distinguish differences between fields.
The Results
The results from the 2025 experiment showed clearer differences than those from 2026. The underwear buried during the 2025 growing season showed noticeable levels of decomposition that corresponded with the degree of conservation practices used in the fields. The most eaten-away underwear was the pair buried in field eight that was actively planted as CPR. Close behind it was field three, which has been no-till for many years, and field 11 that had cover crops planted after corn. The results observed from the underwear that was buried during the 2026 season were there, but less noticeable than the previous year. Ashilyn believes weather played a significant role. This year, the underwear was buried from June 15 to July 30, a relatively dry stretch across much of the CFE territory. “Microbes like moisture,” Ashilyn says. “It’s easier for them to move and break things down when they’re in a moist environment. It doesn’t need to be wet, but they need some moisture.”
Temperature also plays a role. Soil organisms are living things, and they function best within a range of conditions. The microbes don’t want to be too hot, as that starts to slow them down and can kill them off. On the flip side, if they’re too cold, they’re not going to move because they don’t have enough energy to keep producing and functioning.
Ashilyn compares it to people. “When you talk about microbes in the soil, they’re living things, so you can basically think about how you would treat a human and apply that to microbes,” she describes. “You don’t want it too wet, and you don’t want it too dry. You need that Goldilocks zone right in the middle.” While the results from the 2025 experiment were more defined than those from this summer’s experiment, it does not mean the microbes were not active. They simply were not provided with the ideal conditions by Mother Nature.
Building the Community
Farmers can’t control rainfall or temperature, but they can still have an influence on the environment where soil organisms live. One of the most significant factors is soil disturbance. Ashilyn compares intensive tillage to a tornado moving through a community. “If you had a tornado come through your town with no warning, people would die, people would be injured, and it would take a long time for that community to recover and rebuild,” she says. “If you come through and rip up all of that soil and break apart those communities, you’re disrupting them. It takes a long time for those communities to build back up.”
That doesn’t mean every acre can or should immediately transition to no-till. Different soils, rotations and farming systems require different approaches. But reducing unnecessary disturbance where it makes sense can help create a more stable environment for soil biology. Other management practices can help build the resources those organisms need, too. Manure, for example, adds both organic matter and microorganisms to the soil. “Adding manure is one of the fastest ways to kick-start your microbes in the soil,” Ashilyn shares. “You’re adding bacteria and organic matter that’s already in the manure, giving the microbial community a kick-start.”
Cover crops can also contribute additional living roots and organic material to the system, providing another source of food for the organisms living in the soil. For farmers who have been using conservation practices for years, the benefits of that long-term investment may already be visible. For others, the underwear experiment is simply another reason to start asking questions about what is happening beneath the surface.
The “Soil Your Undies” experiment isn’t a substitute for comprehensive soil testing or scientific measurements of soil biology, but it does make something that is normally invisible a little easier to see. Whether you’re evaluating tillage, adding cover crops, incorporating manure or simply trying to better understand the soil beneath your farm, CFE is here to help. Sometimes, getting a better look at your soil starts with something as simple as digging up a pair of underwear.
