High Stakes in Soil Microbiology
New technology bridges data gap between soil physics and microbiology

Kenton Rod and Regan McDearis designed a new device—a porous soil stake—that, once installed, enables repeated sampling of a specific soil site at multiple depths, without further disrupting the soil.
(Photo by Andrea Starr | Pacific Northwest National Laboratory)
There’s a gap between soil physics data and soil microbiology data, so researchers Regan McDearis and Kenton Rod are building a bridge.
Well, it’s a soil stake, but it could be the technology that helps scientists glean even more information from soil at exact locations underground.
The soil physics field is full of deployable technologies that measure properties of soil continuously, providing valuable information about soil and water dynamics over time and space. The microbiology side, however, continues to struggle with repeated measurements because continual core sampling eventually turns a site into Swiss cheese, as McDearis describes it.
It's a big reason long-term soil sampling sites are scarce and invaluable to scientists. After repeated core sampling, the soil is riddled with core holes, disrupting soil hydrology and microbial communities, which obliterates any chance of consistent sampling in a given location.

To address this problem, McDearis and Rod designed a new device—a porous soil stake—that, once installed, enables repeated sampling of a specific soil site at multiple depths, without further disrupting the soil.
The 3-D printed stakes are sturdy housings for replaceable internal nylon mesh sample bags containing geomaterial (sand/silt/clay) which can be colonized by the soil microbial community. Printed with medical-grade, non-leeching resin, the stakes are covered in thousands of pore openings as small as 50 microns in diameter, which, when filled with water, act as a hydraulic bridge between the soil and internal sample bags. A key facet of the technology is that the smallest holes remain wet, even at very low soil moisture, helping maintain connection between the surrounding soil and the geomaterial in the sample bags. Researchers can easily collect the bags for microbial analyses and immediately replace them with fresh bags, sampling the same surrounding soil multiple times without digging new cores.

“We intend to pair these stakes with commercially available state-of-the-art soil sensors. It’ll give us parallel physical, chemical, and microbiological soil temporal data at consistent depths—something we haven’t been able to get until now,” said Rod.
The researchers worked closely with Pacific Northwest National Laboratory’s Instrument Development Laboratory—a group with vast engineering expertise that provides design and manufacturing consultation. Engineer Orlando Garayburu Caruso and technician Adam Ryan both contributed to development of the stake.
Looking ahead, Rod and McDearis hope for standardized monitoring across many field sites, giving researchers an index of communities. Such data has transformative potential in Earth system sciences, soil health, bioeconomy, and agriculture.
Published: October 31, 2024