When visiting professor Trang Nguyen arrived at ³Õºº¾ãÀÖ²¿ last year to teach in the earth and oceanographic science department, she decided to create a Maine soil library for students to help reveal the hidden histories beneath their feet.
As a biogeochemist who studies the vast microbial community living underground, Nguyen saw the library as a hands-on way to show students what soil can reveal about the climate and ecosystems over time.
She expected to start from the ground up, collecting samples from across Maine. But before she could head out with a student assistant, her equipment, and a pair of boots, a check-in with a state agency changed her plans.
When Nguyen reached out to the USDA's Natural Resources Conservation Service (NRCS) in Maine to ask about a possible collaboration, she was told, “We have this soil collection that has been sitting in our closet for more than fifty years.” And they offered to share.
Not only does NRCS work with farmers and agrarian researchers, it likes to engage teachers and students, Nguyen learned. “They are excited that we have a soil teaching program here,” she said, partly because there is a declining number of soil scientists in the US. Meanwhile, the broad field of soil and microbial science offers many career opportunities, including cleaning up contaminated industrial sites, improving soil to support sustainable farming, and discovering new microbial processes that can lead to innovations in medicine, food (like Impossible Burgers!), and environmental technology, such as discovering ways to break down plastic.
When Nguyen drove to Dover-Foxcroft to see this closet filled with old dirt, sand, and rocks, she found many boxes of preserved soil samples, their colors still vibrant after decades. “Those samples were collected by many generations of people who have used them to build a soil map in Maine,” she said.
She and her assistant—Carleton College sophomore Madeline Kallin—converted the samples into monoliths, which are cross-sections of soil mounted in small wooden frames. Each frame is labeled with its place of origin and displays colorful stripes of soil that descend toward bedrock. “We are going back in time as we go down to the bottom of the series,” Nguyen explained.
“All the very interesting questions about life, about climate, and about our future lead down to the ground.â€
—Trang Nguyen, visiting assistant professor of earth and oceanographic science
The collection reveals the glacial history of Maine, as well as clues to the vegetation living on top of the land. Some layers are dark and organic, recently formed from decomposed plants. Others show older development, with shifts in color marking the slow leaching of minerals and nutrients down to the depths.
Taken together, the collection provides a record of the state’s natural history and a tool for students to see soil as a living system, a climate change regulator, and a source of scientific discovery.
Students in Nguyen’s fall course Soils and Terrestrial Carbon Cycling are exploring how much soil helps to regulate the climate. “Eventually, they come to understand that the amount of carbon stored in the soil is way larger than all the carbon stored in plants, animals, and the atmosphere all combined,” Nguyen said.
This is because the billions of microbes that live in just a teaspoon of soil play the key roles of controlling the bottleneck of carbon sequestration via their ability to break down organic materials. Some microbes, working alongside plants, also help suck carbon from the atmosphere through photosynthesis. At the same time, however, soil microorganisms are contributing to climate change by releasing carbon dioxide as they feast on dead plants and animals, helping to decompose them.
Louisa Linkas ’26, an earth and oceanographic science and computer science major, said she enrolled in the class because she wanted to learn more about “the pertinence of soil cycling and soil health to our global climate systems and agricultural practices,” and that she's enjoying the course’s hands-on approach.
EOS major and history minor Will Riley ’27 said he, too, wanted to learn more about the role of soil in the carbon cycle, and that he also liked the course's exploratory nature. “I was also drawn to the class because of the many hands-on opportunities there are in Maine to explore soils, especially with the resources and land available at the Schiller Coastal Studies Center,” he said, one of the sites where the class has sampled soils.
Nguyen said she was first drawn to the study of soil as a college student herself, when she realized that “all the very interesting questions about life, about climate, and about our future lead down to the ground.”
“Soil is the foundation of our food system and the key to solving the climate puzzle. I am committed to soil, and I find a lot of joy studying it.”
