Digging In

When she’s asked to define soil, geology professor Anna Lindquist gives two answers.  

“The technical definition is it’s a mixture of mineral matter and organic matter and pore space,” says Lindquist. “That pore space is then filled with some mixture of water and air that changes from day to day and from season to season, depending on the local conditions.” 

Her second definition is nearly poetic: “A cloak of loose, soft material held to the Earth’s hard surface by gravity is all that lies between life and lifelessness.” Lindquist says she loves this description—from soil scientist and writer Wallace H. Fuller’s 1975 book Soils of the Desert Southwest—and she’s shared it with her students in this spring’s “Soil: Science and Sustainability” course. 

“A lot of environmental studies classes are higher level,” says Kingsley Hollon-Coleman ’24 (Safety Harbor, Fla.). “I wanted to take an environmental studies class, but I’m a freshman. This course looked really interesting and it didn’t have any prerequisites.”

The popular course, cross listed in environmental studies and geology, bridges the gap between learning the scientific basis of soil formation and basic soil properties to a more human component of how soil affects people, from agriculture to climate change, says Lindquist. 

One of the course requirements is that students get their hands dirty. Even in the pandemic, there are still opportunities for students to do so. Lindquist left Ziploc baggies of soil outside her office for local students to pick up. The Geology Department also mailed baggies of soil to students studying remotely, while other students chose to dig soil out of their own yards at home. 

“We had assignments working through the soil, looking at its structures and physical properties,” says Julia Chamberland ’23 (Grinell, Iowa), an environmental studies major.  “One of the soil types I tested was really high in clay content. When I was done, I mixed it together with water and made a little clay dinosaur out of it! I really enjoyed that assignment.” 

In late February, during a section on soil and agriculture, the class did a virtual field trip with a Wisconsin farmer who discussed his farming operations. Ordinarily, the field trip would have been in person, with students standing right on the farm’s rich and varied soil, but Lindquist made it work. “One of my colleagues went out to his farm last semester during peak harvest season and did a video walk-through of the farm to share with the class,” she says. 

At least two students in this spring’s class both worked on farms before taking this course.  Chamberland interned at Middle Way Farm in Iowa last summer. Brennan Persenaire Hogeterp ’23 (Grand Rapids, Mich.), an international studies major with a concentration in food, agriculture, and society, says he had his first real job on a farm when he was 15. He’s considering more farming in the future. 

Hogeterp is especially excited by a recent course section on cover crops which can help solve problems like erosion and nitrogen leaching. “They are a natural solution that you can specialize to your own farm,” he says. “If your soil is quite poor, for example, you can plant legumes to fill up the nitrogen.” 

For Lindquist, one of the unexpected bonuses of this spring’s class has been the soil itself. 

“With some students in other places, we’re seeing a greater diversity of soils popping up in this class than I usually get when we’re running the class at Macalester,” she says. “There is a whole ecosystem in soil that people don’t appreciate because they tend to think it’s just ‘dirt.’ Part of what I hope students will get from this class is an appreciation that soil matters. Even if it’s not something that they will go into, soil is influencing their life.”