Beneath the Surface

Bronte Sone’s research subjects aren’t easy to work with — they’re microscopic and number in the billions in just small samples. Yet, they are vital to agricultural systems.

Soil microbial communities, which include bacteria, fungi and archaea, play a critical role in ecosystems. Soil microbes help with nutrient cycling, produce and consume greenhouse gases, enhance plant growth, and help plants access more water and nutrients, among other benefits.

Sone’s passion for her research is fueled by the belief that understanding soil microbes is essential for sustainable agriculture and environmental resilience.

“I just find it fascinating, that you have these tiny organisms, but they are so important to ecosystem function,” she said. “I think soil microbes are really key to us being able to continue to grow crops even given a lot of environmental stressors and they could potentially, in combination with conventional fertilizers, play a role in our ability to increase production even further, which we are going to need.”

Sone will graduate with a doctorate in soil and land resources from the University of Idaho in December 2024 and continue her career studying soil microbial communities.

Discovering Soil Science

Sone first became interested in soil science as a freshman at St. Lawrence University in Canton, New York where she was studying psychology. Originally from Windham, Maine, Sone missed being outside, so she enrolled in St. Lawrence’s sustainability semester where she lived in a farmhouse off campus helping with a sheep farm and sugar maple operation.

“That was the experience that solidified for me that I wanted to pursue agriculture,” she said.

Sone transferred to the University of Maine and completed a bachelor’s degree in sustainable agriculture. After graduation she started working on different farms across the United States and Canada, gaining experience managing a farm with the goal of one day starting her own.

After two years, she realized that each farm had different ways of managing their soil and there was a general lack of knowledge of what the different practices were, and which were most effective.

“That’s what made me interested in grad school because I wanted to try and find some of those answers,” Sone said.

She began looking for soil science graduate programs and discovered U of I and Assistant Professor Michael Strickland.

“He had a lot of different projects going on — there were ag projects but there were also some forestry projects,” she said. “His background is in ecology, so I liked that he had a well-rounded perspective and research program. His research also tied in with climate change and real-world problems and that really resonated with me.”

Cover Crop Diversity

Sone decided to jump immediately into the doctorate program at U of I once she realized the careers she was interested in all required a doctoral degree. Her research focused on the impacts of cover crop species and diversity on soil microbial communities, with the goal of better understanding how agricultural management practices influence soil health.

Through her research, Sone found that increasing cover crop diversity doesn’t necessarily increase microbial diversity, but the specific composition of cover crop species can have dramatic effects. She planted several test plots on the Palouse, including a high diversity mix of six crop species, and several plots of one to four crop species.

“We found that cover crop composition or species identity was more important than diversity,” Sone said. “Our high diversity mix performed worse than a lot of our other treatments, even the individual species, and it performed kind of on par with our fallow controls where we didn’t plant anything.”

An oilseed and legume mixture performed the best, leading to increased yield for a winter wheat crop. Sone acknowledges that more research is needed to identify the best cover crop rotation for farmers.

“We need more system specific research to really determine what cover crops are best,” she said. “I still think there is a lot of promise for cover crops to improve soil health and the potential to improve crop yield, but it’s not one-size-fits-all.”

Future Research

Sone has accepted a postdoctoral researcher position with Jessica Miesel, an associate professor of fire ecology at U of I, where she will study how fire intensity and duration impact soil microbes and soil nutrient cycles. Her long-term aspiration is to remain in research, potentially at a national lab or working for the Agricultural Research Service or the Forest Service, studying the function of soil microbial communities.

“That’s where I want my work to take me is to combine microbial community data, so looking at who is present, and then using these other metagenomic techniques to get at their function and trying to link that,” she said. “We know that climate change and changes in the environment can impact who’s present in the soil, but we still don’t have a clear picture of how that changes their function. Is it going to increase the amount of nitrogen that’s available to plants or is it going to decrease the amount? I want to get at that.”