Like any organism, bioenergy crops interact with their ecosystem through a multitude of complex biological, chemical, and geological processes. Some of the most vital yet underexplored interactions, however, can be found just below our feet.

Stephanie Juice, a CABBI Postdoctoral Fellow at West Virginia University, is studying the interplay between crops, soils, and microbes — and what these interactions mean for soil carbon storage.

Juice found her love for ecology as an undergraduate at Cornell University, where she majored in Natural Resources and got her start working in the field.

“It was great being in the woods and studying soils and plant-fungus interactions,” Juice said. “I wanted to travel to different ecosystems and try to understand them, to see more of the world and more plant and animal communities.”

And travel she did. Juice has studied ecosystems across the world, from the streams and rivers of Venezuela to the Arctic tundra’s snow-packed soils.

“I love doing research, and I wanted to get to the point that I could be the person formulating the questions. So I entered into the Ph.D. program at the University of Vermont,” she said. “My dissertation was focused on how climate change affects ecosystem biogeochemistry and plant-microbe interactions.”

Excited to apply her skills further, Juice joined Edward Brzostek’s lab in the Department of Biology at West Virginia University in 2019. As a postdoc in CABBI’s Sustainability Theme, she studies interactions between bioenergy crops, microbes, and the soils they live in. She works on a computational model called FUN-BioCROP that simulates these soil dynamics, which can vary dramatically from place to place and crop to crop.

“Working on something that has such an important environmental and societal application is what attracted me to [the FUN-BioCROP model],” Juice said.

The FUN-BioCROP model is a version of the FUN-CORPSE model modified for use in bioenergy systems to simulate plant C allocation to N acquisition and microbial soil organic matter decomposition.

FUN-BioCROP (Fixation and Uptake of Nitrogen — Bioenergy, Carbon, Rhizosphere Organisms and Protection) takes an integrative approach to modeling carbon and nitrogen as they move through soil and crops.

When plants take in carbon during photosynthesis, that carbon plays a role in a variety of important biological processes. Some of the carbon is used in cellular respiration: Plants access energy just like we do, by converting glucose (a type of carbon) and oxygen into carbon dioxide and water. The carbon that isn’t used in respiration is allocated according to the plant’s needs. The growth of new plant tissue (new leaves, taller stems, larger roots) requires carbon, for example.

A lesser-known form of carbon allocation is happening just below the surface. Plants release carbon through their roots into the surrounding soil. Although this might appear wasteful at first glance, depositing carbon in the soil around their roots stimulates the growth and activity of soil microbes.

The microbes decompose organic matter in the soil, breaking it down into nutrients the plant can use. Among these important nutrients is nitrogen, which is necessary for plant growth.

Thus, plants and soil microbes share a mutually beneficial relationship. The plant provides carbon for the microbes, and the microbes provide nitrogen for the plant.

Juice and other CABBI researchers are using FUN-BioCROP to model the intricacies of these interactions between crops, microbes, and soil.

“This model is really exciting because it’s integrating new paradigms of how soil dynamics affect soil carbon cycling into predictive tools we can use to understand the implications of the decisions we’re making now in terms of energy sources,” Juice said. “This model can help farmers decide which (crops) to plant under different conditions to get the best soil carbon outcomes.”

Unlike previous crop models, FUN-BioCROP is the first of its kind to incorporate several key features of these crop systems: The model includes microbial activity, soil carbon protection, and rhizosphere processes, reflecting the most up-to-date science on how belowground processes shape coupled carbon and nitrogen cycles. The research team has also developed crop-specific parameters to characterize differences in soil-carbon dynamics between different crop species. In addition, FUN-BioCROP can mechanistically model tillage. Tillage is an important factor in making carbon more accessible to microbial decomposition, so its inclusion is a huge step forward for crop modeling.

These innovations in crop modeling will help inform farmers which feedstocks to plant, where to plant them, and how to manage their production to provide both energy and ecosystem carbon benefits.

It doesn’t stop there, however: Juice and her fellow researchers are still working on FUN-BioCROP, and they have plans to introduce additional features to make the model even more robust.

“We’re really interested in adding more microbial traits to (the model),” Juice said. “At the moment, it only includes one type of microbe. There’s currently no different microbial parameters, which could help us understand what would happen if, for example, there’s more bacteria, or there’s more fungi.”

“The other thing we’re excited to do is fine-tune the nitrogen dynamics of the model. There are different forms of nitrogen. They’re lost differently from soil, and plants and microbes can vary in their nitrogen preferences. If we can increase the level of detail in modeling the nitrogen cycle, we’ll be better able to project how the feedstocks affect nitrogen losses, which is hugely important to water quality and greenhouse gas emissions from soil.”

Overall, FUN-BioCROP represents a critical step in updating the belowground processes in bioenergy models and moves the community closer to designing a modeling platform that can optimize bioenergy crop management decisions to ensure the sustainability of bioenergy production.

Juice and the rest of the FUN-BioCROP team recently published a paper on the model in GCB Bioenergy: Bioproducts for a Sustainable Bioeconomy.

When she’s not working on FUN-BioCROP, Juice spends much of her free time enjoying the great outdoors. True to her love of ecology, she can often be found hiking or swimming with her kids and dogs.

— Article by CABBI Communications Specialist April Wendling