When people picture ecosystems, they may have a scene straight from a nature documentary pop into their heads: the sun shines in a forest, grasses suck up light for photosynthesis, a mouse munches on this grass, an owl eats the mouse, the creatures respond to nonliving things like rain and temperatures, and energy flows through the system.
But what if we applied this concept to agriculture? Instead of just considering crops, soil, livestock, and other components of agriculture on their own, what if we looked at farms as ecosystems too—and used this understanding to improve production and limit impacts on the environment?
This is the research focus of Dr. Marilia Chiavegato, an assistant professor at The Ohio State University who studies agroecosystems management for food systems resilience. Dr. Chiavegato has a split appointment between the Department of Horticulture and Crop Science and the Department of Animal Sciences.
Her lab takes a unique “systems approach” to agricultural study, looking at plant, animal, and environmental interactions together and considering how these relationships change in response to disturbances, like flooding or extreme weather.
“I see an agricultural field as an ecosystem; I’m a systems thinker,” Dr. Chiavegato said. “I’m curious about how small changes can have big effects.”
Once researchers understand these complicated interactions, they hope to design better management strategies and propose changes that could balance sustainability with agricultural resilience and productivity.
“I think that the way to find this balance is to understand the entire complexity of these systems,” she said.
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Climate change is making extreme weather events more frequent, intense, and unpredictable, so agricultural producers may need to make changes to fortify their operations against these risks.
“We need systems that are able to deal with that uncertainty, that will survive and continue being productive,” Dr. Chiavegato said. “Now more than ever, it’s important to build this resilience.”
To decrease the negative impacts of these environmental disturbances, taking a broad range of agricultural factors into account will be key, she said. And while agriculture can play a role in exacerbating environmental problems, Dr. Chiavegato points to its ability to support solutions.
“I think agriculture has a role in the mitigation of climate change because of the potential of carbon sequestration and all of the management strategies that we can do to increase soil health,” she said. “I think we can manage agriculture in a way that is very sustainable and that contributes to the solution.”
Grasses and gases: understanding flooding impacts
Dr. Chiavegato spent much of her early career in Brazil, where she studied the effects of severe drought. After coming to Ohio and talking to farmers in the field, she realized many producers in the state face the opposite problem: flooding.
Flooding can be especially severe in fields planted with corn and soybeans. Excess pesticide- or fertilizer-laden water from these types of fields can run off, releasing nutrients like nitrogen into the state’s waterways and contributing to greenhouse gas emissions.
Converting traditional crop fields into perennial pastures or hayfields may limit these flooding risks and reduce the amount of greenhouse gases lost to the environment. For the past two years, Dr. Chiavegato’s lab has been working to collect baseline information on the effects of flooding on these types of grassy settings.
To develop this baseline, Dr. Chiavegato’s team considered three pasture plots in Northwest Ohio—one with no flooding, one with intermediate flooding, and one with severe flooding. She studied three similar plots in hayfields and historically grazed pastures in southern Ohio.
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Collecting roots gave Dr. Chiavegato’s team insight into plant development at each location. Scientists also analyzed the forage mass (the amount of plant material available for animal consumption), forage quality, and botanical composition (the combination of species growing) in each plot. Digging deeper, scientists gathered data on greenhouse gases found in the soil.
Dr. Chiavegato’s lab discovered the botanical composition changed significantly in the flooded plots compared to the dry ones. For example, less fescue—a common type of forage grass—grew, which made room for more clover plants to thrive.
The fescue that did grow was elongated—perhaps trying to grow above the flooded water, Dr. Chiavegato said. The plants were also made up of more stems than leaves, making them less ideal for grazing material or hay. Many had shorter roots, limiting how deep they could grow into the soil, and flooding made regrowth more difficult for the plants, which could cause declining productivity for producers over time.
“It changed not only the type of species that were growing, but how they grew,” Dr. Chiavegato said.
As the flooding didn’t visually look that intense—the plots only had a little water on top of the soil for two or three days at a time, four times a year—Dr. Chiavegato was surprised by the drastic changes in the plants.
“It’s very subtle,” she said. “What’s very interesting, from my perspective, is that the flooding is not that bad, so this is all happening slowly, changing the ecosystem over and over again.”
While there was less carbon stored in the soil of heavily flooded areas, the researchers didn’t see a considerable increase in nitrogen loss, so converting crop fields to these types of perennial pastures could prove to be an effective strategy to limit water quality and climate change issues.
Fruitful forage
Beyond flooding, researchers are exploring another complex problem: how to grow forage that’s productive year-round.
Many “cool season” grasses like fescue experience a growth slump in the summer as temperatures soar. Researchers hope to find ways to introduce plants that remain productive during this period, extending the grazing season.
One strategy could be increasing the diversity of plants grown for forage, including introducing more native “warm season” grasses. Besides being resilient to flooding (with their increased height and deeper roots), they grow well during months when cool season grasses aren’t as active, reducing the costs farmers may face when buying supplemental hay.
To understand how to plant these flood-resistant native grasses and incorporate them into Ohio agroecosystems, researchers are taking several approaches.
First, researchers are growing these grasses in greenhouses to fully understand their growth habits. They’re studying how long it takes for each species’ leaves to emerge, as well as recording their size and height. This research could help inform how farmers cut these grasses, ensuring high-quality forage. The scientists are also analyzing their roots and how they’re affected by fertilization.
It can be hard to introduce new plants in fields where cool season grasses already grow. To understand how to establish these native grasses, researchers set up small research plots in three fields—two traditional and one organic—to see what growing strategies work best.
Finally, researchers are bringing animals back into the equation.
“We thought that bringing back these native plants would increase resilience, but our animals are not adapted to them, so we need to understand how they’re going to react,” Dr. Chiavegato said.
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In southern Ohio, researchers cycle about 10 Black Angus cow-calf pairs into fenced-in research plots, allowing them to graze until they reach a certain target. Simply cutting the grass manually wouldn’t accurately simulate grazing conditions; bringing in real animals allows for more informative, accurate results.
Researchers hope that further understanding how warm season grasses interact with the various elements of the agricultural system will help inform how they plant forage and improve production.
Carbon crescendo
Capturing and storing carbon can be an effective way to reduce greenhouse gas emissions and limit the effects of climate change. But research shows that flooding can decrease the amount of carbon stored in soil, which can be problematic.
To prevent this, Dr. Chiavegato’s lab is exploring ways to add carbon back to the agricultural system. Scientists are analyzing what elements contribute the most to carbon fixation and sequestration, whether that’s roots, plants, animal manure, fertilizer, or some other component.
Research into this topic is just beginning, with Dr. Chiavegato having recruited 20 farm pairs (40 farms in total) to participate in an upcoming study comparing carbon in each location. The study will consider factors like whether the farm has pastures only or has fields with corn-soybean rotations, whether crops are perennial or annual, and what type of soil is present. Scientists will collect soil from different depths at each of these locations and analyze each sample’s carbon content using equipment in a lab.
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With three separate research focus areas and study locations across the Midwest, Dr. Chiavegato’s lab is staying busy. Scientists are still combing through data from the flooding and forage projects, and the carbon sequestration project could take up to five years, Dr. Chiavegato said.
“I don’t have all the answers yet,” she said. “It’s just a lot of huge datasets over a long time. And it’s difficult to manage a lab with six projects happening at the same time at different farms two hours away. Everyone is out in the field 12 hours a day sometimes, and then we have datasets with 12,000 observations to handle.”
But putting all the pieces of her research together and providing farmers with solutions that they can actually use is what makes it worth it, she said.
“What I most enjoy about my work is seeing the complexity right in front of my eyes,” Dr. Chiavegato said. “When I have all of this data, and I put it all together and see how the ecosystem is responding, it’s just beautiful.”
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Listen to Dr. Chiavegato explain her flooding work on KX’s podcast
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Follow Dr. Chiavegato on Twitter for updates about her lab
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Learn more about agroecosystems management
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Read more publications from Dr. Chiavegato
Her lab takes a unique “systems approach” to agricultural study, looking at plant, animal, and environmental interactions together and considering how these relationships change in response to disturbances, like flooding or extreme weather.