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Emily Gao ’24 teamed up with ITC and the registrar on the course election system.
Most carbon in soil is eaten by microbes and respired back into the atmosphere as carbon dioxide, contributing to global warming. As part of her culminating experience project, Molly Stevens ’25 has spent her senior year working with Professor of Earth Sciences Carl Renshaw and Senior Research Scientist Josh Landis on a possible solution.
By adding a mixture of iron and silica, aka iron slag, to the soil, Stevens hopes to trap carbon in a form that’s resistant to degradation by the microbes, keeping it in the ground. In a project funded by the Climate Futures Initiative, Stevens, Renshaw, and Landis on March 11 added the slag to two experimental plots at the Organic Farm.
If the test is successful, farmers could be incentivized to add iron slag—currently an industrial waste product—to their fields to improve their yields while also possibly earning carbon capture credits.
Director of Photography Katie Lenhart joined the trio to document how they were using campus as a lab to help combat climate change.
Photos
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Professor of Earth Sciences Carl Renshaw heads down to the Dartmouth Organic Farm fields on March 11, where a plot was saved for the carbon capture study. (Photo by Katie Lenhart)
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Molly Stevens ’25 ties a measuring tape in place on a test plot. (Photo by Katie Lenhart)
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The test plot was split into three sections, each with four 4-foot-by-5-foot rectangles. Soil from the first plot will be tested regularly for carbon levels, the middle will be the control where no slag was added, and the third section will be tested annually. All tests will be compared to soil Molly collected last fall, which is considered the “initial condition.” (Photo by Katie Lenhart)
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Molly Stevens ’25 pours pre-weighed and bagged slag, an iron silica mixture, into a power spreader before putting it atop part of the snow-covered plot. (Photo by Katie Lenhart)
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The first attempt at applying the slag with a power spreader yielded uneven distribution. (Photo by Katie Lenhart)
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With the power spreader not working, it was back to hand throwing. Senior Research Scientist Josh Landis, who spent time as a baker, had the perfect technique. (Photo by Katie Lenhart)
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The completed first third, which will be sampled most frequently for carbon levels. (Photo by Katie Lenhart)
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As the snow melts the slag will seep into the soil, beginning what researchers hope will be a mutually beneficial process resulting in both carbon capture and increased soil fertility. (Photo by Katie Lenhart)
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Josh Landis and Molly Stevens ’25 start spreading the slag over the third section, which will be tested annually, leaving a control section in the middle. (Photo by Katie Lenhart)
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Similar experiments have been taking place at Carleton College in Minnesota, but bringing the project to Dartmouth gives students hands-on access to the soil for better testing and understanding the chemical makeup. (Photo by Katie Lenhart)
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Josh Landis, Earth sciences professor Carl Renshaw, and Molly Stevens ’25 head back to the lab after a good morning of work. (Photo by Katie Lenhart)
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If iron slag application becomes a viable carbon capture option, farmers could be paid to utilize the mixture on their fields. Not only would they see potential improvements in soil fertility, but they could receive carbon credits—making this one of the few current carbon capture proposals with a clear economic model, Renshaw says. (Photo by Katie Lenhart)
