What does sustainable agriculture look like? A Fordham graduate student’s project points to one answer: side-by-side planting of crops that each enrich the soil, leaving it more fertile than before.
That’s how planting is done in a number of countries around the world including Ethiopia, the focus of graduate student Tierney Kulju’s project. Kulju is studying practices that “have been in use for thousands of years by Indigenous communities, by traditional farmers,” to help foster more sustainable approaches for smallholder farmers and in large-scale agriculture, she said.
As a Fordham graduate student in biology, Kulju is involved in a transatlantic research effort —involving the New York Botanical Garden, Ethiopian scientists, and other institutions—to address interconnected challenges including sustainable growth as well as helping crops withstand the droughts that are more common because of climate change.
New York Botanical Garden Partnership
Kulju got involved because of Fordham’s ties with the botanical garden, which is across the street from the Rose Hill campus. While interning there as an undergraduate, she discovered her interest in intercropping, or planting different crops together. It’s been done for centuries, often by mixing a grain crop that depletes the soil, like wheat, with a legume crop that replenishes the soil with nitrogen or other nutrients.
In collaboration with scientists at Wollo University in Ethiopia, Kulju, FCRH ’24, is helping to show what happens in the soil when two legume crops are planted together. Working at Fordham’s Rose Hill campus and its Louis Calder Center, a biological field station, she’s replicating Ethiopian intercropping in New York soils, hoping to gain insight that helps revitalize the practice in Ethiopia and elsewhere.
“Basically, we know almost nothing about legume-legume mixtures,” said Alex McAlvay, Ph.D., a scientist at the botanical garden who mentored Kulju’s undergraduate research and is sitting on the committee for her thesis, focused on her intercropping research.
Sustainable Farming with Fava Beans and Peas
Last summer she planted fava beans and field peas in diverse soils at the Calder Center, and today she’s conducting experiments to find out how much nitrogen and carbon they left behind.
Fava beans and field peas, long grown together in Ethiopia, are one of many mixtures that “have often been ignored or dismissed as backwards or primitive,” McAlvay said. “They’re based on millennia of observations and experimentation, so they’re grounded in time-tested traditions.”
The two plants have different root structures that allow them to occupy the same soil at the same time, Kulju said. They each have a way of sheltering and nourishing underground microbes that, in turn, convert nitrogen in the air into a form that’s usable by plants.
Because they leave behind nitrogen in the soil, legume intercropping can be alternated with nitrogen-hungry plants such as wheat and corn to replenish the soil, reducing the need for heavy doses of artificial fertilizers that wind up running off the land and polluting the water supply, Kulju said.
The healthier soils fostered by intercropping are also better at retaining water and withstanding droughts, she noted.
A Hungrier World
There’s high demand for soil-depleting crops like wheat and corn, she noted—“People love them, people want them, and the world is getting larger and people are going to want more,” she said. “So we’ve got to find ways to address that in a way that’s sustainable for both people and for the environment.”
She hopes her research can help point the way to wider use of dual legume mixtures as a sustainable, environmentally friendly approach that could also be more profitable—in part because of the savings on fertilizer, she said.
Through her research collaborations, she said, “I’ve just been very inspired to make a difference that is feasible, scalable, but also something that’s sustainable for the long term.”
Learn more about the Traditional Grain Mixtures Project, led by the New York Botanical Garden.
