BGSU researcher finds Lake Erie dredged material correlated to better crop yields

Research from Angelica Vazquez-Ortega, Ph.D., discovered root systems, yields and above-ground biomass all improved when grown with sediment from Lake Erie

Research from a Bowling Green State University scientist found what could be a game-changing solution for agricultural practices in the Lake Erie watershed. 

As part of the statewide effort to protect Lake Erie from harmful algal blooms, the Ohio Legislature in 2020 enacted a law that prevents open-water disposal of dredge from the Toledo Harbor, from which the U.S. Army Corps of Engineers annually removes roughly 1.5 million cubic yards of material to maintain water levels for the shipping channel. 

To the naked eye, the dredge looks unremarkable — but Angelica Vazquez-Ortega, Ph.D., an associate professor in the BGSU School of Earth, Environment and Society, found the material pulled from Lake Erie appears to have a positive effect on the growth of crops. 

"Every time I show the photos to any stakeholder, they're fascinated by it: the higher the dredge content, the more robust the root system." - BGSU Associate Professor Angelica Vazquez-Ortega, Ph.D.

Vazquez-Ortega’s research discovered that using dredged material from Lake Erie in place of fertilizer appears to be correlated to higher crop growth and yields, offering a potential winning solution for all stakeholders.

Photos from the research have been eyebrow-raising for farmers, scientists and policymakers alike: The research documented consistent improvements in root development, plant biomass and crop yields when dredged sediment is incorporated into soil.

"Every time I show the photos to any stakeholder, they're fascinated by it: the higher the dredge content, the more robust the root system," Vazquez-Ortega said. "It's also correlated to higher biomass in the root system, higher biomass above the soil and a higher yield."

Corn root systems were more robust when grown with dredged sediment from Lake Erie. From left, roots of corn are shown with 0%, 5%, 10%, 20% and 100% dredged material. (Contributed photos)

Vazquez-Ortega’s research team devised greenhouse experiments to study the effects of dredged material on multiple crop varieties, including staples like corn and soybeans. They prepared several mixtures – one that was 100% farm soil, one that was 100% dredge and some in between – and found that the more dredge they used, the better the results.

The research team also tested the dredged material on various specialty crops like carrots, tomatoes and lettuce. 

In greenhouse settings, the success was consistent.

"It was the same story," she said. "We've been consistently showing the same trends."

In greenhouse settings, even speciality crops like carrots performed better with dredge. Carrots above are shown with 0%, 10%, and 100% dredge. (Contributed photos)

The next step was to replicate the success on an actual farm. In a field experiment conducted approximately 20 miles south of Bowling Green, researchers tested dredged material's effectiveness, accounting for real-world variables like soil compaction from heavy farm equipment traffic.

Vazquez-Ortega observed that corn grown under normal conditions using typical soil with traffic from farm machinery had very low yield.

Corn fields planted with dredged material, however, performed better and had more robust root structures in all conditions.

"The two fields with dredge had better yield, even with traffic from heavy farm equipment," she said. 

The successful early results are an encouraging possible solution that could limit the use of synthetic fertilizers, which contributed to nutrient runoff that fueled the 2014 Toledo Water Crisis.

As part of the project, Vazquez-Ortega's team is monitoring both surface and subsurface runoff from fields treated with dredged material to understand how many nutrients are leaving the fields. 

If dredge proves to be a capable long-term amendment to farm soil, it could help close a loop by limiting runoff and using less fertilizer, typically a major expense for farmers that can be washed away by rainfall.

"If we can prove the export of nutrients is the same, we'll know nutrients from dredge are retained in soil or being accumulated by plants," she said. "On the contrary, we already know synthetic fertilizer can leave the system very quickly."

Vazquez-Ortega believes the experiment’s success is linked to the chemical composition of the dredge, which is consistently high in calcium. 

Researchers will continue to study the effects of using dredged material in farming, but there has been no doubt that the early results have been encouraging for all parties involved.

"It appears the addition of dredge can mitigate some farm traffic and the roots can still grow, be healthy and have stronger yields,” she said. “It’s been super cool to learn that."