New research from the Harmful Algal Bloom Research Initiative is helping farms become part of the solution to mitigate algal blooms on Lake Erie by putting excess sediment to use.
Each year, the state of Ohio dredges approximately 1.5 million tons of sediments from its Lake Erie ports to keep federal navigation channels clear for ships. This dredged material is made up of loose sand, clay, silt, and gravel from the bottom of water bodies.
Researchers developed a demonstration farm to test soil health, agronomic productivity, and the potential environmental effects of applying dredged sediment to farm fields.
The majority of dredging on the lake occurs at the Port of Toledo, which has particularly high sedimentation. In past decades, harbors would dispose of their dredged material by dumping it in the open lake. In 2020, however, Ohio banned open water disposal of dredged sediments in an effort to improve water quality and reduce annual algal blooms. Currently, dredged sediments from Toledo Harbor are stored in a confined facility — with a limited capacity of 10 years — and the state is looking for beneficial uses for this material.
In response to this need, a team of researchers led by Dr. Angelica Vazquez-Ortega of Bowling Green State University and funded by HABRI investigated the viability of using dredged material as an agricultural farm soil amendment. Researchers reasoned that applying sediment to farm fields would return nutrients that were exported from the Maumee River watershed into Lake Erie.
They also proposed that such soil amendments could help replace eroded topsoil, benefit crop yields, reduce phosphorus export, and potentially reduce harmful algal bloom severity. Further, proving that dredged materials are beneficial for soil health and crop yields might motivate farmers to adopt this resource and practice.
“Using dredged material from the Toledo Harbor as a soil amendment represents a new potential agricultural best management practice for improving soil health, by completing the soil cycle and returning eroded sediments back to watershed fields,” Vazquez-Ortega said.
Through the project, the team developed a demonstration farm to test soil health, agronomic productivity, and the potential environmental effects of this beneficial use. On the farm, one area received dredged materials while another did not, serving as a control.
During the experiment, researchers also took into consideration compaction exerted by heavy machinery used to spread the dredged material. To track success, researchers also installed a system to monitor the export of nutrients in both surface and subsurface runoff from field edges.
Results showed that amending farm soil with dredged materials improved the soil’s chemical health — such as an increase in soil organic matter and available phosphate to help plants grow. In comparing areas with and without compaction, researchers found no difference in soybean yield but lower corn yield in fields that had no dredged material applied. However, in fields with soil amendment, yields were the same regardless of compaction.
“This research found that soil health and crop yields improved when the sediments were used in the demonstration farm,” Vazquez-Ortega said. “The addition of dredged material outbalanced the detrimental effects of soil compaction by the use of heavy machinery used to broadcast it.”
From this, researchers concluded that adding dredged material doesn’t affect the yield of cash crops negatively. Notably, the study found no preferential accumulation of heavy metals in corn crops applied with dredged sediment when compared to 100% farm soil. Analysis of data from the edge-of-field monitoring system is still ongoing, with more results to come.
“We managed to obtain additional funds to hire a graduate student to analyze the nutrient export from the fields, and we are working on a report that will include soil health, crop yields, and nutrient export from the field,” Vazquez-Ortega said. “More great information will be made available soon.”
Learn about this and other harmful algal bloom research projects in the newly-released 2025 HABRI Report, viewable on Ohio Sea Grant’s website.
Ohio Sea Grant is supported by The Ohio State University College of Food, Agricultural, and Environmental Sciences (CFAES) School of Environment and Natural Resources, Ohio State University Extension, and NOAA Sea Grant, a network of 34 Sea Grant programs nation-wide dedicated to the protection and sustainable use of marine and Great Lakes resources. Stone Laboratory is Ohio State’s island campus on Lake Erie and is the research, education, and outreach facility of Ohio Sea Grant and part of CFAES School of Environment and Natural Resources.