Agricultural Use of Dredged Materials

Research into how agriculture intersects with the health of Lake Erie is continuing with projects funded by the Ohio Lake Erie Commission through the Lake Erie Protection Fund. The recently formed DRIFT committee (Dredge Research and Innovation in Farming Team), composed of farmers, soil experts, and staff of Soil and Water Conservation Districts and the Natural Resources Conservation Service, reviewed grant applications and recommended approval of two grants that they hope will generate valuable information about the potential beneficial reuse of dredged materials on farmland. TMACOG Director of Water Quality Kari Gerwin serves on the committee.

The two research groups that received grants have decided to collaborate on their projects to get the most out of the grant monies. The researchers hope to answer two important questions:

Does dredge offer any benefits in terms of nutrients (e.g., save cost on fertilizer) and soil biology (e.g., microbes, plants, bugs)?
Does dredge introduce additional contaminants to crops and drainage water compared to native soils?

A team from Wright State University in Dayton will investigate the value of planting a cover crop on the dredged soil. While dredged material holds organic matter and is generally considered fertile material, plants often fail to thrive when planted directly in it. The dredged soil has low nutrient availability and lacks microorganisms that can improve soil. It’s also frequently contaminated with toxins. The researchers’ plan is to leave one section of dredged material unplanted and to plant winter wheat on the other. Researchers propose to determine if a cover crop will increase the abundance, diversity, and function of beneficial soil microorganisms. They will measure the concentrations of contaminants and they will investigate whether runoff from the dredged soil is harmful to the environment. Planting will begin as soon as the site is prepared (planned for the first of November) on the Great Lakes Dredged Material Center for Innovation near downtown Toledo.

A Bowling Green State University team will investigate the value of adding dredged material to farmland and attempt to measure the ratio of dredged material to farm soil that generates the best result for farmers. They will be working in a greenhouse environment on the BGSU campus as well as at the center for innovation. The greenhouse experiments will compare corn crop yield using four different planting options: 100 percent farm soil, 10:90 dredged material to farm soil, or 20:80 dredged material to soil, or 100% dredged material. The experiment will test different phosphate ratios to determine if adding dredged materials will reduce the need for commercial fertilizer. The BGSU experiment also includes research into heavy metals found in dredged material. After harvest in both field and greenhouse experiments, crop yields and metal content in grains, legumes, and invertebrates will be determined.

DRIFT members will continue to offer feedback to researchers during the study period. At the next meeting in January the committee will focus on soil structure of the dredged materials.

Research team: from left, Shannon Pelini, Megan Rúa, Louise Stevenson, and Angélica Vázquez-Ortega. Dr. Rúa is from Wright State, the others are from BGSU.

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