SALEM, Ohio — Reaching Ohio’s 2025 target for improving Lake Erie’s water quality will be even more challenging than expected, according to a recently completed study led by Ohio State research teams.
Phosphorus runoff from farmland is a major cause of harmful algal blooms in Lake Erie, experts say. The U.S. and Canada set a goal in 2012 to reduce the phosphorus coming into the lake by 40% by 2025.
“We always knew meeting the 40% was going to be a heavy lift,” said Gail Hesse, director of the Great Lakes Water Program for the National Wildlife Federation. “This project shows it is going to be a heavier lift than we thought.”
Ohio could still meet the 40% target, but Jay Martin, professor in Ohio State’s Department of Food, Agricultural and Biological Engineering, estimated about 80% of farmers would have to start using the most effective combinations of conservation practices.
“It kind of informs a sense of urgency,” Hesse said. “We don’t want to just sort of go along as we’ve gone along … it is going to be important to ramp it up.”
Over three years, researchers used the Soil & Water Assessment Tool to create five models based on the Maumee River Watershed. With these models, they tested both individual practices and combinations of best management practices for reducing phosphorus runoff. They averaged the results across the five models.
Researchers used surveys and input from the farming community to come up with relatively realistic scenarios.
The study concluded that subsurface placement for fertilizer was one of the most effective ways to reduce runoff. No single practice was effective enough to meet the 2025 target by itself, however.
The study looked at both total phosphorus and dissolved reactive phosphorus. Total phosphorus includes dissolved reactive phosphorus.
Martin said dissolved reactive phosphorus has made Lake Erie’s algal blooms more severe over the years.
While all of these scenarios did reduce phosphorus runoff, the only scenarios that met the goal for reducing total phosphorus included a mix of buffer strips and in-field management, like cover crops and subsurface placement. The scenario that met the total phosphorus target used the same practices as one that came close, but did not meet the target. The difference was in the adoption rates.
No scenario met the goal for reducing dissolved reactive phosphorus.
Researchers said this shows the need for more research into practices that focus on reducing dissolved reactive phosphorus. Martin said these would be processes that hold back or filter water. Researchers also said they may need to study more combinations of practices to keep finding effective combinations.
The study was not connected to H2Ohio, but researchers said it was fortunate that their results and details on the H2Ohio initiative came out around the same time.
They said it is still difficult to know how many farmers need to adopt better management practices to meet the goal, because it is hard to know exactly who is already using best management practices and who is not.
Hesse said some of H2Ohio’s programs will help gather information on the situation as it is, and will encourage more farmers to adopt conservation practices.
Researchers also noted that it will be important to identify areas that have the most potential for phosphorus runoff and use practices there. H2Ohio programs will help farmers develop plans based on what is the most effective for their fields.
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