Lakes are an important source of drinking water and tourism dollars in many places across the country. That’s why late summer toxic algal blooms are more than just an eyesore -- they’re a threat to public health, the economy, and the ecosystem.
Nutrient runoff from farms is often a big driver of these harmful blooms. Now a group of Ohio scientists is trying to figure out how to keep nutrients on the farm and out of Lake Erie.
On a wheat field in Paulding County, Ohio, USDA researcher Kevin King shows off water sampling gear to a group of agricultural leaders and experts. His team has placed this machinery on nearly 30 Ohio farms.
The goal of the research is to track nutrient runoff from the farm field. Farmers add these nutrients (fertilizer, primarily composed of nitrogen, phosphorus, and potassium) to help the crops grow.
This study is important because these nutrients drive the harmful algal blooms that kill fish, sicken pets, and taint drinking water for the millions who depend on Lake Erie and other affected waterways.
The study’s lead investigator, Libby Dayton from Ohio State University, says they’re naming this project “On Field Ohio.”
“The premise and heart of it is we want to figure out how to keep nutrients on the field, and we want to figure out how to keep water on the field. We think that if we keep what needs to be on the field on the field it will reduce the transport off the field, and that will be a big help toward improving water quality.”
Dayton and colleagues have three years and two million dollars to determine a sort of “best practices” guide for keeping nutrients on the farm field. Specifically, they are looking to contain phosphorus, the key driver of freshwater algal blooms. Ohio farmers, along with the United States Department of Agriculture, are footing the bill.
The lake’s algae problem isn’t new. Back in the 1970s, discharge from sewage treatment plants was largely to blame. Sewage contains many of the same nutrients found in fertilizer runoff. In order to mitigate the problem, cities upgraded their filtering systems and companies reformulated detergents and other products to choke off the nutrient supply. The lake got better as a result.
“And then that’s when agricultural businesses started to shift,” says chemical engineer and former EPA researcher Steve Duirk from the University of Akron, “and that’s the reason we started to see these blooms come back, and as bad as they were in the ’70s. And it’s almost solely attributed to agriculture.”
No one knows for sure what changed in agriculture, but research suggests heavy rains plus certain fertilizer and soil management techniques widely adopted over the last decade have spurred the blooms. This is exactly what Dayton and her team are investigating on the farm. They’re taking samples from some of the 70,000 farms engaged in all sorts of management practices along the Erie shore.
Terry McClure is a fifth generation Ohio farmer who owns the 3,800-acre farm that researchers and ag experts now gather around. “This is soft red winter wheat,” says McClure. “So think crackers, think Triscuits, think doughnuts. That’s what we make.” He calls his farm “rotational no-till,” which means they don’t disturb the soil structure with deep plowing. McClure also uses cover crops, plants grown for the purposing of maintaining soil quality. They’re known to reduce runoff and help keep nutrients on the field.
There are a lot of questions about why agriculture may be to blame for the algal blooms in Lake Erie. That’s why McClure is participating in this study. “If you might be a part of the problem," says McClure, "you ought to be part of the solution.”
McClure notes that farmers have been saying for years that the lake’s algae issues can’t possibly be their problem because they know they’ve been using less and less phosphate. “Something’s going on here that we don’t understand,” he says.
Dayton and other researchers point to a specific water-soluble type of phosphorus that is behind the blooms. “We’re having issues now where the dissolved portion of the phosphorus has been creeping up, and so that’s one of the things that we’re looking at,” she says.
Algae love dissolved phosphorus. It’s a ready meal. Even tiny amounts of the runoff are problematic. USDA’s Kevin King explains that what’s causing the problem is only about half a pound of phosphorus runoff per acre of agricultural land. “When a farmer applies 30 to 40 pounds per acre and they’re only losing a half a pound to a pound, but that’s what’s causing the problem, that’s…what we’re working with here,” says King. “It is a very narrow window.”
It’s too early for answers, but study researchers say the combination of no-till and cover crops, like this wheat field of McClure’s, looks like a promising way to rein in the dissolved phosphorus.
Here’s the good news: Akron scientist Steve Duirk says since Lake Erie is so shallow, if ag experts get this right, and the weather cooperates, it would only take about two years for the lake to flush out and rebound -- again.