Inside Sukup Hall at Iowa State University, you’ll find the Department of Agricultural and Biosystems Engineering; a place where you’ll find researchers are digging into the role agriculture may or may not be playing in a growing medical concern.
“These PVC pipes are columns of prairie strip,” says Jared Flater, a postdoctoral research association in Agricultural and Biosystems Engineering at Iowa State, as he shows the research being done inside the lab.
“This project is looking at antimicrobial resistance and how it occurs as a result of agriculture,” says Adina Howe, associate professor, Agricultural and Biosystems Engineering at Iowa State. “This is an area where data is really missing and we’re connecting the dots between how we manage agriculture and how antibiotic resistance in the hospitals might be occurring.”
Focusing on Manure from Hogs
Howe says her team’s work is focusing specifically on the use of antibiotics in hog production and the possible impact on antimicrobial resistance.
“It could occur in a hospital from overprescribing and use of antibiotics, it could be also occurring from usage in agriculture from producing animals, keeping them safe and healthy, so that we can use them for global food,” says Howe.
The research is two decades in the works, but now Howe’s team is taking a different route, focusing on manure applied to crops.
“We have found also that there are potentially ways to manage that occurrence and emergence of this resistance,” says Howe.
By focusing on hog manure applied as a fertilizer on farm fields, the work is honing in on a specific practice widely used in agriculture today.
“As animals are fed antibiotics it goes into their guts, it gets excreted into the manure, and we apply this manure on to soils,” Howe says. “One of the concerns is it then rains, and that rain pushes the antibiotics into our waterways. And so the question is, how can we manage these points where resistance might be occurring?”
Conservation Prairie Strips
That’s where the work of Howe’s team comes in, working to intercept that water flow and treat antibiotic resistance bacteria that might be flowing in a field.
“Part of our question is, ‘how much soil profile affects the amount of antibiotic resistance in our water that filters through the soil?’ Another part of our experiment is evaluating how the type of manure affects antibiotic resistance,” says Flater.
Samples of conservation prairie strips are extracted from Buchanan County, Iowa, farm fields and then brought back to the Iowa State lab.
“We simulated runoff from here,” says Flater. “We’re pretending that a field that got manure applied had a big rainfall event, the water picked up that manure and is washing it towards waterways.”
He says the idea is the prairie strips intercept water that’s flowing over land, helping remove the antibiotic resistance genes.
“So, what we did was we made a dilute solution of either digestate or manure or mineral fertilizer, we use this needle cap to apply it, so that it came out in about 15 minutes,” he adds.
As the solution filters to the bottom of the cylinder, the lab can then quantify the amount of antibiotic resistance genes they find.
“We’ve found 15 to 20,” says Flater. “The trick is identifying the genes that are specific to manure and that are already present in the environment.”
Soil Structure and Soil Type
The researchers have also found soil structure and soil type are also important when looking at the role the natural environment can play in the overall picture.
“What we’re kind of realizing now is the soil structure could have a really big impact on how fast these antibiotic resistance genes move through the system, and how well they might be removed,” says Flater.
Goal is to Manage, Not Eliminate
As the data washes in, Howe says the goal isn’t to eliminate antibiotic use in animals or people.
“What we need is to be thoughtful in how we sustainably manage it, and also work with stakeholders like farmers and other agricultural managers to sustainably treat and mitigate this risk that we know is something important to all of us,” Howe says.
Funded by USDA, the Iowa State research could reach beyond Iowa farm fields.
“I think this research has a huge impact,” says Howe. “We’re filling in data that currently does not exist. And without data, you can’t make a decision. So, one of the things we’re really invested in is making decisions easier for people who need to make decisions.”
As the team sets its sights on more advancements, the Iowa State University lab is creating possible solutions with tools already used on some farms today.
“My next sort of theory is we need to retain the water on the lands before the water comes off, to allow them to sort of be affected by the native soil microbial community and, hopefully, the antibiotic-resistant bacteria are out-competed by the native soil bacteria,” says Flater.
