Field day studies struvite as alternative to phosphorus

By Katie Zelechowski


Standing in a soybean field in Streator, David Isermann delivered a welcome message through the lens of a video camera, talking to farmers who would later tune in online to this field day.

The LaSalle County Farm Bureau president's introduction kicked off the second field day in a series offered through the Illinois Farm Bureau’s Nutrient Stewardship Grant Program. The main topic for discussion was using struvite to replace traditional phosphorus applications in the field.

Isermann Farms is owned and operated by David and his son, Jim, who also works as a field manager for the Soil Health Partnership in Illinois and Wisconsin. The farm has been a no-till corn, soybean and hay operation since the 1990s. A number of years ago, the family added livestock, allowing them to utilize a cover crop grazing system that has proven to be economically sustainable.

As they have adapted new practices on their farm, the Isermanns have continued to look for ways to improve soil health through nutrient stewardship. One way they’ve done this is through research with Andrew Margenot, assistant professor with the University of Illinois Crop Sciences Department. Margenot is looking at using struvite as an alternative source of phosphorus in agricultural production.

The project utilizes wastewater from water treatment plants in the Chicago area, extracting phosphorus in the form of struvite, which can then be applied to crop fields.

Julie Hewitt, executive director for the Illinois Nutrient Research and Education Council (NREC), said the best part of using struvite is that it closes the loop of getting water from point sources that emit nutrients, such as treatment plants, to agricultural production.

The project is in its second year of four, but preliminary findings show encouraging results.

In phosphorus-deficient soils, a 50-50 blend of struvite and monoammonium phosphate (MAP) appears to optimize corn and soybean growth while reducing the risk of phosphorus runoff.

In soils with adequate to high amounts of phosphorus, corn yields are unaffected by up to 75% struvite substitution for MAP, while double-cropped wheat and soybeans are unaffected by up to 100% substitution.

“It’s just as effective as any other form of phosphorus,” said David Isermann. “I think that it’s going to be something we can look at in the future as a way to utilize that phosphorus that would otherwise be lost.”

Margenot said he sees struvite as having the potential to be a triple win because it utilizes phosphorus from point sources, allows captured phosphorus to be reused as fertilizer on farms and mitigates the risk of nutrient loss in crop fields.

“Of course, we need to test that hypothesis. That’s why we’re here,” said Margenot, adding that he sees tremendous value in working directly with farmers like the Isermanns on field trials. “Researchers can and should start there to inform their research.”

In addition to looking at struvite’s effect on crop production during the field day, the Isermanns also invited Margenot to take a deep-dive into soil health on their farm via a soil pit.

“What I’m really interested in is knowing if I am providing everything my crops need throughout the year, particularly since I’m not doing tillage,” said Jim Isermann. “We’re wanting to make sure we’re on the right path.”

Based on feedback from Margenot and observations of healthy root depth and earthworm activity, Jim concluded their current field management has been working.

“This soil pit is really helping me understand that I’m probably doing alright without (tillage),” he said.

Building those connections between researchers, farmers and other organizations to find common solutions is an integral part of the Illinois Nutrient Loss Reduction Strategy (NLRS), which IFB’s Nutrient Stewardship Grant Program supports. The collective efforts of Farm Bureau, U of I, Illinois NREC, and the Soil Health Partnership made the research at Isermann Farms possible.

Although coronavirus concerns will keep farmers from attending the 2020 NLRS field days in person, IFB Director of Environmental Policy Lauren Lurkins said she sees the online information reaching broader audiences.

“Although we miss seeing our farmers face-to-face through these events, having our field day materials online helps us get research into the hands of farmers across the state, rather than being limited to local audiences,” said Lurkins.

With such easy access to results from his own on-farm studies through this year’s virtual field day, David said he hopes other farmers will take a look and be inspired to adopt similar practices on their farms. He said no matter how small the start, it’s important to continue to look for innovative ways to manage nutrients on the farm.

“I’d encourage people to pick something and try it,” he said.

To learn more about research at Isermann Farms, visit

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