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Serving: IA

The next step in reducing nutrient loss

Tile drainage water is directed into lateral drain tile installed parallel to a riparian buffer
SATURATED BUFFER: Tile drainage water is directed into lateral drain tile installed parallel to a riparian buffer. Water moves across the length of the buffer removing nitrate.
Using edge-of-field practices can improve water quality.

What will it take to get cleaner water in Iowa? To get 6 million acres of cropland treated by bioreactors? Seven million acres treated by nitrate removal wetlands? That’s one of the scenarios suggested by Iowa’s Nutrient Reduction Strategy. So far across Iowa, only 950 acres are treated by bioreactors and about 42,000 acres have wetlands.

Why use bioreactors, saturated buffers, constructed wetlands, controlled drainage and other edge-of-field practices? Such practices are expensive to install. Why not just plant all of Iowa’s row crop land to no-till and strip till? Wouldn’t that solve Iowa’s water quality problems?

The answer is no, according to scientific research in which the NRS is based. Iowa State University ag engineer Matt Helmers said there are benefits from no-till for reducing soil and phosphorus loss, but little to no reduction in nitrate loss with no-till vs. conventional tillage.

“There are definitely soil quality, soil health, soil erosion and particulate phosphorus control benefits with no-till, but not a nitrate reduction benefit,” he said. “We need to see a lot more no-till and strip till used. But even if we did go to all no-till in Iowa, we would still need to use some of these other practices for nitrate reduction.”

In-field and edge-of-field
Widespread use of cover crops would also help reduce nitrate loss to waterways. Iowa has about 720,000 acres of cover crops, and needs 12 million, according to one scenario in the NRS. The way to dramatically increase cover crops is to find a way to make them pay, and that means grazing them. “Iowa needs a lot more cattle,” noted Helmers, who specializes in water resource management and works with the Iowa Learning Farms program.

ILF is holding a series of field days this summer on edge-of-field practices beginning July 17. For updates and details, visit

Last winter ILF hosted a group of 12 farmers in Ames to discuss issues surrounding edge-of-field practices and nutrient reduction. Overwhelmingly, the group felt when it comes to edge-of-field practices, it’s critically important that the practices are targeted to sites where they would provide the most water quality benefits. As Tim Smith of Wright County said, “There are a number of practices, and not every practice is going to work everywhere.”

Put right practice in right place
To target edge-of-field practices through government cost share, you need to work with the local Soil and Water Conservation Districts. Several farmers in attendance serve as SWCD commissioners and agreed it’s the district’s responsibility to help target these practices rather than distribute funds on a first-come, first-served basis. “If you’re not targeting as commissioners then you’re not doing your job,” said Dennis Carney a Cerro Gordo County commissioner and vice president of Conservation Districts of Iowa.

Rick Juchems, a Butler County commissioner, said his SWCD tried to target conservation practices, but farmers weren’t interested. “We can target and send out letters, but they still have to want to do it,” he added.

Farmers in the ILF group said edge-of-field practices that take the least amount of land out of production are more likely to be adopted. On the other hand, those practices aren’t very visible and would likely have limited public support. The conversation then turned to nitrate removal wetlands.

Installation of man-made wetlands
Constructed wetlands have other benefits beyond water quality improvement. Wetlands can be a highly visible way to draw positive attention to conservation efforts, while providing a benefit to the community by creating recreation areas and increasing wildlife habitat. Some farmers are interested in wetlands because they improve the beauty of the landscape. Others see wetlands as a good way to take row crop acres out of production that are underperforming.

WETLANDS: Shallow in depth, wetlands allow surface runoff water to slow down and deposit sediment. On average, wetlands can remove 40% to 90% of nitrates from water.

Greene County farmer Chris Henning has seen an improved average yield after converting 10 low-producing acres into a wetland. “Wetlands get a lot of attention, and nonfarmers are applauding it as ‘regenerative’ farming,” she said.

The group was introduced to some of the newer technology being developed related to drainage systems in the Midwest. ISU’s Helmers shared with them findings from Transforming Drainage, a multistate collaborative project focused on increasing the resiliency of drained farmland through controlled drainage, saturated buffers and drainage water recycling.

While many of the farmers felt that saturated buffers might work well in areas of the state where there is a lot of tile drainage, they were less convinced that controlled drainage and drainage water recycling could work in Iowa.

Seth Watkins of Page County was intrigued by water recycling: “As a livestock person, irrigating out of our lagoons is a normal management practice. I think drainage water recycling could be a viable concept for our area.”

Helmers acknowledged controlled drainage and drainage water recycling have potential for some areas in Iowa, “but a lot of questions still need to be answered.”

Removing land from production
Taking land out of production is one of the biggest barriers to installing edge-of-field practices. But practices like saturated buffers and bioreactors have minimal land impact and may be more readily adopted than practices such as wetlands and prairie strips.

A larger takeaway from the ILF farmer discussion was that, despite having made some progress toward NRS goals, there is still much that needs to be understood about edge-of-field practices if Iowa is to meet the goals. More outreach, education and research is needed before Iowa can hope to see voluntary large-scale adoption of these practices. Watkins even questioned whether large-scale adoption of edge-of-field practices could be achieved through voluntary compliance. No one in the group had an answer to that question.

For more information about edge-of-field conservation practices, contact [email protected] or visit

TAGS: Water
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