Edge-of-field system prevents phosphorus from entering nearby Fox Lake

Gloria Hafemeister
Nancy Kavazanjian describes how the unique edge-of-field phosphorus removal from tile water system works to improve water quality and benefit nearby Fox Lake.

FOX LAKE – Charlie Hammer and his wife Nancy Kavazanjian have always been interested in water quality, conservation and improving soil fertility.

The fourth-generation farm that started with 173 acres near Beaver Dam and has grown to over 2000 acres is an example of how farmers can use innovative ideas to protect area lakes and streams while still improving their soil and yields.

Last week the couple hosted a meeting of the Dodge County Healthy Soils-Healthy Waters organization and provided a tour of their latest project, a phosphorus removal system designed to keep phosphorus from entering nearby Fox Lake.

Hammer loves to connect with a network of like-minded farmers and friends to share innovative successes and failures.

“Both Nancy and I encourage young farmers to find their network of people to share ideas that can help improve your business and your conservation practices,” he says.

He further notes, “We’ve added small grains and cover crops to our crop rotation, along with variable-rate nutrients to improve crop fertility and water quality, but we wanted to take the next step of filtering our tile water.”

Their project is an example of why it takes so long to come up with good ways to capture nutrients. 

The farmers in the Healthy Soils group have learned, from experience, that there are multiple ways to prevent erosion and improve soil and a singular approach is not necessarily the answer.

As farmers know, even the best ideas face complications with extreme weather challenges and that’s why groups like the Healthy Soils-Healthy Waters organization look at a variety of methods for protecting waterways and holding nutrients in the field where they do the most good.

Kavazanjian says the idea for their latest project started when they were visiting with her brother, a professor at Arizona State University, about protecting nearby lakes and keeping nutrients in the field. It was that dinner-table discussion that led to the installation of the Arizona mining water reclamation technology to its first on-farm trial in the Dodge County field.

While phosphorus is an essential nutrient for crops if it runs off into lakes it may cause toxic algae growth, contaminated water supplies and oxygen-scarce “dead zones” where most organisms can’t survive.

Other significant sources of phosphorus water pollution can include: discharges of storm water and municipal, industrial, and septic wastewater; and soil erosion that delivers phosphorus to nearby waters. For that reason, local communities and lakes associations have taken an interest in the project that was funded, in part, by the American Soybean Association and the Walton Family Foundation.

Nancy Kavazanjian stands in a field of pollinator plants that she and her husband Charlie Hammer established in an area next to their soybean and corn fields.

Local lake associations were eager to join in the effort and had hopes of installing more systems like it.  The couple, however, urged them to wait to see how this system worked first before jumping in to build more systems.

Like any technology, it may sound good on paper but when put into place there are other factors like weather challenges and other unknowns.

They selected the edge of a 70-acre field that tile drains into a wetland then into nearby Fox Lake.  A portion of the field had received manure fertilizer over the years and another portion had not.

The phosphorus filter design includes a smaller geomembrane-lined, rock-covered filter pit that contains steel slag. Field tile lines, with shutoff valves, feed the water into this slag filter then into a larger open holding pond where the phosphorus precipitates out.

“Once the soluble phosphorus in the water hits the steel slag, a chemical reaction begins to remove the phosphorus out of the water,” Hammer says.

While the idea is good, the field they selected did not have as much phosphorus runoff as might have been expected. The family had already been using cover crops and no-till and other practices to reduce the level of phosphorus.

“One thing we’ve already learned from this project is that our current agronomic and cover crop practices show a reduced level of phosphorus,” Hammer says.

The innovative Phosphorus Reduction System uses several water flow control devices and blast furnace slag to reduce the concentration of phosphorus in the water within their drain tile line that all eventually goes into Fox Lake.

The system was built with valves in the tile lines that open and close to control the flow.  It is designed to handle 3000 gallons per hour.

Water is sampled as it goes into the system and out. 

Getting the system up and running took more time than they anticipated. The extreme wet soil and abundance of rain in the fall of 2019 delayed construction. Then this spring the filter bed didn’t work because the filtering material was too fine and it plugged. 

Hammer points out that a similar system in place in Indiana has had more success with a different filtering material that also includes metal filings.

Revamping the system experienced delays last year partly because of slow downs due to COVID that led to delays in getting supplies and offices of advisors and consultants working on the project were closed for a time.

While the wet weather presented challenges when they built the system this dry year has also prevented the system from working exactly like it was intended.  While the hole that accumulated water last year was full, this year it is empty as little water is flowing through the lines.

Further, they found that because the slope in the large field is so gradual the tile flow was not quite like they would have expected. 

As a result they are looking at relocating the entire system to a different site in the field, closer to the wetland area. Hammer believes this would be a more effective way of capturing phosphorus before the water would then be discharged into the wetland where it would filter even more before eventually entering Fox Lake.

The couple has not given up on the concept of how the system works. They simply say it needs to be tweaked to work as it is designed to do.

Should the project prove to be successful, it could be replicated to reduce Phosphorus outputs on other farms that use drain tile.

Besides their conservation efforts Hammer and Kavazanjian have made a huge effort to provide the needed habitat for pollinators by providing land for a pollinator strip of native wildflowers and milkweed. They provided a tour of that area during last week’s field day as well.

The goal of the Healthy Soils-Healthy Waters group, when they started five years ago, has been to get 50% of the county’s farmland protected with cover crops. They now understand the importance of getting away from a singular approach and looking at cover crops in combination with other conservation measures.

The group held a field day in late August and will host a larger public demonstration field days in October on Fox Lake and Lake Sinissippi area farms.