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Wetlands top list for better water quality

There was a time when farmers considered natural wetlands to be wasted land, since they couldn’t be farmed. That’s not the case anymore, with all the emphasis on nutrient reduction in water that leaves the farm.

Wetlands top list for better water quality

There was a time when farmers considered natural wetlands to be wasted land, since they couldn’t be farmed. That’s not the case anymore, with all the emphasis on nutrient reduction in water that leaves the farm.

In fact, as farmers, conservationists and concerned groups continue to look for ways to make water cleaner before it leaves the farm, they’re actually creating wetlands where they fit the landscape.

“Restored or constructed wetlands — properly placed — would be my No. 1 choice of all the edge-of-field practices available to reduce the amount of nitrates in water that leaves the farm,” says Maria Lemke, an aquatic ecologist with The Nature Conservancy in the Mackinaw River Watershed in Illinois. “The other practices have their niches, too, and there are places wetlands won’t work. But where they fit, they have so many advantages.”

Lemke and TNC have worked a number of years with researchers and farmers alike to find and establish practices in the Mackinaw River Watershed that will cut the amount of nitrates in water.

She’s been part of a team that’s helped encourage and assist farmers in speeding adoption of soil-saving practices like grassed waterways, stream buffers and strip till in an effort to improve water in two water-supply reservoirs that serve 80,000 people in the city of Bloomington, Ill.

“We got more practices on the land, but what we found was, after seven years of monitoring, we had no significant changes in nitrate-nitrogen in the water,” Lemke says. “We knew then we had to focus on practices that specifically reduce nitrates coming from tile water.”

Lemke offers half a dozen reasons to consider wetlands as a high-priority practice for nitrate removal if they fit your land:

High rate of nitrate removal. “We’ve found a wetland that’s 5% to 6% of the area being drained by tiles removes about 50% of the nitrates from tile water,” says researcher David Kovacic of the University of Illinois. “Wetlands with that ratio give you the most bang for the buck — larger wetlands have diminishing returns.”

“Research at the Franklin Family Research and Demon-stration Farm in McLean County [Ill.] shows us these wetlands work,” says Lemke. “We think we’ve got the answer to the question of how large wetlands need to be to effectively reduce nutrients from tile water. Now we have to figure out how to expand their use to a watershed scale.”

Underground and surface water capture. The focus is tile-drained water, since that’s the missing piece for nitrate removal after good soil conservation and runoff measures are taken. Since nitrates are soluble in water, both underground and surface waters need to be treated before leaving the farm. While a bioreactor may remove as much nitrate as a wetland, it will only treat tile water. Soil- saving practices that keep soil in place do a good job for phosphorus reduction in streams, but don’t capture the nitrates in tile waters. Restored or constructed wetlands, on the other hand, can remove nitrates from both surface runoff water and tile water that is directed into the wetland.

Low-maintenance, long-lasting. Properly designed wetlands will function for many years with very little maintenance. Bioreactors and restored oxbows have a shorter lifespan.

Top-shelf wildlife habitat. Some wildlife experts say no single practice offers more wildlife habitat than a wetland. Habitat isn’t limited to amphibian and migratory waterfowl — pheasants, deer, raccoons and many bird species frequent wetlands as well. Of course, an underground bioreactor has grass as a surface, but is very limited in habitat.

Landscape diversification. Since wetlands offer shallow water, plants that thrive in that environment are encouraged to grow there. Those plants and water also attract a diversity of animal life.

Payment incentives available. While most water-quality practices qualify for some kind of incentive payments, USDA has a number of programs that may pay most of the costs of restoring or constructing wetlands. One USDA program, the Conservation Reserve Program, pays half the cost of building the wetland, offers a $100-per-acre signing incentive and gives annual rental payments for up to 15 years.

Betts writes from Johnston.

Farm-related funding for sustainability

Agriculture and conservation-related companies and foundations are funding a number of water quality projects and practices across the country. For example, the Coca-Cola Foundation is supporting The Nature Conservancy’s farming partnership work to restore oxbows, plant cover crops and install demonstration bioreactors in the Boone River Watershed of Iowa. The World Wildlife Fund/Coca-Cola Partnership is funding constructed wetlands in watersheds of Cedar Creek in Iowa, Root River in Minnesota and Mackinaw River in Illinois.

“We’ve worked with The Nature Conservancy and other partners to support water quality and water conservation projects for a number of years on agricultural land to return clean water to nature for communities,” says Jon Radtke, manager of water resources for Coca-Cola North America.

“One of Coca-Cola’s sugar suppliers, Archer Daniels Midland Co., sources corn from farmers in the Mackinaw watershed basin in McLean County in Illinois, where the new wetlands will be built this year,” he says. “Coca-Cola understands that a healthy agricultural supply chain is critical to business success and essential to community well-being.

“Not only will the tile drain-treatment wetland support improving water for the city of Bloomington, it will also help us toward meeting our goal to return fresh water to nature, balancing our water use at bottling operations,” Radtke says. “We are developing farming partner programs in key regions with suppliers and the conservation community that will help improve current practices to optimize productivity and decrease costs to farmers. These programs also aim to serve as effective watershed replenishment projects.”

In-field choice: cover crops

The Nature Conservancy has been offering incentives to farmers to try cover crops across the Midwest because they have so many potential advantages. “I’d put them at the top of the list for practices you use within the field to reduce nitrate and phosphorus losses,” Maria Lemke says.

“Research suggests they’re one of the few working cropland practices that significantly prevents both N and P loss,” Lemke says. “According to Iowa State University, they have the potential to cut both N and P concentrations by 30%. Because phosphorus attaches to soil particles, as cover crops hold soil in place, they keep phosphorus in the field.

“And for nitrogen reductions, top growth is good, but what’s really important for them is what you don’t see — their roots. Those roots sequester nitrogen, build organic matter and build soil structure — all those things help with better retention of water. The longer you hold water in the soil profile, the longer you have for the crop to use nitrates in that water.”

Ross Fogle, a resource conservationist with the McLean County (Ill.) Soil and Water Conservation District, says the Franklin Demonstration Farm is working as planned. “They’re in their third year of cover crops here, and people are watching. They relate their own cover crops thinking to the demonstration farm. There’s definitely more acceptance now than there was a few years ago,” Fogle says. “Stopping soil erosion is their first thought in most cases, but I think people are also looking at trying to save on nitrogen inputs, and building organic matter in their soil.”

Lemke says the timing and amount of fertilizer applied is also important. “It will take a combination of practices. We’re not downplaying the importance of sound nutrient management and other practices — just pointing out which ones might have early impacts,” she says.


N REMOVAL COMBO: Constructed wetlands and cover crops combine to remove nitrogen from cropland in tests at the Franklin Demonstration Farm in McLean County, Ill.



COVERS COUNT: Cover crops build organic matter and remove nitrogen from groundwater, say conservationists Ross Fogle and Maria Lemke.

This article published in the August, 2014 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2014.

Best Management Practices

Nutrient Management

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