A Nutrient Reduction Wetland is a strategically placed wetland designed to remove excess nutrients from field drainage before the water reaches rivers and other major waterways.

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Nutrient Reduction Wetland

Nutrient Reduction Wetland

Photo by Dawson, Justin and Timothy

Nutrient Reduction Wetland

Location: Near Gilbert, IA
Featuring: Kent Schwartz and Dr. Crumpton

As agricultural runoff slowly flows through wetlands, nitrogen and phosphorus can be removed through a combination of naturally occurring biological processes.

Iowa was once covered in wetlands. They provided a habitat for Iowa’s wildlife and filtered excess nutrients before they reached nearby rivers. When Iowa was settled, these wetlands were drained to create farmland. New techniques are now needed to remove the large amounts of nitrogen used in farming. Can wetlands be the answer?

Water enters this wetland from tile lines draining from one thousand acres of nearby agricultural land. Before water in this wetland flows into rivers that eventually lead to the ocean, the wetland will act like a purifying filter, reducing nutrients through a combination of particle settling, volatilization, and absorption. Some nutrients are also assimilated by plants, algae, and denitrifying bacteria in the water, which convert nitrate into harmless nitrogen gas. In Iowa, 150-300,000 wetlands would be needed for effective nitrogen reduction of the state’s agricultural runoff.

Kent Schwartz implemented this wetland 10 years ago with support from the Conservation Reserve Enhancement Program (CREP) to explore new methods for nitrogen removal as well as create habitat for wildlife. A water sampling machine takes sample of the water leaving the wetland every six hours; these samples are tested to monitor the nutrient levels in order to measure the wetland’s effectiveness.

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