Constructed Wetlands Show Promise in Managing Nutrients

Wetlands are among the most productive ecosystems in the world, comparable to rainforest and coral reefs. Now, modern agriculture is trying to capture some of nature’s wetland magic as a means to manage nutrients on the farm.

State and national corn organizations’ staff that work on water quality issues recently toured the Franklin Research & Demonstration Farm near Lexington, Illinois, to learn more about how research into “constructed wetlands” might provide another serious tool to help farmers manage nutrients like nitrogen and phosphorous.

The tour provided an educational opportunity for staff of the National Corn Growers Association and state corn staff representing Illinois, Colorado, Indiana, Kansas, Kentucky, Michigan, Minnesota, Missouri, Nebraska and Ohio who met in Bloomington, Illinois, to discuss initiatives to promote voluntary nutrient-management programs.

A constructed wetland is a man-made wetland that acts as a treatment system that uses natural processes involving wetland vegetation, soils, and their associated microbial activity to improve water quality. 

In the case of The Franklin Farm project, the wetlands being researched are designed to take tile water (not surface water) from nearby crop fields and slow down and clean the water, according to Ashley Maybanks, Mackinaw Science Specialist with The Nature Conservancy.

Wetlands function as nature’s kidneys, removing nutrients and sediment, as well as slowing down the flow of water before it reaches creeks, streams, and rivers. When placed near agricultural lands, constructed wetlands can catch and absorb nutrients from farm fields. At the Franklin Demonstration farm, researchers and farmers are learning how effective constructed wetlands can be, and specifically, the size and amount needed to help clean nutrients from water that passes through tile drains.
 

The Nature Conservancy is using Conservation Reserve Program dollars to test and collect data on constructed wetlands that are 3, 6 and 9 percent wetland size, relative size to the total drainage area. The various sizes have documented nutrient reductions of 30-46 percent from nitrogen and 45-91 percent for phosphorus.

The positive results are already leading to practical application and the adoption of more constructed wetlands on farms near Franklin Farms and in surrounding watersheds. To find out if constructed watersheds might be a good fit for your farm, you can contact The Nature Conservancy or your local Soil and Water Conservation District office.