More than 30 participants came out on June 27 to view the constructed wetland in Bureau County, Illinois and to learn updated research results from NREC-funded researchers. A number of farmers were in the audience to learn what they can do to held management nitrogen on their farms. Several NREC Council Members also attended, including Ted Mottaz, Jeff Kirwan, and Cindy Skrukrud.
Starting in the morning, Jill Kostel introduced the constructed wetland that her group built in 2016 a few miles southeast of Princeton, Illinois. Kostel is with The Wetlands Initiative and receives funding to demonstrate and monitor nutrient removal from the Big Bureau Creek watershed in Northern/Central Illinois. The kidney-shaped constructed wetland is an average of 18 inches deep and considered an “emerging marsh” and is fed by drainage tile from adjacent farmland. A surrounding buffer area is populated with a long list of pollinator plants. The wetland is such a size and depth as to not attract water fowl.
The Forum continued in Princeton and began with Lowell Gentry speaking about cover crops and edge-of-field practices for limiting nutrient loss on tile-drained land. Gentry stressed that farmers have choices on what works best for their individual production system and results from ongoing NREC projects are showing how effective nutrient management practices are at reducing tile nitrate loads.
One research project that Gentry reported noticeable results was the reduction of tile nitrates following a corn-soybean-wheat rotation in conjunction with cover crops. Tile nitrates were below 1 part per million (ppm) after growing a cover crop (radish and turnip) following winter wheat harvest – down from as high as 10 ppm earlier that spring. The following corn yields were down just slightly on the field with the abundant cover crop of radish and turnip and researchers are looking in to what caused it. Gentry said that it may be possible to have too much of a good thing because the extra time for cover crop growth after wheat really helped produce huge amounts of cover crop biomass.
The illustration below shows the field design and crop rotation for three crop years and the position of 6 woodchip bioreactors. On this one farm, researchers are simultaneously evaluating 4 production systems: corn-soybean-wheat with cover crops; conventional corn-soybean; and continuous corn with and without a cover crop.
Laura Christianson continued with the Forum talking about the use of edge-of-field bioreactors and explaining how bioreactors work to remove nitrates from fields. Tile water is routed through the bioreactor; woodchips inside convert nitrogen in tile water to benign nitrogen gas. Woodchips are preferred since carbon is readily available. Bioreactors on half of all tile-drained acres are estimated to reduce nitrate losses by 25-percent at a cost of $2.20 per pound of nitrogen saved.
The day concluded with a presentation from Shalamar Armstrong on the timing of nitrogen application and a lively question and answer period.