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Showing posts with the label nitrates

Wood Chip Bioreactor Controls Tile Line Nitrate Load

The Dudley Smith research farm in Illinois is tiled and wired. Todd Gleason has more on how the University of Illinois is doing nitrogen loss research near Pana.

Farmers gathered this week for a peek at the nitrogen loss control methods installed in Christian County. It’s a farm that rolls just a bit, but is pretty typical for the area other than the pastures on a portion of it. They came to hear from Laura Christianson. She’s a University of Illinois Crop Scientist, “At the Dudley Smith farm we have a wood chip bioreactor installed. A wood chip bioreactor is a little mini water treatment plant to clean nitrate out of tile drainage. The thing that makes the Dudley Smith bioreactor different is that is has baffles inside it. So, rather than the water just running straight through the wood chips, like most bioreactors, this bioreactor has baffles in it to make the water move in more of an S shape to improve how much nitrate is taken out of the drainage water”.

Early indications are the baffle is working as hoped. Wood chip bioreactors, even without the baffles, can remove between 20 and 40 percent of the annual nitrate load from a tile line. It’s technology farmers are interested in seeing and hopefully, says Christianson, deploying, “I think farmers are interested in wood chip bioreactors because it is something they can do that doesn’t impact their production practices. It is an edge of field practice, so you can keep on in the field however you are comfortable, but this catches that nitrate at the edge of the field before it goes down stream”.

A bioreactor is pretty simple to build. Use a backhoe to make a trench near the end of the tile, put a plastic liner in the trench, fill it with wood chips, be sure to have control structures on the inlet and outlet, and cover it with dirt. The chips will need to be replaced about every 10 years.

Iowa Court Decision on Field Tiles | an interview with Jonathan Coppess

The Iowa Supreme Court has ruled drainage districts in the state cannot be sued for the cleanup of nitrates in drinking water. Justice Thomas Waterman authored the majority opinion, writing that policy deciding who pays for nitrate removal is the jurisdiction of Iowa lawmakers. This was a win for the drainage districts says University of Illinois Agricultural Policy Specialist Jonathan Coppess. However, he says the Clean Water Act implications of the suit, about whether or not field tiles are point sources that can be regulated, remains to be addressed.

“So the big question under the Clean Water Act, as I understand it, is the Des Moines Water Works is claiming that the agricultural stormwater exemption under the Clean Water Act does not apply to drainage districts. In this case, because once it comes through the pipes it becomes a point source.” –Jonathan Coppess, Agricultural Policy Specialist - University of Illinois

Again, the decision in the Iowa courts is that only lawmakers in the state can determine who pays for the cleanup of nitrates from drainage districts. It did not address issues related to whether or not field tiles should be subject to regulation under the Clean Water Act.