Bioreactors are a relatively new conservation practice, you put them on the edge of a farm field and they grab the excess nutrients leaving.
Ten years ago, the Iowa Soybean Association (ISA) installed the very first bioreactor in the state. It was funded by Ag Clean Water Alliance and it's on the land of Greene county farmer, Mike Bravard, who says it's hidden on the back side of his field. If you didn't know about it, you wouldn't know it was there.
Bravard says, "We worked with our local NRCS office and then with the Soybean Association and they just kinda said, 'What do you think?' And I said, 'Let's give it a try.'"
This month the Iowa Soybean Association recharged that bioreactor for the very first time, they last about 10 to 15 years, and they wanted to see what that process is like.
Water quality data in the state's four bioreactor studies shows an average nitrate reduction of 43 percent. This bioreactor site has seen the practice reduce nitrates anywhere from 20 to 60 percent.
ISA Senior Environmental Scientist Chris Hay says, "With the nutrient reduction strategy, we're trying to meet 41 percent reduction from non-point sources or basically agriculture. And so, there's a number of different ways that we can do that but bioreactors are fitting in this class of edge of field practices, which are really important way or cost effective, and then some of the best performing practices we've got to do that."
At the recharging event, the practice site was on display. The soil was pulled up and the wood chips underneath were replaced with new wood chips. Bioreactors are put in spots where farmers direct water flow off the farm. By placing them there, the water is forced to run through the wood chips, which causes the nitrates in the water to react there instead of continuing on downstream.
ISA Director of Environmental Programs Roger Wolf says, "We want to put the practices where they're going to give us the biggest bang for the buck, and so not every tile line is suitable for a bioreactor. There's going to be some tile lines that might be emitting a lot less than others, so we want to put the practices where it makes the most sense."
On the farm, Bravard says the process was good to see up close as one of the newer tools in the farmer toolbox for reducing nutrient loss. He often has people asking how well it works.
One of these bioreactors can treat about 100 acres of tile drained land.
ISA Environmental Projects Manager Keegan Kult says, "A typical installation is anywhere from $8,000-$12,000 on bioreactors, depending on the size that we're treating. To cover those costs because the benefits are all occurring downstream there's quite a few financial incentive programs."
Kult says there are state and federal cost shares to help with the price and there are priority watersheds with the Iowa Nutrient Reduction Strategy.
Those are needed because there is no direct benefit to the farmer. A bioreactor only helps the people downstream. And when farmers are just trying to break even, coming up with $10,000 can be tough.
Wolf says, "It's going to take a collaborative approach because these are expensive practices and you can't expect a farmer to have the burden of installing these practices all themselves."
Kult adds, "It's not like cover crops where some of that installation cost is going to be recovered in the cover crop and returned to that field the next season. And we're not able to improve soil health with a bioreactor like we would cover crops or a no till program would do. So, yeah, these are all kind of altruistic benefits right now."
In the end, there's no silver bullet to preventing nutrients like nitrogen from leaving the farm. It takes a bunch of different efforts that need to be tailored to specific farms.
One of the scenarios of the Iowa Nutrient Reduction Strategy calls for nearly 100,000 bioreactors in the state.
Hay hopes farmers can expand the number of practices on their fields, "Kind of an ideal situation, we'd be doing all of it. We'd have good in field management, we'd tie in some cover crops, or some perennials in portions of the landscape to tie up some of those nutrients and then have an edge of field practice to catch whatever's left."