URBANA, Ill. — The Natural Resources Conservation Service, part of the U.S. Department of Agriculture, has awarded $1.12 million to support University of Illinois-led research to clean agricultural drainage water through saturated buffers and denitrifying bioreactors.
The investment, part of NRCS’s Conservation Innovation Grant program, was matched by numerous stakeholder partners in Illinois, Iowa and Minnesota, for a total of nearly $2.25 million.
Dissolved nitrate in Midwestern agricultural drainage water is a major contributing factor in downstream water pollution, including feeding the algae that cause the so-called dead zone in the Gulf of Mexico. Saturated buffers and denitrifying bioreactors are low-cost, passive solutions, but they haven’t been widely adopted across the region.
“The overarching goal of this new project, and for all our university and private partners, is to make bioreactors and saturated buffers work better, and also to increase their adoption across the Midwest,” said Laura Christianson, project director on the grant and assistant professor in the Department of Crop Sciences at the U of I.
Reid Christianson, research assistant professor in crop sciences, and Richard Cooke of the Department of Agricultural and Biological Engineering, are also on the Illinois team.
Actually, it’s not entirely clear how widely the technologies have been adopted, Christianson said. That’s one of the aims of the project: to populate a database of the design and performance details of all bioreactors and saturated buffers across Illinois, Iowa and Minnesota.
Christianson said that information will help researchers understand what’s working and what isn’t, so they know what to improve in future designs.
The project will also trial what Christianson calls “weird” modifications to the usual bioreactor and saturated buffer designs. Bioreactors are large trenches full of wood chips and saturated buffers are riparian areas, often planted with water-loving perennial grasses. In both cases, they’re situated between cultivated fields and drainage ditches.
Generally, tile drains empty into these zones, and bacteria on the wood chips or soil remove the nitrate as water flows through. But water can flow too fast for the bacteria to work, especially in the spring.
“The purpose of the weirdness is to make these practices work better, especially under the highest flow rates. We’re going to try a number of things to try to even out the flow, like pumping water from drainage ditches back into the bioreactor. We’re also going to try to pair a bioreactor and a saturated buffer together. Sometimes water bypasses the bioreactor, so we’re going to route that into a saturated buffer. With all these modifications, we’re just really trying to treat more water,” Christianson said.
The final goal of the project includes two types of novel monitoring systems. In the past, researchers had to travel to sites on a regular…