Project ID



Changing the configuration of tile drainage structures to allow subsurface flow through a riparian buffer could offer farmers another option for nitrate removal. This project examined the effects of using tiling and buffers to enhance the denitrification process.

Key Question

Can a portion of tile drainage be reconnected to the shallow groundwater system of riparian buffers and by doing so remove nitrate from the tile water before it enters surface waters?


A literature survey indicated that riparian buffers have a large capacity for nitrate removal via denitrification. But in much of Iowa and the Midwest this removal mechanism is limited by the lack of water flowing through buffers as groundwater by the prevalence of tile drains out letting directly to surface waters. This idea was tested by re-plumbing a tile outlet to route some of the tile water through an existing riparian buffer and measured the amount of water redirected and the fate of the nitrate contained within the water.

Principal Investigator(s)

Dan Jaynes


Tom Isenhart

Year of Grant Completion