Quantifying nitrate processing below grass waterways.

Iowa landscape
Land Management

Title: Evaluating the potential for drainageways at the Kirkwood Community College farm to serve as test sites for innovative grass waterway designs

Location: Kirkwood Community College, Cedar Rapids, IA

Time Period: 2019 - 2021

Research Team: Keith Schilling, and Matthew Streeter

Project Description: In this project we evaluated the subsurface soils and hydrogeology found in two grass waterways complexes in eastern Iowa and assessed the potential for nitrate processing to occur in these lowland drainageways. Using data obtained from a network of 12 shallow wells installed across six different waterways, we found that the waterways contained fine-textured and nutrient rich alluvial soils derived from erosion and deposition of upland loess and till. Strong circumstantial evidence, including a high water table, abundant organic carbon, anaerobic conditions, and an ongoing nitrogen source, suggested that conditions within the waterways were conducive for denitrification to occur. We compared groundwater patterns in the waterways to concurrent monitoring in nearby upland cropped fields and found that NO3-N concentrations in waterway groundwater (3.1 mg/l) were 70% lower compared to groundwater beneath nearby cropped fields (10.5 mg/l). Since most grass waterways are tiled, we envision a new “saturated waterway” design that would allow waterway tiles to reconnect upland groundwater to the organic-rich drainageway deposits for NO3-N reduction.


Funders: Iowa Nutrient Research Center, complimentary funding from the Iowa Pork Producers Association started 9/1/21.

Disclaimer: This is an active research site; please contact Keith Schilling (keith-schilling@uiowa.edu) prior to planning any site visits.