Quantifying nutrient load reduction practices and export at field and landscape scales

Jul 2023


The Iowa Geological Survey (IGS) will conduct several concurrent projects during the 2023-2024 reporting period focused on quantifying nutrient load reduction practices and nutrient export at field and landscape scales across Iowa.


Overall, the concurrent field and desktop projects conducted by IGS researchers aim to advance efforts to better quantify nutrient reductions at field and landscape scales across Iowa.


  1. A new saturated waterway practice will be designed, installed and monitored at a farm site in eastern Iowa.
    1. A new grass waterway tile system will be installed to direct a portion of drainage water into drainageway sediments for nitrate load reduction.
    2. At two other field sites in eastern Iowa, IGS will characterize pre-BMP conditions and monitor new saturated buffer installations. At one site, monitoring will focus on quantifying multiple systems installed along a single stream reach. At the other site, monitoring will be conducted to assess installation of a saturated buffer downgradient of surface inlets.
  2. Along with field projects, IGS will conduct desktop analyses on two aspects of nutrient export occurring at the Iowa landscape scale.
    1. In one study, IGS will quantify the speciation of N (nitrate, organic nitrogen, and ammonium) and P (particulate phosphorus and orthophosphate) loads at approximately 60 locations within the state’s ambient monitoring network. Spatial and temporal patterns of nutrient speciation will be evaluated.
    2. In a second desktop study, IGS will quantify the impact of Iowa’s large flood-control reservoirs (Red Rock, Saylorville, and Coralville) on riverine N and P loads. Mass balance results will be used to evaluate opportunities to increase nutrient loss occurring in large reservoirs.
  3. In addition to IGS-led field projects, IGS scientists will provide geological services to other INRC-supported research as requested, including for monitoring well installations, geophysics and groundwater monitoring.

Project Updates

Note: Project reports published on the INRC website are often revised from researchers' original reports to increase consistency.

December 2023

As part of the larger overall project, there were several project elements: Project 1: Installation and monitoring of a new saturated waterway conservation practice Activities: Pre-BMP monitoring wells were installed in 2023 and water samples from wells and drainage tiles were collected every two weeks through the 2023 monitoring period. In the fall of 2023, IGS personal coordinated with the landowner, tile contractor, Agri-Drain, and Iowa State collaborators on a final design and layout. On December 5-6, the new grass waterway drainage system was installed at the site near Reinbeck, IA. A monitoring well network comprising 15 wells was also installed at this time. On December 13, the flow sensor systems were installed in the Agri-Drain boxes. Project 2: Characterization and monitoring of two new saturated buffer sites in eastern Iowa Activities: Electromagnetic (EM) surveys were conducted at the Fawcett and Paustian farms to delineate spatial soil and shallow geologic conditions. At the Fawcett Farm, six monitoring wells were installed and the six wells and upstream-downstream stream were sampled every two weeks from July to December for nitrate and field parameters. We are waiting for the IDALS/NRCS to install the saturated buffer at the Paustian farm that is anticipated for spring 2024. Project 3: Quantifying N and P loads at various spatial and temporal scales Activities: In the first half of the project year (fall 2023) we analyzed the speciation of nutrient loads within Iowa, specifically, the percentage of Iowa’s total P loads that are particulate phosphorus and orthophosphate and the percentage of Iowa’s total N loads that are nitrate, organic nitrogen, and ammonia at 60 ambient monitoring sites. A research paper was prepared and submitted to the Journal of Soil and Water Conservation. Elliot Anderson presented on the topic at the INRC seminar series. The second topic focused on quantifying the impacts of reservoirs on nutrient loads will be the focus in the spring 2024 period. Data for this project has been assembled in a database. Project 4: Provide groundwater monitoring and geological services for Iowa State INRC projects and related nutrient related studies Activities: Monitoring wells were installed for other projects as part of this project. Four wells were installed for Dr. Antonio Arenas for a tile drainage study in Walnut Creek watershed south of Ames. Six monitoring wells were installed for Dr. Billy Beck for a study of the Iowa River floodplain near Belle Plaines. Pressure transducers were installed at the wells sites at the request of the project PIs.

Project Activities:

1 Presentation.


Draft publication submitted to Journal of Soil and Water Conservation: "The Speciation of Iowa’s Nutrient Loads and the Implications for Midwestern Nutrient Reduction Strategies"

BMP Field Work