Field Trials to Evaluate N Export from Perennial Groundcover Corn Systems

Aug 2020


Corn and soybean dominate the Midwestern landscape. Both are annuals, only present on the landscape for a fraction of the year. In their absence, they cannot intercept and protect soil from rainfall, nor can they slow runoff and promote infiltration. Members of the research team pioneered a perennial groundcover (PGC) system for corn, wherein a summer-dormant perennial groundcover, such as fescue, provides year-round soil cover. Managed correctly, the corn thrives because the cover is dormant in the summer. The PGC approach requires fewer late and early-season field activities, which are barriers to wider adoption of annual cover crops. Modeling predicts that PGC-corn can reduce runoff, enhance soil organic matter and reduce nitrogen leaching. However, further field research is needed to validate modeling to better understand the impact of a PGC-corn system on nitrogen loss.


This project will provide experimental data that can be used to validate models and to estimate the potential impacts on nitrogen-export of widespread PGC-adoption.  


Researchers will implement PGC-corn treatments at ISU’s Northeast Iowa Research and Demonstration Farm to monitor the surface and drainage water volumes and macronutrient concentrations and compare to long-term controls at the same site.

Award Number: 

Project Updates

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

March 2024

Final Report Pending

June 2023

Field Activities: Cereal rye cover crop samples harvested, ground, and sent for nutrient analysis, May 2023 Kentucky bluegrass replanted, May 2023 Interseeded cover crop planted 6/8/23 Buried three t-shirt strips in each plot for collection at one-month intervals, June 2023 Soil erosion pads placed in all corn plots June 2023 Bi-weekly NDVI measurements taken of perennial groundcover, May – June 2023 Lab Activities: Ongoing aggregate stability measurements with SLAKES app and Cornell Wet Aggregate Ongoing soil moisture analysis for biweekly samples Creation of light box to compare accuracy of PGC density image analysis program Reporting & Presentation Activities: INRC project poster presented at ISU NSF-funded Datafewsion symposium, January 2023 INRC project poster presented at ISU College of Engineering Advisory Board, May 2023 INRC project poster presented at Iowa Pork Congress, January 2023 INRC/RegenPGC presentation for USDA Deputy Undersecretary of Agriculture visit, January 2023 INRC/RegenPGC presentation for student in ISU Graduate Student Emerging Leaders Academy, March 2023 INRC/RegenPGC presentation for 2023 Annual Conference of the Institute of Biological Engineering, April 2023 INRC/RegenPGC oral presentation for Alpha Epsilon Honor Society Induction, April 2023 INRC/RegenPGC presentation for USDA North-Central Region Plant Introduction Station scientists, April 2023 INRC/RegenPGC presentation for Corteva Scientists (ISU Foundation organized event), June 2023.

PGC germination experiment (co-funded by RegenPGC), July 2023 Presentation at ASABE 2023 Annual International Meeting, July 2023 Undergraduate research poster at ASABE 2023 Annual International Meeting comparing aggregate stability methods, July 2023 Soil and Water Conservation Society Poster (co-funded by RegenPGC), August 2023

January 2023

Field and laboratory activities during this reporting period included:

  • Took wide row corn samples and samples of interseeded cover crop harvested
  • Buried three t-shirt strips in each plot and collected in one-month intervals to compare decomposition
  • Collected soil samples for soil moisture content and aggregate stability tests for 10 samples per plot in 2022
  • Dried, ground and analyzed interseeded cover crop samples
  • Transcribed hand-collected meter readings from drainage system
  • Completed aggregate stability tests and soil moisture measurements for 10 samples per plot using SLAKES app Began second method of aggregate stability test for comparison
  • Completed statistical analysis for soil moisture, aggregate stability, water quality and yield in 2022

Other activities:

  • Iowa Learning Farms Webinar: Developing Large-Scale, Reliable Perennial Groundcover Systems - Challenges & Approaches from RegenPGC (09/28/22)
  • Poster presented at Iowa Water Conference
  • Presentation at 2022 ASABE AIM field day on August 24 at NERF
  • Presented results at RegenPGC field day on September 15 at Sorenson

July 2022

Field and laboratory activities during this reporting period included:

  • Cotton strips prepared and buried in 24 fields for biological activity analysis in controls and treatments
  • Biweekly trips to Nashua for soil samples collection and NDVI measurements began early May, 2022 and ongoing through field season
  • Interseeded cover crop planted in 6 plots, June 17, 2022
  • Perennial ground cover sprayed with Liberty (nonselective herbicide for broadleaf and grassy weeds), no longer requiring a hooded sprayer for setback; observed good suppression
  • Spring rye cover crop harvested. Analyzed C, N, and P to be used as part of overall mass balance
  • Conducted late spring soil nitrate sampling on 6/30 
  • Ongoing measurement of soil moisture content and aggregate stability (via 2 methods)
  • Cereal rye cover crop samples processed and submitted for nutrient analysis
  • Water quality sampling and analysis ongoing
  • Ongoing data analysis

Other activities:

  • Field day at ISU Northeast Research Facility (May 23)
  • Presented poster at field day at York, NE (as part of greater RegenPGC project) 

January 2022

During this project period, field activities included:

  • Sampled interseeded cover crop harvested, ground, and sent for nutrient analysis
  • Soil moisture content and aggregate stability tests were completed for 12 samples per plot during 2021 season lab activities:
  • Corn stover samples were harvested, ground and sent for nutrient analysis
  • Transcribed hand-collected meter readings from drainage system
  • Statistical analysis completed for soil moisture, aggregate stability and yield

Reporting and presentation activities:

  • Held a Nov. 11 Field Day at the ISU Northeast Research Farm
  • Completed the annual farm report and gave a project update presentation to INRC
  • Began preparing poster presentation for 2022 Iowa Water Conference and drafting abstract for 2022 ASABE AIM
  • Plans are made to give presentation on cover crops and perennial groundcover approaches at 77 counties in Iowa during February and March 2022.

Other accomplishments:

The team secured a $10 million, 5-year USDA - NIFA Agriculture and Food Research Initiative competitive grant that will involve 18 co-investigators at multiple institutions. The project is entitled "Regenerating America’s Working Landscapes to Enhance Natural Resources and Public Goods through Perennial Groundcover (RegenPGC). This proposal, submitted April 1, 2021 and funded Sept. 15, 2021, is directly related to the activities of this INRC effort.

July 2021

During this reporting period, the project team:

  • Secured a twin-row planter and hooded sprayer to be used on the Interseeded cover crop mix on 30- and 60-inch row corn plots.
  • Conducted soil and water sampling on all 36 1-acre experimental plots throughout growing season
  • Conducted one field day (25 attendees) focusing on perennial groundcover and other conservation practices. Held three other presentations. Found tremendous interest in the PGC systems
  • The team secured additional funding from Iowa Pork Producers Association to expand scope of work related to this project. The IPPA funding will allow soil measurements to include erosion from all 36 plots.

December 2020

Activities during this period:

  • Established perennial groundcover (Kentucky bluegrass) on three plots at Northeast Research Farm.
  • Planted cover crop (cereal rye) on three other plots at NERF 3.
  • Applied manure to 12 plots (3 PGC treatments, 3 cereal rye cover crop treatments, six interseeded cover crop treatments).
  • Conducted preliminary soil sampling for phosphorus and basic soil chemistry on all 12 plots.
  • Recruited graduate student on project.
  • Determined proposed seed mix for interseeding cover crop.