Can adjustments to nitrogen rates reduce corn yield drag and disease implications following a cereal rye cover crop?

Jul 2023


Cover cropping is a practice that expands the time a living plant is present between harvest and planting of annual crops. Cereal rye is the most prevalent cover crop grown in Iowa because of its winter hardiness as well as its contribution to soil health and water quality. Greater cereal rye biomass increases the benefits received. However, there are tradeoffs associated with greater cereal rye biomass – most importantly for growers is the potential for corn yield drag.

The two most detrimental reasons for a reduction in corn yield following cereal rye include: soil nitrogen dynamics and seedling disease. To encourage the inclusion of cereal rye as a cover crop on the Iowa landscape for scavenging and recycling N, disease suppression and soil health, there is a need to understand the role of both N and disease as contributors to corn yield drag.


The goals of this proposal are to improve our understanding of the importance of seedling disease and N dynamics as influenced by cereal rye on corn growth and development. The knowledge gained from this research will:

  • Improve understanding of cereal rye biomass effect on N dynamics and seedling disease.
  • Decipher the ability to reduce corn yield drag by adjusting N application rates.
  • Provide farmers with best management practices to ensure a successful corn production following cereal rye cover crop.


Researchers will establish an intense field trial at an ISU Research Farm in central Iowa and a less intense field trial at the Southeast Research Farm. Both trials will use six N rates under both cereal rye and no cereal rye cover crops. The trials will evaluate the N and disease interactions at three landscape positions.

Project Updates

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

January 2024

In the fall of 2023, one research location was established with the drill seeding of cereal rye cover crop following soybean harvest. One fall cereal rye biomass sample was collected from all plots to determine the cover crop establishment. The Ames location is at the Kelley farm and has three landscape positions (summit, slope, and toeslope). Grid soil samples were taken to determine the baseline nutrient analysis for fertilizer application at planting and to characterize the soils.