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

Aug 2021


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 are soil N 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 goal of this proposal is to improve our understanding of the importance of seedling disease and N dynamics as influenced by cereal rye on corn growth and development.


An intense field trial will be established at an ISU Research Farm in central Iowa and a less intense field trial will be located at the Southeast Research Farm. Both trials will use six N rates under both cereal rye and no cereal rye cover crops. The intense trial will evaluate the N and disease interactions at three landscape positions. The knowledge gained from this research will (i) improve our understanding of cereal rye biomass effect on N dynamics and seedling disease, (ii) decipher the ability to reduce corn yield drag by adjusting N application rates, and (iii) provide farmers with best management practices to ensure a successful corn production following cereal rye cover crop.

Project Updates

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

June 2022

In the spring of 2022, cover crop biomass was collected in mid-April and at the time of termination at both Ames and Crawfordsville. Three sequential in-situ soil mineralization tubes were placed and collected in two-week intervals prior to and following corn planting. Three additional in-situ soil sampling period will occur between V6 and corn maturity. Plant density, plant height and disease seedling samples were collected from both field locations. The Ames location is showing nitrogen application rate differences very nicely.

Other activities included one field day.

January 2022

In the fall of 2021, two research locations were established with the drill seeding of a cereal rye cover crop following soybean harvest. The Ames location is at the Kelley farm and has three landscape positions (summit, slope, toeslope). Soil samples were taken to determine nutrient analysis for fertility applications as well as to characterize the soils. The second location is at the Southeast Research and Demonstration farm (Crawfordsville, IA), which only contains one landscape position.

Other activities included one presentation.