Influence of the Timing of Cereal Rye Cover Crop Termination on Corn Yield

Trial Objective

  • Cereal rye has become a common crop to use in Midwest cropping systems; however, while cover crops can reduce erosion, utilize excess soil nutrients, and increase soil organic matter, they must be terminated in a timely manner in the spring to avoid negatively impacting the following cash crop.
  • In this trial, different termination timings with a burndown herbicide application were assessed to provide information to farmers on the most effective termination time to maximize the yield potential of the following corn crop.

Research Site Details

  • The cereal rye was terminated using Roundup PowerMAX® herbicide with ammonium sulfate at four different dates: April 27th (26 days prior to planting), May 8th (15 days prior to planting), May 23rd (at planting), and May 30th (7 days post planting).
  • Prior to planting 200 lb/acre of nitrogen in the form of 32% urea and ammonium nitrate (UAN) (32-0-0) was applied.
  • Two replications of each treatment were used.

Understanding the Results


  • A factor that may have reduced the rate of decompositon of the cereal rye in 2018 was the colder than average temperatures in the early spring. With the slower rate of decompostion, nitrogen availbility may have been limited during the early growth period of the corn crop.
  • Corn yield decreased with later termination dates (Figure 1).


What Does This Mean for Your Farm?

  • This trial conducted this year showed termination made in a timely manner had a beneficial impact on corn crop yield.
  • Waiting too long to terminate a cover crop may reduce yield potential due to nitrogen tie up.
  • Termination of a cereal rye cover crop close to planting may negatively impact yield due to competition with the emerging corn plants.
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