Evaluation of Cereal Cover Crops Prior to Corn

Trial Objective

• Cereal rye is a cool-season winter annual that is a good cover crop that is easy to establish, but seed costs and seed availability can be limiting and allelopathic effects may be a concern.
• Wheat seed may be more readily available than cereal rye.
• The effects of cereal rye and wheat as cover crops prior to corn has not been fully explored in Michigan (MI).
• While cover crops, such as cereal rye and wheat, 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 and tillage options were assessed to determine the impacts of a cover crop and tillage on final stand and yield potential of the following corn crop.

Research Site Details

• Cereal rye and wheat cover crops were planted in November 2016 and November 2017 after harvest.
• Cereal rye and wheat cover crops were terminated using Roundup PowerMAX® herbicide at two timings:

— Two weeks prior to planting corn (Pre-plant)

— The day of planting (At-plant)

• A 103-day relative maturity corn product was planted at 35,000 seeds/acre.
• Prior to planting, 5 gallons of 10-34-0 were applied in-furrow and followed with 60 gallons of 28% UAN at the V5 growth stage.
• All treatments were planted on the same day.

— May 9, 2017

— May 18, 2018

• Four cover crop and tillage treatments were compared:

— Cereal rye cover crop, no tillage

— White wheat cover crop, no tillage

— No cover crop, no tillage

— No cover crop, conventional tillage

• The trial was a split plot design with cover crop removal timing as the whole plot and cover crop as the sub-plot. A confidence interval of 95% was used to compare treatment means.

Understanding the Results

• The termination timing of the wheat cover crop had little effect on subsequent corn stands and yield in both 2017 and 2018.
• When averaged over both years, termination of cereal rye two weeks prior to planting had a beneficial impact (though not significant) on corn stand counts and yield (Table 1 and Figure 4).
• Termination of the cereal rye cover crop at the same time as planting may negatively impact yield due to: competition with emerging corn plants for light, delayed availability of nitrogen, and allelopathic compounds suppressing the growth of corn seedlings.

What Does This Mean for Your Farm?

• Modifications of farm operations to include cover crops is a valuable sustainability effort for growers to pursue.
• Waiting too long to terminate a cereal rye cover crop may reduce yield potential.
• Wheat may be a viable cover crop alternative to cereal rye with less concern of allelopathy.