Research HighlightsOptimizing No-Till Soybean Planted into a Cereal Rye Cover Crop
In this article, you’ll find details on:
- Nitrogen application increased cereal rye biomass but did not affect soybean seed yield
- Delaying cereal rye termination two weeks after soybean planting reduced seed yield
- Plant longer maturity group varieties (>2.0) if terminating cereal rye close to soybean planting
- The seed and soil applied biologicals/stimulants tested did not increase soybean seed yield when planted green
By Mark Kendall, Spyros Mourtzinis, John Gaska, Adam Roth, and Shawn Conley
Dept. of Plant and Agroecosystem Sciences
University of Wisconsin, Madison
Reprinted with permission from CoolBean.info, January 2025
Acreage of soybean planted into a cereal rye cover crop has continued to increase citing benefits including reduced soil erosion and weed pressure in addition to monetary programs available to producers implementing cover crops. This research project’s goal is to take a holistic view of soybean planted into a cereal rye cover crop by testing the effects of various treatments on soybean seed yield and cover crop biomass.
Trial #1
The objective of this research is to evaluate multiple cereal rye termination timings and nitrogen rates on no-till soybean seed yield and cereal rye biomass accumulation in a corn-soybean rotation.
The research team conducted three experiments in southern Wisconsin to evaluate the effects of three different cereal rye termination timings with glyphosate and five different nitrogen rates on soybean seed yield and cereal rye biomass accumulation. The previous crop for two experiments was corn harvested as grain, located at Arlington and Mineral Point. The third experiment at Arlington followed corn harvested as silage. Cereal rye termination treatments for the corn silage experiment were two weeks prior to soybean planting (PP), at planting (ATP), and two weeks after planting (POST), and the treatments for the corn grain experiments were no rye, ATP, and POST (Table 1).
Figure 2 (right). Cereal rye biomass (pooled across termination treatments) comparison among nitrogen (N) rates at Arlington and Mineral Point combined following corn grain. Bars with the same letter were not significantly different (alpha=0.05).
In the corn silage-soybean rotation, the interaction of termination treatments and nitrogen rates increased cereal rye biomass (Figure 1). There was not an interaction in the corn grain-soybean rotation; however, main effects of nitrogen rates (Figure 2) and termination treatments (Figure 4) increased cereal rye biomass. Combining management practices such as delayed cereal rye termination with low rates of nitrogen (25 lb/ac) appears to be a promising strategy to produce greater cereal rye biomass to reduce erosion and suppress weeds.
Figure 4 (right). Soybean seed yield and cereal rye biomass (pooled across nitrogen rates) comparison among cereal rye termination treatments at Arlington and Mineral Point combined following corn grain. Bars with the same letter were not significantly different (alpha=0.05).
Nitrogen fertilizer did not affect soybean seed yield in any experiment. In the corn silage-soybean rotation, soybean seed yield was reduced when cereal termination occurred ATP (~5 bu/ac) or POST (~12 bu/ac) compared to PP termination (Figure 3). In the corn grain-soybean rotation, no rye and ATP termination produced the same soybean seed yield, while POST termination reduced yield by 7 bu/ac (Figure 4). Typically, delaying cereal rye termination does not reduce soybean seed yield; however, seed yield may have been reduced in 2024 due to extended dry weather in August (Reed et al., 2019). Additionally, these fields had no history of cover crops. Previous research found that lower soybean yield can occur in the first year of cover crop implementation; conversely, soybean yield reductions were not found in future study years when there was a history of cover crop usage (Pinnamaneni et al., 2022).
Trial #2
The objective of this research is to evaluate the effect of soybean variety maturity group at different cereal rye termination timings on no-till soybean seed yield.
One experiment was conducted in southern Wisconsin near Arlington. Cereal rye was planted on September 30, 2023, following corn silage harvest. Termination of cereal rye with glyphosate occurred at three timings: 14 days before soybean planting, at planting, and 14 days after planting. Soybean planting occurred on May 6, 2024. Soybean variety maturity groups (N=14) between 0.5 and 3.0 were tested in this experiment. Maximum soybean seed yield was obtained when cereal rye was terminated prior to soybean planting using maturity groups 1.6 and longer (Figure 5). Maximum soybean seed yield could be achieved when cereal rye was terminated at soybean planting or up to 5 days after planting, but longer maturity groups (>2.0) were needed.
Trial #3
The objective of this research is to evaluate the effect of biologicals and/or stimulants on no-till soybean seed yield when planting green into living cereal rye.
Many biologicals and/or stimulants are available to soybean growers, but their utility in soybean-cover crop systems has not been widely tested. Two experiments were conducted in southern Wisconsin near Arlington with previous crops of corn for silage and corn for grain. Cereal rye was planted on September 30, 2023, following corn silage harvest and on October 23, 2023, following corn grain harvest. Soybean planting occurred on April 23, 2024, and eight biologicals and/or stimulants were applied as either a soybean seed treatment or in-furrow at planting. Termination of cereal rye with glyphosate occurred on May 8, 2024.
No differences in soybean seed yield between the non-treated control (NTC) and the biologicals and/or stimulants were measured in either experiment (alpha=0.05).
These are preliminary results as the data were for one year only. All trials will be repeated in 2025 and 2026. Funding for this project was provided by the Wisconsin Soybean Marketing Board.
References
Pinnamaneni, S. R., Molin, W. T. h. o., Anapalli, S. S., Molin, W., & Reddy, K. N. (2022). Effect of Rye cover crop on weed control, soybean (Glycine max L.) yield and profitability. Frontiers in Agronomy. https://doi.org/10.3389/fagro.2022.907507
Reed, H. K., Karsten, H. D., Curran, W. S., Tooker, J. F., & Duiker, S. W. (2019). Planting Green Effects on Corn and Soybean Production. Agronomy Journal, 111, 2314-2325. https://doi.org/10.2134/agronj2018.11.0711
Optimizing No-Till Soybean Planted Into a Cereal Rye Cover Crop – CoolBean fact sheet
Published: Mar 10, 2025
