Cereal rye cover crops added to a corn-soybean rotation have little to no negative effect on yield and actually increased soybean yields in seven site-years and corn yield in two-sites years, according to an eight-year study conducted by the Iowa Learning Farms and Practical Farmers of Iowa.
In 2008 and 2009, 12 farmers across Iowa established replicated strips of winter cereal rye cover crop and strips with no cover crop within their corn and soybean rotation. The cover crop was either drilled after harvest or aerially seeded into standing crops each fall. At each site, the cover crop was terminated the following spring by herbicide one to two weeks before planting.
When the project began, the farmers were concerned that the winter cereal rye would impact their corn or soybean yields negatively. But after harvest was completed each year, the farmers reported that this was not the case.
When properly managed, cover crops had little to no negative effect and, in some cases, actually improved yields.
"Over the past eight years, my initial concerns have been proven wrong with stronger yields and better soil quality," said Butler County farmer Rick Juchems of his experiences in the project. "A new benefit I’m now seeing is the suppression of weeds, especially ahead of soybeans when the rye is terminated later in the spring."
Juchems’ corn yields have remained steady and he has seen a slight improvement in soybean yields.
Proper management is key when incorporating cover crops into a corn-soybean rotation. Knowing what cover crop to use, when to plant and how and when to terminate are the main components to successful implementation. Effective termination with herbicide requires an actively growing plant. Planter settings also may need to be adjusted to handle increased residue.
There are many resources to help farmers with answers to these management details online and in print, as well as contacting a local cover crop farmer through the ILF or PFI network, an Iowa State University Extension and Outreach field agronomist or NRCS field specialist.
Cover crops provide numerous benefits to farm fields.
They reduce erosion by holding soil in place and improve soil health through increased soil microbial activity, nutrient cycling and soil organic matter. The biomass from the plant can add value through grazing or forage and potentially suppress winter annual and early season weeds.
The farmers in this study include: Bill Buman, Harlan; Randy Caviness, Greenfield; Jim Funcke, Jefferson; Devan Green, Conrad; Rick Juchems, Plainfield; Whiterock Conservancy, Coon Rapids; Mark Pokorny, Clutier; George Schaefer, Kalona; Jerry Sindt, Holstein; Rob Stout, West Chester; Gary and Dave Nelson, Fort Dodge; and Kelly Tobin, New Market.
The year eight update for this study is available online at the ILF website: https://www.iowalearningfarms.org/content/cover-crop-research.
Queck-Matzie is a freelance writer in Fontanelle.
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