Cereal rye cover crops added to a corn-soybean rotation seem to have little negative effect on yield, according to a five-year study conducted by Iowa Learning Farms and Practical Farmers of Iowa. Ten Iowa farmers have devoted part of their acres to conduct the study.

Between 2009 and 2013, the farmers established side-by-side strips of corn/soybean crops with a winter cereal rye cover crop, and strips using no cover crop, replicated at least two times. 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.

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 so. The properly managed cover crops had little to no negative effect and, in some cases, actually improved soybean yield.

“When I first started the trial, I thought the following crop would suffer because of the competition for water and nutrients,” says Butler County farmer Rick Juchems. “That has been proven wrong with stronger yields and better soil quality.”

Juchems’ corn yields remained steady and he saw a slight improvement in soybean yields on the cover crop acres last year as well as in 2011.

Proper management is a key issue when incorporating cover crops into a corn-soybean rotation. Knowing which cover crop to plant, when and how to plant and terminate the cover crop are the main components to successful management. There are many resources to help farmers with answers to these management details. Primary resources can be a cover crop farmer champion contacted through the ILF or PFI network, or a local Extension field agronomist or NRCS field specialist.

Cover crops provide numerous benefits to farm fields. They reduce erosion by holding soil in place, increase soil microbial activity and nutrient cycling, reduce excess nitrogen and increase soil carbon. The biomass from the plant helps to build soil organic matter as well. Cover crop varieties range from grains like cereal rye, legumes such as hairy vetch, and brassicas including radish and rapeseed. Winter cereal rye was the only cover crop used in this study.

The farmers in this study include: Bill Buman, Harlan; Jim Funcke, Jefferson; 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.

A four-page summary of the study is available online at the ILF website: www.extension.iastate.edu/ilf/content/cover-crop-research, and the PFI website: practicalfarmers.org/farmer-knowledge/research-reports.