Iowa Learning Farms and Practical Farmers of Iowa (PFI) recently published the ten-year results of an on-farm field research study about cover crops. And ILF recently released the cover crop statistics it has been tracking for many years. The results of both these newsworthy items include both promise and troubling points. The cover crop study indicates no loss of yield, and limited improvements – not a homerun, but not a strike-out either. The cover crop report shows 880,000 acres in 2018. More than 2017, but a significant slowing of acres planted in cover crops statewide – for the second year in a row.
Farmers and researchers seem to hold the strongest opinions about cover crops – and these opinions are not always the same. Since 2008, before anyone was really talking about cover crops, ILF and PFI launched a long-term on-farm field research study to help understand the impacts of planting cover crops on soil health, yields and nutrient/soil leaching.
As the ILF project lead, I get to work with the farmer partners as well as colleagues at PFI. Stefan Gailans, PFI project lead, noted that research studies such as this are often in response to requests and questions from working farmers looking to improve or change how they operate. A goal of this project is to address the question, “How does a cereal rye cover crop affect cash crop yields?”
To our knowledge, this is the only study in the Midwest that has spanned 10 years of working with farmers on their farms. One challenge for this kind of study is that these farms are run by real people making real-life decisions every day and every year. Operating a farm business sometimes leads to actions and decisions that are not what the researchers would prefer, but sometimes lead to learning by all parties.
Working with farmer-partners in conducting research at field scale, lends weight to the outcomes reported. Farm operators do read studies and look for anything that will give them a performance edge. But, many also like to share tips and tricks with each other, and experiment on their own.
These farmer-partners are not content to only participate in the research project, they have also become strong leaders on cover crop implementation, traveling all over the state to talk at field days and conferences, as well as hosting field days. This is indicative of the trust farmers have in peers, and the broad-based desire to share knowledge and learn from each other. We are always seeking participants and sites for field days to promote conservation techniques such as cover crops. Please reach out to ILF if you are interested in learning more or hosting.
The group of cooperating farmers has varied over the study term, comprising 12 operating farms in Iowa. Taken as a whole, the data collected covers 68 site-years with cereal rye cover crops planted before both corn and soybean cash crops.
The number one negative perception we hear: Cover crops reduce yield.
Cooperators have reported that in 61 of 68 site-years properly managed cover crops had little to no negative effects on corn and soybean yield, and there were improvements in soybean yield in eight site-years and corn yield in three site-years.
While we don’t claim huge yield gains, it’s becoming quite clear that when done consistently and managed well, cover crops don’t substantially impact yields. And there are substantial benefits beyond yield that help to offset the upfront investment in cover crops.
So where do we find the financial upside?
We cannot argue with the logic that cover crops take investment to plant in the fall, and terminate in the spring, however reaching the no yield impact determination allows us to start at zero instead of in-the-hole when assessing return on investment.
Farmers with an inherent values-based desire to improve water quality and conserve soil naturally consider cover crops as a long-term investment in the environment that will bear fruit in many ways. This isn’t saying that they aren’t concerned with the operational costs, just that they tend to roll it into the overall cost of doing business.
For those that are more focused on the exact economic impacts, we suggest a longer-term viewpoint. Soil erosion may take years, but with the loss of each fraction of an inch from the fertile topsoil, the production capacity of a field will go down.
For more detailed information on the project, see “Winter Cereal Rye Cover Crop Effect on Cash Crop Yield” on our website.