Rethinking Red Clover as a Cover Crop
January 6, 2015
Frost seeding red clover into wheat has become a popular cover crop system in the upper mid-west and rightfully so. It’s cheaper to establish than other cover crop options in wheat, “Tillage” radish for example; its reliable year in and out because success is not dependent on highly variable August rainfall; the system is “Shovel Ready”, establishment and management operations can be piggy backed on current wheat growing practices; it provides more than full year of soil cover, especially in no-till systems; and the nitrogen credit of up to 80 pounds per acre provides the financial payback. This will be especially important in coming years as we face significantly lower commodity prices without accompanying declines in input costs. A recent uptick in the number of downloads of the UW Nutrient and Pest Management Program publication “Frost seeding red clover in winter wheat” (http://ipcm.wisc.edu/download/pubsNM/RedClover_0109.pdf) indicates increased interest in the practice, presumably as growers look for ways to adapt to current market conditions.
Red clover research in Wisconsin and elsewhere in the upper mid-west has focused on developing best management practices to make this cover crop system more reliable including elucidation of the nitrogen credit for the following corn crop, often using in-season diagnostics to aid in adjusting nitrogen application rates. While laudable, these efforts have largely ignored quantifying a major benefit of the system with financial implications: the corn yield increase caused by including clover, the so called positive rotational effect. Finding the exact cause for this yield bump has defied agricultural science but that’s not important in a financial context, it’s real and contributes to the bottom line, another reason for farmers to adopt this practice. A review of the research literature indicates the yield bump is substantial, in the range of 10 -20%, greater than reported for other cover crop systems: http://www.ctic.org/media/CoverCrops/CTIC_04_Cover_Crops_report.pdf
Reanalysis of some Wisconsin data (Janesville, 2010) found a 24 bushel per acre increase for including clover in the rotation, on top of a 55 pound nitrogen credit (Figure 1), a powerful economic tandem, especially when you consider the credit alone paid for the cover crop and the accompanying soil conservation benefits.
Beginning this January, the Michael Fields Agricultural Institute is partnering with the National Wildlife Federation and UW-Extension to measure and document this yield bump and to communicate results with the agricultural community with a goal of strengthening the financial argument for cover crop adoption. This effort will include a combination of analyzing archived research data and the scientific literature as well as field research. Look for results in a variety of the Institutes outreach activities.
Photo Credit: Martin LaBar – Flickr CC