Planting Cereal Rye Ahead of Corn: What to Expect

By Brogan Schanz, Field Program Representative

With the increased adoption of cover crops before corn, many questions arise, especially for first-time users. While cover crop species such as Oats or Wheat are common choices due to their simplicity, there's a growing trend among growers to plant Cereal Rye ahead of corn. In this article, we explore the differences farmers can expect in managing this cover crop and the benefits it can bring to your fields.

Timing is a Key Management Factor

Managing a cover crop like Cereal Rye is very different from others. To be successful, it requires meticulous attention to detail and precise timing. Because Cereal Rye persists through winter, termination is necessary in the spring. Commonly, chemical termination is employed from early April through mid-May. Remember, cover crops do not need to be unreasonably tall to achieve the conservation goals that they are planted for. Those of absurd heights become harder to manage, not to mention they can seed out which introduces an entire host of new problems. It's crucial to have a plan in place and until one is comfortable with managing cover crops to achieve their goals, it is recommended to terminate when they're 2”-6” tall to prevent complications.

Nitrogen Management Considerations

After termination, considerations include adjustments to the nitrogen program and addressing potential challenges. Rye cover crops have been accused of tying up available nitrogen, introducing disease, and potentially having an allopathic effect on corn crops. While these are all true to an extent, with the right practices they can be avoided.

Proper practices, as identified by John E. Sawyer, an Agronomy professor at Iowa State University along with his colleagues, found that rye fixates nitrogen and eventually recycles that nitrogen back into the soil profile through plant matter decomposition, rendering it unavailable for the interim period. Although, the amount of time that nitrogen is unavailable depends heavily upon the soil carbon to nitrogen ratio and the rate of decomposition. (Sawyer, John E, et al.) As a result, most growers find it beneficial to supplement their corn crop in small doses. One option of doing so is to consider adding starter solution to the planter pass. This supports development in the early stages by placing nutrients within the root zone where it is easily accessible to seedlings. This will also ward off the effect of “yellow” corn that is sometimes confused with rye allelopathy.

Another option to consider when supplementing nitrogen rates in a corn crop is adding an in-season side dress pass to your operation. Supporting this decision by utilizing in-season nitrate or tissue sampling is recommended, as it is a great resource when determining how much more nitrogen, if any, is needed. In most cases, the bulk portion of nitrogen inputs remain the same. But maintaining the ability to be flexible with the final portions of your nitrogen applications are key when determining success with rye cover crops as a part of your corn program.

Addressing Allelopathic Effects and Diseases

As mentioned, one of the main concerns with planting a rye cover crop is its allelopathic effects on a corn crop. It also has the potential to transmit seedling diseases. However, you can avoid these risks with proper management techniques. Recent studies from Katja Koehler-Cole and her team from the Department of Agronomy and Horticulture at the University of Nebraska and Sarah M. Kurtz of Iowa State University both cite similar management practices to mitigate:

• Ensure that your planters depth meters are accurate to maintain ideal planting depths of 2”. This will reduce contact with cover crop roots, minimizing the transmission of disease or possible allelopathic effects.

• Be sure to terminate cover crops two weeks in advance of planting, as this allows most allelopathic toxins to dissipate before corn germination.

• Utilize proper treatment on seed going into ground that has rye cover crops. Most seed treatments have modes of action against Fusarium and Pythium, but it is always wise to check with your seed representative.

Paying close attention to these factors and abiding by these general guidelines are some of the easiest and most effective ways to avoid the most common issues that plague first time adopters.

Equipment Considerations

Like all things in farming, each step impacts the other and, in most cases, one must first switch to utilizing no-till or at least reduced tillage practices before implementing cover crops. Row cleaners and additional down force can both be very important. Whether you are planting directly into standing or already terminated rye, there can still be a carpet of vegetation to get through. Ensuring that your planter is adequately set up to handle no-till situations and cover crops is crucial for consistent seed placement and emergence. This plays a huge role in competition amongst individual plants for available nutrients and that ultimately affects yield.

Conclusion: Embrace Overwintering Cover Crops

Adapting to cover crops, particularly Cereal Rye, presents challenges, but when it comes to getting the most out of a cover cropped system, there is no comparison. From the additional nutrient loss reduction and boost in organic matter, to the soil retention, and development of soil structure, the advantages are numerous! With attention to detail and effective management, incorporating cover crops enhances sustainability in your field operations.

If you’re interested in implementing cover crops on your operation, the Soil and Water Outcomes Fund is here to help with financial incentives and agronomic support. Send an email to contactus@theoutcomesfund.com and we’ll get you in touch with your local field program representative.

Brogan Schanz, Field Program Representative

Brogan Schanz works with farmers in Eastern Iowa to implement practical conservation practices into their farming operations. He also provides support to affiliate recruiters. Brogan earned a Bachelor of Science in Forestry and Natural Resource Ecosystem Management from Iowa State University. He previously worked in retail agronomy assisting growers with input selection and ensuring their success in the field. Brogan grew up near Amana, Iowa. He and his family currently live in West Liberty, Iowa where he also helps on the operations side of the family farm.

Sources:

Koehler‐Cole, Katja, et al. “Is Allelopathy from Winter Cover Crops Affecting Row Crops?” Agricultural & Environmental Letters, vol. 5, no. 1, 15 May 2020, https://doi.org/10.1002/ael2.20015.         

Kurtz, Sarah M., et al. “Seedling Disease of Corn Caused by Pythium Increases with Proximity of Rye.” Plant Disease, vol. 105, no. 3, 13 Jan. 2021, pp. 538–541, https://doi.org/10.1094/pdis-06-20-1389-sc. 

Sawyer, John E, et al. “Nitrogen Dynamics with a Rye Cover Crop - Iowa State University.” Iowa State University, 29 Nov. 2017, www.agronext.iastate.edu/soilfertility/info/NitrogenDynamics-RyeCoverCrop_ICM2017.pdf.