The use of cover crops in Ohio has been an important focus of existing and newly created conservation efforts to improve water quality in both the Lake Erie and Ohio River watersheds. One of the more popular cover crop species is cereal rye. This fact sheet reviews cereal rye characteristics, such as the growth habit of the species, differences between cereal rye and other small grains, ideal growing conditions and tolerance for poor conditions, and how to identify the species and avoid its potential negative consequences. In addition, the general benefits of cover crops and cereal rye in particular will be reviewed, including how the species may interact with soil to build aggregate stability, scavenge excess soil nutrients, reduce excess soil moisture and runoff over the winter months, serve as a weed control method, and return nutrients to the cash crop being subsequently grown. Recommendations and resources for planting and terminating the cover crop, based on different goals for the cover crop and differing management systems, such as no-till, will be examined. Potential benefits and risks of utilizing cereal rye are also important to consider and will be covered.
Introduction
With the benefits of cover crops becoming more widely understood, more farmers are incorporating them into their management systems. One of Ohio’s most popular species of cover crop is cereal rye, Secale cereale, a cool-season annual with the potential to generate tons (up to 10,000 pounds per acre) of biomass in the short window between harvest and planting seasons.
Cereal rye provides many advantages, ranging from soil improvement to weed suppression. It is widely available in Ohio and is grown across the entirety of the United States (Martin et al., 2005). Though it boasts many ecological benefits, perhaps the most important driver to the adoption of this species is its relatively low seed cost.
Description of Cereal Rye
Cereal rye (Figure 1) belongs to the grass family Poaceae, which also includes corn, wheat, and triticale. Cereal rye is a cool-season annual species that is well-adapted to conditions in the United States but grows best in cool, temperate zones like the Midwest, requiring a minimum germination temperature of only 34 degrees Fahrenheit (Roberts et al., 2018). It tolerates temperatures as low as minus 30 F once it is established (Grubinger, 2021). The species has an upright growth habit and can reach heights of 3–6 feet. Because of its ability to grow quickly, cereal rye can produce up to 5 tons of biomass per acre, though it produces closer to 2 tons per acre on average (Grubinger, 2021). This species has broad adaptability, making it ideal for Ohio’s soil textures that range from sand to clay and everywhere in between (Roberts et al., 2018). Compared to other grass-cover crop species, cereal rye is more cold- and drought-tolerant than wheat but less tolerant of hot weather than oats or barley. Cereal rye is taller than wheat, and it tillers less. Rye is better than oats at improving aspects of soil quality, such as increasing aggregate stability and infiltration rates, but provides less soil penetration than sudangrass. The species is relatively shade-tolerant, which helps it establish successfully when planted into a growing cash crop (Ransom et al., 2021).
Growth Characteristics
Because of cereal rye’s quick growth, it is ideal for short growth windows and can thrive after being planted after late fall harvest (Roberts et al., 2018). The biomass competes with weeds by blocking sunlight from reaching the soil, or through allelopathy, where the plant releases chemicals from its roots that prevent the growth of nearby plants, including weeds (Rees et al., 2020). The plant’s allelopathic effects help to control herbicide-resistant weeds, including foxtail, kochia, and marestail, as seen in research at North Dakota State University.
Because rye grows quicker and taller than wheat, it can serve as a windbreak, trapping soil, snow, and rainfall in the field during the winter (Bowman et al., 2012). Cereal rye’s small seed size allows for easy overseeding into many types of crops during the fall. Its ability to overwinter and resume growth in the spring protects the soil between harvest of the cash crop and when it is time to plant again. Cereal rye is versatile in its ability to grow in different soil types. It prefers light soils, such as loams or sands, but also grows in adverse conditions, such as ponded or aluminum-heavy soils that can result from heavy clays or poorly drained areas (Ransom et al., 2021).
Cereal rye’s fibrous root system allows it to easily scavenge leftover soil nitrogen (N), preventing leaching losses over the wet winter months. This benefit and others, including weed control, are strongly tied to the amount of biomass the plant grows, with measurable benefits appearing above the 500 pound per acre level (Ransom et al., 2021). A study conducted in Maryland showed that rye held 60% of the residual N from silt loam soil following an intentionally overfertilized corn crop. A Georgia study showed that rye held 69%–100% of the residual N after a corn crop (Bowman et al., 2012). In Iowa, cereal rye overseeded into soybeans in August capped leaching losses at 5 pounds of N per acre from September to May (Bowman et al., 2012).
After termination, the roots of cereal rye decompose in the soil, adding carbon to the system. The benefits of increased carbon include higher organic matter levels, increased water-holding capacity, better ability to hold onto and provide nutrients in the soil, and increased resilience during times of weather extremes.
Nutrient Cycling
Many cover crops take up nutrients during the fall and winter and then release them back to the cash crop in the spring as they decompose. Cereal rye is well known for this, except for N. Because of the stemmy composition of the mature plant, N is less available for the following cash crop. The carbon-to-nitrogen ratio (C:N) of cereal rye is an important factor for plant decomposition. It is dictated by the maturity of the plant. A C:N ratio of 24:1 is ideal for microbes to break down carbon-rich material, such as plant residue. If the C:N ratio is higher than the ideal ratio (as it is after anthesis), N is required from the soil to fuel microbes breaking down the plant material. This can temporarily decrease available N until the nutrients from the plant tissue are fully broken down and returned to the soil. If the C:N ratio is less than the ideal ratio (as it is when plants are young and succulent), microbes do not have to use soil N and will mineralize N for use by the following cash crop (Barker et al., 2017). This is one reason it is recommended that cereal rye be planted after corn and before soybeans because reduced soil N will not lower the yield in soybeans like it would in corn. To avoid nitrogen drain, consider early termination (before anthesis) of the cereal rye while its tissue is more succulent and the C:N ratio is lower. This minimizes N tie-up and allows more N to remain in the soil for the cash crop at the beginning of the season. Incorporation of plant residue before the plant reaches 18 inches in height could reduce the possibility of N tie-up (Bowman et al., 2012).
Planting
Cereal rye seed appears similar to wheat seed but tends to be thinner and longer, with a more gray-brown color as opposed to wheat’s yellow to gold color (Roberts et al., 2018). For Ohio’s climate, it is recommended to plant cereal rye between July 2 and Nov. 1 to achieve the most reliable establishment. These recommendations pertain to plant survival and do not reflect required planting dates for cost-share programs. NRCS Appendix A shows required seeding dates and rates for most Ohio cost-share programs. Incorporating shorter-season corn hybrids is one way to maintain grain yield and increase the length of the cover crop planting window in the fall (Barker et al., 2017).
It is recommended to plant cereal rye via drill, between ¾ and 1 ½ inches deep, to ensure proper seed-to-soil contact. Planting deeper than 2 inches is not recommended, as cereal rye is sensitive to planting depth (Grubinger, 2021). When planting via broadcast (without incorporation) or aerial seeding, the seeding rate should be increased to ensure adequate stand. Follow recommended rates for establishment (Cochran & Noggle, 2022):
- 40–90 pounds per acre for drilling
- 45–90 pounds per acre for broadcast with shallow incorporation
- 56–112 pounds per acre for broadcast without incorporation or aerial seeding
Cereal rye has an estimated 18,000 seeds per pound (USDA NRCS Plant Materials Program, 2002). One problem that may arise with drilling cereal rye in a no-till system is that the cover crop planting will follow the rows of the previous cash crop. This may not slow surface runoff as efficiently as perpendicular planting (Barker et al., 2017). If overseeding into a maturing cash crop, wait until the crop reaches the dent (R4) stage in corn or the leaf drop (R7) stage in soybean to ensure the canopy begins to open (Ransom et al., 2021). It is important to note that cereal rye planted via broadcast may not germinate unless rain falls after seeding (Ransom et al., 2021).
Interseeding is a practice that is gaining traction in Ohio. This practice plants cover crops into a cash crop, such as corn, around the V4 stage, before the canopy closes. Cereal rye used in this manner germinates and exists in a semi-dormant stage until crop maturity allows adequate sunlight to reach the soil surface. At harvest, the rye is already established and can continue growing, saving the farmer time in the fall. Seeding rates for interseeding are similar to a fall-planted cereal rye rate (Barker et al., 2017).
Purchasing seed from a local dealer may aid in preventing introduction of new weed species to your farm (Ransom et al., 2021). As mentioned before, cereal rye is a very cost-efficient cover crop to establish. Cereal rye varieties are somewhat inefficient at producing seed but still produce more when compared to many other species of cover crops. Generally, cereal rye seed can be purchased for $15–$20 for a 50-pound bag, which equates to $9–$12 per acre at a 30-pound-per-acre seeding rate, or $18–$24 per acre at a 60 lb per acre seeding rate. Many other single-species or multispecies cover crop mixes cost double or triple that amount to establish (Roberts et al., 2018). If planting as part of a cover crop mix, the cereal rye rate should be reduced by at least 50% to avoid it becoming the dominant species (Ransom et al., 2021).
Management Considerations
As a grass species, cereal rye has a robust, fibrous root system. These roots improve many aspects of the soil, including alleviating compaction, improving aggregate stability, and reducing erosion. As the plant’s roots search for nutrients, they grow both laterally and vertically through the soil. This movement slowly breaks up compaction within the soil profile and over time can significantly improve infiltration rates of a field. Because cereal rye replaces the dormant, bare soil with a growing crop during the winter, it provides a food source for many soil biota, including fungi and bacteria, allowing them to remain constant or increase when they would otherwise decline.
Cereal rye improves a soil’s aggregate stability in two main ways:
- It feeds soil microbes that produce glomalin, a biological "glue" that holds soil particles together and improves the aggregate stability of the soil. This improves water infiltration and aeration of the soil when the rye’s roots break down and decompose. Because of cereal rye’s many fibrous roots reaching through the soil, the chances of soil erosion are reduced significantly.
- The aboveground biomass of the plant reduces the impact of raindrops on the soil surface, greatly reducing the potential for erosion (Figure 3).
Another management consideration when selecting a cover crop species is herbicide interaction. It is important to read the herbicide label and determine what, if any, injury potential your selected cover crop species has, as well as how long the residual interval is for that herbicide. One positive characteristic of cereal rye is its tolerance to commonly used corn and soybean herbicides.
Cereal rye does have disadvantages as a cover crop. As reviewed previously, cereal rye has a potential for tying up N in the soil, making the N less available for the cash crop. It is recommended that cereal rye be planted before soybean rather than corn to mitigate the effects of lower available N.
Cereal rye can also be a host for viruses and diseases that affect other grass species, including corn and wheat. It is important to scout the rye for any signs of disease before planting a grass cash crop. For example, cereal rye is susceptible to wheat streak mosaic virus and the wheat curl mite. Though chances are low that infection from cereal rye could spread to a subsequent corn or wheat crop, it is something to consider when planning a crop rotation (Ransom et al., 2021). If cereal rye is used as a forage crop, it has the potential to become infected with fusarium, causing head blight and damaged seed that could contain vomitoxin. Also, cereal rye can over dry the soil or become a weed in the following cash crop if not terminated in a timely manner.
Termination
Termination timing for cereal rye depends on a few factors, including soil moisture and soil type. A balance must be reached—the longer the rye continues to grow, the greater the cover crop benefits but the more difficult it may be to terminate. Different timings and methods are used to terminate cereal rye. These methods depend on the crop following the termination of cereal rye and the grower’s comfort level. Before selecting a termination method, consider the timing, amount of biomass present, and the upcoming weather (Barker et al., 2017). Rye can be terminated before or after anthesis, depending on the comfort level and goals of the producer, as well as the weather. Anthesis begins after the plant receives 14 hours of daylight in the spring. At this point, reproductive growth begins and the C:N ratio begins to rise (Grubinger, 2021).
If planting corn, terminate cereal rye at least 10–14 days prior to planting to avoid any allelopathic issues and to allow for soil warming and drying (Bowman et al., 2012). A few methods can be used to terminate cereal rye, including the use of chemicals, tillage, a roller-crimper, or mowing. Chemical termination can be done either prior to or after planting the cash crop. The most popular and effective methods of termination are tillage, herbicides, or a combination of the two. Keep in mind that tillage can negate many of the benefits of utilizing cover crops and will not be feasible in no-till systems. In these situations, mowing or using a roller-crimper may be adequate to manage the biomass before it can be sprayed with herbicide (Barker et al., 2017).
Planting green, or termination of the cover crop after planting the cash crop, is one practice that is gaining popularity with cover crop growers. In no-till or organic systems, the standing rye offers additional coverage of the soil, allowing the cash crop to germinate and begin growing with less weed pressure. Standing rye prevents sunlight from reaching the soil surface, which is required for weed seed germination. However, planting green can come with its own set of issues, including harboring pest species of insects and disease, competing with the cash crop for water and nutrients, and causing machinery malfunctions due to wrapping of plant material around the planter as it moves through the field. In a dry spring, planting green is not recommended, as large amounts of biomass can dry out the soil and be detrimental to cash crop establishment. However, in a wet spring, it may be beneficial to plant green to allow the cover crop to continue taking up soil moisture. This is one reason it is recommended to plant green only if you have previous experience growing cereal rye as a cover crop (Barker et al., 2017).
Tillage can be effective at terminating cereal rye if the plants are at least 12 inches tall. One issue that may arise if terminating with tillage is clumping of the plant roots with the soil. This requires the use of secondary tillage to prepare the seedbed. This extra tillage is not ideal because it lessens the benefits of using the cover crop in the first place. In addition, incorporation of green residue can attract pests such as seed corn maggot, requiring the use of a soil insecticide or seed treatment (Barker et al., 2017).
If utilizing a roller-crimper, the rye must be at anthesis or later to ensure complete termination (Figure 2). Cereal rye, if left to grow past anthesis, can pose challenges in future growing seasons. The species is prone to seed shattering and can result in unwanted volunteer rye that requires additional management. Because of the seeds’ light weight, it can also be difficult to clean out of equipment, resulting in seed dispersal to other locations (Ransom et al., 2021).
For chemical termination, the use of broad-spectrum herbicides with short residuals is recommended to avoid injuring the cash crop while maintaining effective control of the cover crop. Ensure that the herbicide has effective control of the species you are attempting to terminate (Barker et al., 2017).
Summary
Cereal rye is a popular cover crop species that provides a wide array of benefits to the soil, nearby water quality, and cash crop yield. Rye can improve soil aggregate stability and infiltration rates, thus reducing nutrient and soil loss from the field via erosion. By removing nutrients from the soil and later returning them after decomposition, this cover crop provides a secondary nutrient supply to the following cash crop. Because of the potential for difficulty in terminating this species, it can become a weed for novice growers. In addition, the high C:N ratio of rye can tie up N in the soil, which can potentially cause issues for a following corn crop. With experience, termination and nutrient tie-up risks can be mitigated, allowing farmers to reap the benefits of using this cover crop species.
Resources
- SARE Publication, Managing Cover Crops Profitabl (pp. 98–105)
(sare.org/wp-content/uploads/Managing-Cover-Crops-Profitably.pdf) - USDA Plant Fact Sheet: Cereal Rye
(plants.usda.gov/DocumentLibrary/factsheet/pdf/fs_sece.pdf) - Midwest Cover Crops Council, Cover Crops Field Guide 3rd Edition
(edustore.purdue.edu/id-433.html) - Growing Rye as a Cover Crop in North Dakota
(ag.ndsu.edu/publications/crops/growing-rye-as-a-cover-crop-in-north-dakota) - Cereal Rye as a Cover Crop in Ohio, MCCC-FSOH-3
(midwestcovercrops.org/wp-content/uploads/2023/02/MCCC-FSOH-3-CerealRye.pdf) - Considerations When Planting Green
(cropwatch.unl.edu/2020/considerations-when-planting-green) - Winter Rye: A Reliable Cover Crop
(uvm.edu/vtvegandberry/factsheets/winterrye.html) - Ohio Agronomy Guide, 15th Edition
(stepupsoy.osu.edu/sites/hcs-soy/files/472%20Ohio%20Agronomy%20Guide%2015%20Ed%20red_0.pdf) - Principles of Field Crop Production (pp. 429–439)
(amazon.com/Principles-Field-Crop-Production-4th/dp/0130259675) - Cereal Rye as a Winter Cover Crop, Univ. Arkansas
(uaex.uada.edu/publications/pdf/FSA-2182.pdf) - Midwest Cover Crops Field Guide, Midwest Cover Crops Council
(edustore.purdue.edu/id-433.html)
References
Barker, D. J., Culman, S., Dorrance, A., Fulton, J., Haden, R., Lentz, E., Lindsey, A., Lindsey, L., Loux, M., McCoy, E., Michel, A., Noel, J., Paul, P., Sulc, R. M., Thomison, P., Tilmon, K., & Witter, J. (2017). Ohio agronomy guide (15th ed.). Ohio State University Extension.
stepupsoy.osu.edu/sites/hcs-soy/files/472%20Ohio%20Agronomy%20Guide%2015%20Ed%20red_0.pdf
Bowman, G., Cramer, C., & Shirley, C. (2012). Managing cover crops profitably (Third ed.).Sustainable Agriculture Research and Education (SARE) Program.
sare.org/wp-content/uploads/Managing-Cover-Crops-Profitably.pdf
Cochran, R., & Noggle, S. (2022). Cereal rye as a cover crop in Ohio [Fact sheet]. Ohioline, Ohio State University Extension.
ohioline.osu.edu/factsheet/anr-0114
Grubinger, V. (2021). Winter rye: A reliable cover crop. University of Vermont Extension.
uvm.edu/vtvegandberry/factsheets/winterrye.html
Martin, J., Warren, L. D., Stamp, D., & Waldren, R. (2005). Chapter 16: Rye and triticale. In Principles of field crop production (Fourth ed., pp. 429–439). Pearson Prentice Hall.
amazon.com/Principles-Field-Crop-Production-4th/dp/0130259675
USDA NRCS Plant Materials Program. (2002). Cereal rye, Secale cereale L [Fact sheet]. U.S. Department of Agriculture Natural Resources Conservation Service.
plants.usda.gov/DocumentLibrary/factsheet/pdf/fs_sece.pdf
Ransom, J., Berti, M., Endres, G., Franzen, D., Friskop, A., Ikley, J., Kandel, H., & Ostlie, M. (2021, March). Growing rye as a cover crop in North Dakota. North Dakota State University.
ag.ndsu.edu/publications/crops/growing-rye-as-a-cover-crop-in-north-dakota
Rees, J., Proctor, C., & Koehler-Cole, K. (2020). Considerations when planting green. University of Nebraska-Lincoln CropWatch.
cropwatch.unl.edu/2020/considerations-when-planting-green
Roberts, T., Hoegenauer, K., Ross, J., Norsworthy, J., Barber, T., Robertson, B., Lorenz, G., Faske, T. (2018). Cereal rye as a winter cover crop. University of Arkansas Division of Research and Extension.
uaex.uada.edu/publications/pdf/FSA-2182.pdf