Managing Over-Wintered Rye Cover Crop in Spring

Winter Rye (Secale cereale) is a commonly used cover crop in backyard grower, community garden and urban farming operations.  It is cold hardy and can germinate in as low as 34 degree soil temperatures making it useful to plant after a fall harvest of summer vegetables that last until the frost date.  Once established it can tolerate sub-zero temperatures over the winter to start rapid growth in the spring.

Winter Rye does many things well:

• Seed is inexpensive and easy to obtain
• Establishes quickly and easily
• Suppresses weeds
• Prevents erosion
• Can create large amounts of organic matter
• Assists in suppressing pests
• Scavenges nitrogen

Winter rye however can present a management challenge as it can regrow depending on what stage of growth it is terminated in and how large it is allowed to get before management methods are implemented.

There are several  different types of management methods that can be used to terminate winter rye.  Each has its place depending on what the need is for the cover crop, what management tools are available,  as well as what is the production plan after the crop has been terminated.  Management Methods:

• Herbicide
• Tillage
• Rolling/Crimping

Herbicides can be used to effectively terminate rye at any stage of growth.  Tillage can have spotty success due to regrowth of clumps if the rye is less than 12 inches tall, and multiple passes may be needed.  Rolling or Crimping is more effective if the rye has gotten about 4 feet tall.  Keep in mind that rye at that stage is very large with woody stems and may be difficult to manage unless the producer has heavy duty equipment.

Rye regrowth after tillage. The rye was tilled 14 days prior at 10 inches tall then followed by rainfall which facilitated regrowth. Will need additional tillage or herbicide application

Rye was terminated in early April at 18 inches tall with herbicide (glyphosate) then compost was added prior to summer vegetables in May

Rye was crimped at four feet tall to terminate growth and left in place, then tomatoes were planted through the rye mulch

Each method of rye termination has benefits and concerns.  A careful consideration needs to be made about what benefits are needed and how that will impact production.  A few things to keep in mind when planning around spring management of winter rye cover crop:

• Rye suppresses germination of seed after termination due to allelopathy.  It can take up to 3 or 4 weeks for that effect to subside.  Make sure to plan termination if early spring seeding is planned.  Incorporating the residue after termination can speed up breakdown of the rye to allow earlier seeding.
• The smaller and younger the rye, the more Nitrogen is present.  Older rye with more stems has more Carbon present.  A ration of 25:1 (roughly the same as well made compost) strikes a good balance of preventing nitrogen loss and preventing nitrogen tie up to break down the rye. (Nitrogen Release from Cover Crops – SARE)  While this can be difficult to accurately predict or measure in rye, it occurs when the rye is starting stem elongation but before it gets to the boot stage. (Purdue – Small Grain Growth Stages)
• The taller the rye gets, the more difficult it gets to manage.  Large scale equipment may be needed. Herbicides such as glyphosate may be less effective the taller the rye gets.

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Cereal Rye for Cover Cropping in Organic Farming – eXtension