“Which is better? Winter wheat or cereal rye?” asked Kate Brown of Rutgers Cooperative Extension at a Northeast Cover Crops Council meeting. “I often see this come up in cover crop forums – people asking for the end-all-be-all answer – and I think there’s a lot at play.”

Cereal rye and winter wheat have much in common. They are both winter annual grasses with a similar seed size and a similar growth habit that are planted in autumn. (Do not confuse cereal rye with annual ryegrass.) Cereal rye, however, has a longer planting window because it can germinate in soil temperatures as low as 34º. Of the two species, cereal rye performs better in low fertility and/or acidic soils.

In terms of overwintering and the establishment of a crop, cereal rye is the most cold-hardy cereal grain. It can continue to grow at a minimum temperature of 38º, so it’s easier to accumulate biomass from these species in autumn and winter (depending on location).

About cereal rye, Brown said, “When spring comes and we get green-up and these plants start to actively grow again, because cereal rye can grow at a lower base temperature, we see that it starts to grow earlier in the spring and ultimately mature earlier as well.”

This can be beneficial in certain cropping systems in which a grower is trying to plant directly into mature residue.

Cereal rye can also be beneficial in spring because its vigorous growth can pull excessive moisture from the soil into the plants, creating better planting conditions.

A further benefit of cereal rye is weed control due to its high levels of biomass. Brown cited an example of a farm in New Jersey that roller crimped a stand of cereal rye and then planted pumpkins into the mat. She said that you could not see light through the mat even into late autumn when the pumpkins were ready for harvest.

“So, this species has a very persistent residue and can do excellent things for weed control or, in this case, also keeping soil off of the pumpkins and helping with disease control,” Brown said.

It’s easy to see why cereal rye is the most popular autumn cover crop option. There are, though, some disadvantages that come with this robust crop that can reach heights of six feet at maturity that might cause growers to opt for winter wheat.

Winter wheat produces less biomass at maturity – 2,000 to 8,000 lbs. dry matter/acre versus 10,000 lbs. dry matter/acre for cereal rye. At maturity, winter wheat is also shorter (two to four feet).

The vigor of rye can become problematic in spring because it’s easy to end up with an excessive amount of biomass that is difficult to control. Brown shared anecdotal information of growers who were unable to terminate their cereal rye due to heavy spring rains, and it ultimately led to planting issues.

Left unterminated, cereal rye can begin to produce viable seed. Without tools to manage the volunteer rye (or feral rye, as Brown said it is sometimes called), it can become a nuisance in a cropping system. Additionally, at maturity, cereal rye has a high carbon-to-nitrogen ratio. The result is that it can tie up nitrogen in the soil which is of particular concern for a spring-planted corn crop.

And with cereal rye, there is the consideration of its allelopathic effects – the release of chemicals by one plant (the rye) that inhibits the growth of adjacent plants, which can contribute to weed control efficacy and have negative impacts on the crop being grown.

According to Brown, allelochemicals in rye can inhibit germination or stunt growth of a crop, but this is less impactful with larger seeded crops such as corn.

There are distinct advantages and disadvantages to both cereal rye and winter wheat and ultimately the choice depends on a grower’s goals, such as forage harvest value, the ability to penetrate a plow pan, nitrogen fixation, improving soil organic matter, etc.

Brown awarded cereal rye the “most likely to succeed” superlative and winter wheat the “best team player” superlative.

“Cereal rye is a workhorse with greater adaptability and biomass production than winter wheat – best where focus is on nutrient scavenging, erosion prevention, weed suppression and building soil organic matter. Winter wheat is less competitive in a mix, has a longer spring management window and produces less biomass – a good choice when concerned about termination timing and managing biomass,” Brown said.

She referred growers to the Northeast Cover Crop Council’s tool, the Cover Crop Selector (covercrop-selector.org), which provides cover crop suggestions based on location and grower goals.

The data in the selector tool represent the collective knowledge and experience of cover crop experts in the Northeast. Experts, grouped by their USDA hardiness zone, evaluated each cover crop property in the dataset via deliberative discussions in over 70 teleconferences.