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Rye: There Seems to be Some Confusion

Rye, ryegrass, winter rye and cereal rye - all the same thing or not? I often hear growers talk about ryegrass when I suspect they really mean cereal rye. Rye, winter rye and cereal rye all refer to the same thing - cereal rye (Secale cereale) that is an overwintering cereal grain. Ryegrass refers to annual or perennial ryegrass; a very different beast. Lets take a look at the differences.

• Rye grows very aggressively. At heading, rye can have 120 to 150 cm of top growth. The root system is fibrous and extensive, scavenging for water and nutrients through the soil 1m horizontally and as much as 2 m in depth at maturity. Rye grown as a cover crop does not have roots to this degree.
  
• Rye germinates at 1 to 2 C but vegetative growth requires 4 C, this helps to explain the sometimes amazing growth of rye late in the fall. Rye growth in the fall will not be as great as an oat cover crop; rye similar to wheat requires vernalization for further growth and heading.
  
• Rye does not winter kill, which means that the soil surface is protected throughout the winter by live plant material but it does mean that spraying or extensive tillage is required in the spring.
  
• Nitrogen will start to be released for succeeding crops about two weeks after a rye cover crop has been killed provided there are suitable conditions for organic matter breakdown and the rye was not mature or in head when killed. The carbon to nitrogen ratio of the rye residue plays a role in nitrogen release to succeeding crop.

In contrast, ryegrass seems slower to germinate and grow, it remains wispy for a long time. This is the grass that is in most lawn grass mixtures. It is a much finer seed than cereal rye. Perennial ryegrass once established is aggressive and will come to dominate orchard or lawn mixtures if present in amounts greater than 50%. Annual ryegrass (Lolium multiflorum) is that shiny, green grass common in less expensive lawn mixtures. It is a biennial under most Ontario conditions and will attempt to set seed in the second year. Ryegrass has a lovely fibrous root system that with time will create a dense sod. It does a good job of capturing leftover nitrogen but appears to be slightly slower in releasing the nitrogen to succeeding crops. It often has a role in more permanent covers like orchard floor cover where the fibrous root system helps to cushion the soil against harvest damage.

So rye or ryegrass - both are in the grass family but very different in their growth habit and use as cover crops. Make sure you get the one that you really want!

Early spring ryegrass growth - although slow to get going ryegrass makes a dense
sod with its extensive fibrous root system