One of my pet peeves is when someone calls a cover crop “annual rye.” There is no such thing as annual rye. When you are planting cover crops, you either plant cereal rye or you plant annual ryegrass, not annual rye.  

Cereal rye and annual ryegrass are not the same kind of plant. They require different management techniques and can have different challenges. 

There are differences

Cereal rye is a cereal grain, like barley, wheat and corn. Annual ryegrass is a grass, like orchardgrass and fescue. Although they appear to be similar, they are not related and have many different characteristics.

Do you ever wonder why annual ryegrass might be a challenge to terminate? That is because it develops roots up to 60 inches deep over the winter, requiring you to kill the plant all the way to the bottom to fully terminate the plant and prevent regrowth.

Terminating annual ryegrass with a roller crimper is not an option; you must use tillage or chemical termination. The carbon-to-nitrogen ratio will be much less in annual ryegrass than mature cereal rye, so ryegrass residue may not last through the summer, as it will break down quicker.  

Annual ryegrass can make some excellent spring forage for either grazing or mechanical harvesting, and it also can provide some cover crop benefit as it regrows. It can tolerate wet conditions, making it a primary species for floodplain fields. The roots penetrate compacted layers while also tolerating acidic layers. Annual ryegrass also must be planted earlier than cereal rye — usually by the middle of October throughout much of the state. 

Cereal rye characteristics

Planted in the fall like wheat, cereal rye can go from a 10-inch cover to a 6-foot-tall jungle in a matter of days during a wet spring. That is not a major problem if you are planting soybeans, but it can be if you are planting corn.  

Once you terminate cereal rye, microbiology starts breaking down residue. To do so, it needs available nitrogen, and your newly planted corn crop also needs nitrogen. Remember, bugs eat first, so your corn may not be getting the nitrogen it needs. Corn going into mature cereal rye needs all the starter N you can put on with the planter.  

Do not ever terminate mature rye ahead of planting if there is any chance of rain. If the rye develops a mat on the soil surface, the soil will not dry out so you can plant. Plant, then terminate. Cereal rye can be terminated with a roller crimper. To fully terminate, the cereal rye must be mature and dropping pollen. 

If you are considering using either annual ryegrass or cereal rye, do your research and use them effectively. One option is to use cereal rye after corn ahead of soybeans and use annual ryegrass after soybeans ahead of corn.

Test any cover crop on a small acreage before replicating across your entire farm. Ask questions. Use strip trials. Do your research so you can reach a comfort level.