Several Indiana farmers who are comfortable with cover crops are using a roller-crimper to terminate cereal rye cover each spring. The Vermillion County Soil and Water Conservation District purchased a 20-foot-wide roller-crimper for local farmers to use to terminate cover crops. In spring 2020, that roller-crimper ran across about 1,700 acres of cereal rye.

Several lessons learned in 2020 and previous years might help others:

Every year is different. The 2018 season was a difficult year to learn how to roller-crimp in west-central Indiana. Cereal rye tended to break winter dormancy late, and then growth slowed again when it turned dry. There never was that famous growth spurt. Rye was less than 4 feet tall when headed out and the dry weather sent it into a dormant stage, making it difficult to crimp. 

In 2019, the wet spring meant planting was delayed. Cereal rye reached full maturity by planting and was ready to crimp.

For the most part, 2020 was normal and cereal rye matured as it should, meaning it was ready to terminate by mid-May.

Timing is everything. Cereal rye must be at the right stage of maturity to be terminated with a roller-crimper. That may mean running the crimper later than you would like to plant beans.

A rule of thumb: Plant when it’s time to plant; crimp when it’s time to crimp. Those may be two drastically different times. The key is making it work. For complete termination, rye must be mature enough to shed pollen. You may need to consider shorter-season hybrids and varieties to accommodate later planting.

Variety is important. The issue with using “variety not stated” cereal rye is ending up with a mix of several varieties resulting in plants breaking dormancy at different times, growing at different rates and maturing at different times. If you want to use a roller-crimper, you want every plant as close to the same stage of maturity as possible. 

Use a rye variety that will mature around the time you wish to plant. While you’ll pay more for seed, you’ll hopefully improve your chances of complete termination with a roller-crimper.

Rates are important, too. To obtain a mat of cereal rye residue to provide erosion control, conserve moisture, provide weed control and keep the soil surface cooler, you may have to increase your normal seeding rate. This will probably become more vital as microbiology in the soil becomes more active, breaking down residues quicker. Keep bumping up rates the longer you’re in a soil health system.

Soybeans don’t care — to a point. Farmers who crimp are finding a sweet spot for crimping cereal rye after soybean emergence. They recommend waiting until beans are fully emerged. Don’t crimp as soybeans “neck” through the surface.

It’s been said that soybeans could be crimped to the third trifoliate stage. However, this year, some beans were 8 inches tall at the third trifoliate stage. They grew trying to reach the sun when planted green into heavy cereal rye. When crimped at that stage, they were damaged. When crimping over emerged beans, height may be more of a consideration than growth stage. It seems they need to be fewer than 4 inches tall.

Donovan is a district conservationist for the Natural Resources Conservation Service. He writes on behalf of the Indiana Conservation Partnership.