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Serving: IN
roller-crimper in cereal rye cover crop Natural Resources Conservation Service
MECHANICAL OPTION: Terminating a cereal rye cover crop mechanically without herbicides is a viable option, even after planting.

Should you terminate cover crops without herbicides?

A roller-crimper can take down cereal rye.

Several farmers are taking another step toward better soil health by planting into high-biomass covers and using a roller-crimper to terminate the cover. That puts biomass on the soil surface.

For the most part, when and how to terminate mature cereal rye is a decision the farmer makes. As everyone across Indiana is aware, spring 2019 was extremely wet. Farmers were faced with decisions when the wet soil prevented normal early termination of cereal rye. Some farmers decided to try a different tool, the roller-crimper, which is becoming more available across the state.

The primary reason for the interest in roller-crimping cover crops is the ability to terminate certain covers, such as cereal rye, without herbicides. Organic farmers have used roller-crimpers to terminate cover crops for a while, but now non-organic farmers are also finding the benefits.

Once cereal rye has reached full maturity and is dropping pollen, it can be terminated with a pass of a roller-crimper. If complete termination isn’t obtained, a light rate of herbicide will complete the process.

If you’re new to cover crops, you might ask about the advantages of roller-crimping the cover crop down onto the soil surface. Long-term users find many benefits of cover crop residue on the soil surface.

The heavy mat of cereal rye residue prevents sunlight from reaching the soil surface, thereby preventing many weed species from germinating. This mat of residue is very effective in helping control some of the more difficult weeds, such as marestail and waterhemp, since they need sunlight to germinate.

Dry weather insurance

Midsummer in Indiana usually means periods of dry weather, which can lead to crop stress. A heavy mat of terminated cereal rye cover crop will help protect the soil surface, decreasing evaporation of moisture from the soil and keeping more moisture in the soil during dry weather. This little bit of extra moisture may be just enough to keep your crop from being stressed, thereby fending off any loss of yield.

That adage “What is a half-inch of rain worth in July or August?” is true. It may mean the difference in yield between breakeven and making a profit. Protect your soil with a mat of cover crop residue.

A mat of terminated cover crop also protects the soil from excessive temperatures during the hot weeks of summer. Soil temperature can differ 20 to 25 degrees F between protected soil and unprotected soil.

Why does this matter? Plant roots and soil microbiology like relatively constant living conditions, moisture, temperature and soil oxygen levels. Microbiology in the soil especially doesn’t like extremely high temperatures.

That microbiology is the mechanism that converts nutrients into a form for plant roots to take them up. When the soil gets hot, the microbiology either shuts down or moves deeper into cooler soils. No microbiology and no available nutrients in the rooting zone mean a stressed plant and lower yields.

Again, that mat of terminated cover crop may be the difference between breakeven yield and a profit.

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

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