two images of rulers in the eart measuring cereal rye growth Keith Glewen, UNL
DATE MATTERS: On April 27, the Elbon cereal rye (left) planted Sept. 22 stands 11 inches tall, while the rye planted Nov. 1 reaches 6 inches.

Planting date, varieties affect spring cover crop growth

While cold tolerance varies by species, both Southern and Northern cover crop varieties can do well in Nebraska.

Reduced spring growth resulting from delayed planting of small-grain cover crops was widespread throughout the western Corn Belt this season.

The photograph above, taken by Nebraska Extension educator Keith Glewen, shows the difference in height and biomass production between plots of Elbon cereal rye planted Sept. 22 and Nov. 1.

Even though the risk of failure increases with later planting dates, establishment costs for many small-grain cover crops are often low enough that successful years — where rye establishes and grows well — often outweigh the years when failure occurs. Briefly, fall growth of cereal rye and triticale cover crops was minimal due to adverse growing conditions that followed delayed planting.

Even with good fall growing conditions, up to a 50% decrease in fall growth can occur for each seven- to 10-day delay in planting after Sept. 1.

Cold tolerance
Small-grain varieties within a species are identified as either spring or winter types. Often spring and winter designations are true only for the region where they were selected and developed, and even then, there may be exceptions. For example, a winter variety developed in the southern U.S., such as Elbon cereal rye, may not survive extended cold and dry winter temperatures common in the central and northern U.S. Also, a winter variety may not survive even where it was developed due to extended periods of extremely cold and dry temperatures.

Nevertheless, most cereal rye cultivars will survive winters in the central and northern Great Plains, regardless of whether they are they classified as a "Northern type" or a "Southern type." Northern-type cereal rye cultivars are very winter-hardy with longer winter-dormant periods than the Southern types. Southern types can have longer growth into the winter and are often the first of the small grains to begin growth the following spring.

Take this to the field
Fall seeding dates greatly affect spring biomass production. Later planting means less biomass. These differences were exaggerated in the fall and winter of 2017 and 2018 because of adverse growing conditions.

Cold tolerance and winter-hardiness vary with species and within species. Both Northern and Southern type cover crop varieties can do well in Nebraska.

Redfearn is a Nebraska Extension forage crop residue specialist, and Elmore is an Extension cropping systems agronomist. This report comes from UNL CropWatch.

TAGS: Cover Crops
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