Winter annuals used as a cover crop can prevent erosion and inhibit weed growth. Adding legumes to a winter annual can fix atmospheric nitrogen and attract beneficial insects.
Traditionally, farmers who plant a winter annual, like wheat or rye, plant in early fall or late summer, once the corn is done. Then, come May or June, they take it off.
But there are some farmers who, as soon as the season’s crop is pulled, start planting a cover crop, such as tillage radish, to loosen the soil, or mustard to suppress soil pests. Then, they simply turn the crop over in the spring.
Certain species of cover crop require no tillage and can add nitrogen to the soil (cutting down on fertilizer needs for summer crops).
Why The Change?
It’s no longer only about erosion control over the winter; It’s also about soil health.
If sticking with a winter annual, know that it will come back in the spring, so you’ll still need to fight it, and weeds.
DuPont Pioneer’s article “Managing Winter Cover Crops” encourages using a mix. “Legume cover crops and grass-legume mixtures will have a more positive effect on corn yield than grasses alone,” the article states.
You’ll likely have a much better kill with earlier cover crops, and better weed suppression.
Come spring, that early cover crop is dead.
It may mean growing one field for your cash crop, while cover-cropping another for soil enrichment. Your immediate profit may suffer.
Healthier soil, though, means a more robust crop, so it may pay off in the long run with better yield and/or better crops when selling.
So Which Cover Crop?
Legume cover crops will provide nitrogen. But legume covers can be slow growers and expensive to establish.
Tillage radishes hold nitrogen and alleviate soil compaction. They’re a good option before summer crops like corn or soybean. But they can be do poorly in areas with extended wet periods.
Consider which cover crop species (grasses, legumes, or brassicas) offer the benefits you’re hoping for and the management commitments you’re willing to make. And, of course, consider your local environment.
Cover Crop Selectors
This helpful Cover Crop Selection Tool from Cornell University bases cover crop choice on management goal, planting time, and duration for New York and surrounding states.
For Pennsylvania specifically, find cover crop resources on the Penn State Extension’s Soil Management site.
Lastly, Midwestern farmers can find help choosing a cover crop through the Midwest Cover Crops Council selector tool.
(Note: view spraying resources, such as spray formulas and dribbling nitrogen calibration charts.)