Oftentimes growers limit themselves to planting only cereal rye after harvesting soybeans or corn. Rye is always a good selection because it will germinate and overwinter, you can plant it any time through the fall, and it will grow next spring. But it is time to think bigger and broader to expand your cover crop benefits.
Winter peas are a great cover crop option, but they come with some challenges. Over the last couple of years, I have heard of issues regarding the establishment of winter peas. They can be difficult to grow in some soil types and field conditions as don’t respond well to poor soils, low fertility or low pH, and they aren’t super winter-hardy either. This lack of winter hardiness discourages growers from planting them.
Austrian winter pea plants typically lose some top growth during cold temperatures and winter freezes, but will continue growing even as temperatures fall as low as 10⁰ to 15⁰ F. Our Soil First management guide lists them with a USDA Hardiness Zone number of 6+, the same as annual ryegrass.
Unlike ryegrass, however, winter peas have shallow tap roots, which limits their ability to withstand cold temperatures. Prolonged exposure to temperatures below 20⁰ F without snow cover terminates most Austrian winter peas. But planting winter peas with a winter cereal grain makes sense as those grasses help protect the young plants and roots.
Research from the University of Nebraska indicates planting winter peas about 3” deep will protect against premature damage from cold temperatures. Some may argue whether planting peas at that depth allows them to emerge when we are seeding cover crops in late summer and fall into less than ideal soil conditions. But remember that the growing point of winter peas, like soybeans, is at the top of the plant and exposure to cold temperatures early will terminate the plant before it has any chance to grow and produce biomass. Newer varieties do show promise when it comes to cold tolerance, but seed companies still have more work to do on this.
On the other hand, it’s safe to say that planting winter peas is more cut and dried than other cover crop species, too. Because of their size, aerial applications aren’t recommended. And in in many cases where they are broadcast on top of the soil and lightly incorporated, we don’t see good emergence. That leaves ground equipment like air seeders, drills and row crop planters as the best approach, which is helpful when striving to control seeding depth.
The time and method of planting cover crops is CRITICAL to their success. The industry is learning more and more all the time, and while planting rye anytime or anyway seems to work, other species aren’t so cooperative. Winter peas are a perfect example of a right way and a wrong way to get things done. Too often, practices don’t match up with the species being seeded and that keeps more growers from adopting the practice. For more information on seeding and managing winter peas and other cover crops, go to soil1st.com/.
CCA Scott Wohltman is the cover crop lead at La Crosse Seed. He focuses on educating the agricultural communities of the Midwest on the importance and benefits of cover crops.