Grazing cover crops
Cover crops have traditionally been used to help hold the soil when transitioning between different types of cash crops and are often plowed under before planting the next crop to add organic material and fertility to the soil.
Farmers with livestock often select cover crops that can be grazed, adding an additional benefit in feed for livestock and the advantage of animal manure.
Shelby Filley, PhD in the Department of Animal and Range Sciences at Oregon State University Extension Service, assists livestock grazers with pasture management and productivity.
“There are different objectives with different cover crops. A person might choose deep-rooted species to help improve aeration of the soil and pull up more nutrients to the surface or crops that improve the tilth – or soil condition, and decrease compaction,” she says.
Using the crop
Turn the cover crop under back into the soil like a green manure crop early in the year,” Filley says. “If they choose to graze it a person might be putting livestock out when the soil is too moist and vulnerable to compaction.”
“The cover crop and grazing season need to fit with climate and objectives,” she explains.
Additionally, Filley notes cover crop grazing can accelerate the breakdown of plant tissues, adding more litter and manure to the soil.
“It speeds the whole process,” she says. “Rather than turning the crop under and letting it rot, running it through the animal hastens breakdown with the microbes of the rumen.”
“Traditionally, cover crops have been a temporary crop so the soil won’t remain bare while it’s fallow. Then, the cover crop can be incorporated into the soil by tillage the next season, before planting another crop, or producers can do intercropping in rows with the cover crop,” Filley explains.
The nutritional value of cover crops is usually very high because they are generally young and in a vegetative growing phase when grazed, Filley explained.
“Producers just need to do a bit of homework to make sure the grazing doesn’t interfere with the purpose of the cover crop and also investigate suitability for livestock – including which types of plants would be good for grazing as well as for cover,” says Filley.
When selecting a cover crop, Filley encourages producers to ensure there are no harmful alkaloids, nitrates or other toxic properties or physical characteristics that might cause problems.
“A person also needs to consider things like bloat or possible choke. Phytoestrogens – substances that mimic the animals’ own estrogens – can be a problem with certain clovers as cover crops. It pays to investigate suitability for grazing,” she says.
Filley explains, “When producers start using the crop as feed, introduce the animals into it cautiously, as with any type of new feed,”
She continues to explain it often pays to give livestock a full feed of hay before moving them into a pasture or to move them in after they’ve already filled up with morning grazing in their previous pasture so they don’t go into the new crop hungry and eat too much at once the first day.
“This helps them adjust to the new feed a little more gradually,” she says.
Filley also suggests strip grazing cover crops to get the most benefit, moving the animals across the field with portable electric fencing so they can use one portion efficiently before moving into the next.
“In Oregon, we often use annual ryegrass as a cover crop. It grows so quickly it can often be grazed within six weeks of planting,” says Filley.
When people need a good cover crop for erosion control, Filley usually suggests annual ryegrass just because it does comes up fast and the seed is less expensive than many other species.
“It works well in a moderate climate, especially for producers who don’t live in an area with extremely cold fall weather,” Filley explains. “Even if it stops growing and dies in late fall, there would still be grazable plant material that would provide forage.”
Filley also encourages producers to find plants that work well in their climate and, when trying something new, plant it in a small area at first to see how it performs under the specific farm conditions.
Traditional cover crops include legumes like crimson clover, peas, vetch and oats.
“There are a number of good forage crops that can work for extending summer grazing season – either early before the typical pasture is ready for grazing or late into the fall and winter. If a person needs to renovate a field or change it over to something else, this is the perfect time to try a cover crop that can be grazed to add some extra forage to the grazing system,” she explains.
Heather Smith Thomas is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to firstname.lastname@example.org.