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Cover crop research finds varieties to fit Southeastern Wyoming

by Wyoming Livestock Roundup

Cody – According to Jim Krall of the Sustainable Agriculture Research and Extension Center (SAREC) at Lingle, there are a lot of reasons to plant cover crops, one of which is to biologically fix nitrogen in the soil.
    Krall presented ongoing Wyoming research on cover crops as a part of the Soil and Water Conservation Society’s (SWCS) breakout sessions in Cody at the early November joint annual meeting of the SWCS Wyoming Chapter, The Wildlife Society Wyoming Chapter and the Society for Range Management Wyoming Section.
    Krall shared research on peas, vetches, lentils and annual medics, some of which he’s brought to Wyoming from his time spent with crops specialists in Australia, whom he says are way ahead of where the U.S. is in their use of biological nitrogen.  
    “They’ve come up with some values that say a ton of dry matter forage above ground will put down 18 to 22 pounds of nitrogen,” said Krall. “When you consider 40 percent total nitrogen below ground, that comes to 26 to 32 pounds.”
    A pea released a few years ago that Krall researched – the Forager variety – was refined mainly for forage production. “Across 15 trials it out-yielded more popular forage pea varieties by 780 pounds per acre,” he said.
Austrian winter peas
    Krall has also been working with spring sown Austrian winter peas as a legume superior in forage production potential. He’s also researched the crop as a winter annual.
    “We’ve found that fall-sown Austrian winter peas seems to do as well as any of them,” he noted. “There’s quite a bit of difference in seed size from Forager, and it’s smaller than a normal pea so that reduces the cost of seed and it’s readily available in southeast Wyoming.”
    However, he says recently there have been shortages because its popularity is increasing.
    “We plant it in grain residue, in moisture and treat it like wheat,” he said. “Then we allow the snow to come along and insulate it.”
    So it can be produced in Wyoming, but how can it be used? Krall said a Western SARE grant is funding a study to look at grazing sheep on Austrian winter peas at the Archer Research Station near Cheyenne.
    “We’ve had pretty good success, and the sheep seem to eat it well with high consumption,” he said, noting they got 138 pounds of lamb gain per acre.
    “We feel we were able to double the rate of return compared to fallow by fall planting Austrian peas, pasturing early in the spring and getting the pasturing done by first of July before terminating the crop,” he added.
    Currently there’s a proposal in with USDA to graze cattle on a pea/cereal mixture. “There’s limited experience with that, and in our region the primary livestock resources are cattle, so it’s important to see how cattle perform on peas,” said Krall.
Vetch varieties
    In addition to the Austrian winter pea Krall has been researching vetches, including hairy vetch and woolypod vetch.
    “The important thing with cover crops is the quicker the better,” said Krall. “The Laramie medic was ready to go and produced forage over two tons per acre by mid-May, compared to the hairy vetch that was a month later in production.”
    He said the woolypod vetch is earlier flowering and maturing in southeast Wyoming than the hairy vetch.
    “Based on the environment in this area, the Austrian winter pea is good, and the Laramie medic and hairy vetch are excellent in winter survival,” explained Krall. He said lentils in general were poor in survivability.
    Krall said another dimension of cover crops is hard or soft seed, or how likely the crop is to volunteer during the next crop. He said woolypod and hairy vetches have some potential to volunteer and be very aggressive in their growth habit, but the Austrian winter pea is very soft-seeded.
Laramie medic
    Regarding medics, Krall said because they’re vegetatively very prostrate, unlike alfalfa, they’re not competitive during the wheat phase because they get shaded out and when you want pasture you let it go. They also have a self-sustaining nature.
    “I asked a farmer in Australia when he’d seeded the medic in his field, and said he’d seeded it 37 years before,” noted Krall. “Growers also don’t have to put on nitrogen because they get it from the medic, and it provides pasture for sheep and cattle.”
    Krall says his research team will continue to work to find annual legumes to fit southeast Wyoming’s environment. Pea breeding work to develop winter annual peas is looking at a very upright pea with tendrils that would be easier to produce for seed compared to the Austrian winter pea.
    Of cover crop research in other parts of the state, Krall says there aren’t any trials in the Big Horn Basin, and he welcomes anyone who wants to work with him on some of the new varieties and strategies in other areas.
    Christy Hemken is assistant editor of the Wyoming Livestock Roundup and can be reached at

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