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“It takes a lot of research and a lot of time to figure out what works where,” notes Dave Robison, Legacy Seed forage and cover crop agronomist.

Between 2009 and 2013, Robison and his fellow researchers placed over 450 cover crop plots in Ontario, Canada, the eastern Corn Belt and the upper Midwest to study how cover crops relate to nitrogen fixation.

“When we look at different cover crops, nitrogen production is one of the benefits we’re going to get from them. Several legumes make good cover crops, and how much nitrogen they produce depends on several factors,” he comments.

Many legumes are sold pre-inoculated, but Robison warns growers that some might not be. Inoculated legumes had better success in their research.


Moving into an overview of different crop species, Robison says that Austrian winter peas are a key product in many situations, especially when planted after wheat or other cereal grains.

“In most areas, it will winterkill. It would be nice to have five or six weeks of good growth, and longer is generally better with peas. We can produce 70 to 135 pounds of nitrogen per acre with Austrian winter peas,” he explains.

Field peas are generally less winter-hardy than Austrian winter peas, but they make a good short-term cover crop, produce excellent forage and work well for weed control, according to Legacy Seed research.


Earthworms love crimson clover, often more than other clovers or peas, and the clover can produce up to 140 pounds of nitrogen per acre within a few months.

“This is my favorite cover crop because it can produce a whole lot of nitrogen in a short period,” Robison remarks. “In 90 days following wheat, we have been able to measure up to 140 pounds per acre of nitrogen.”

“Medium red clover is probably the least costly cover crop. Although it rarely happens, it can get too tall in wheat and affect the harvest. We can produce 75 to 200 pounds per acre of nitrogen. It has a good root system, is a good soil producer, is easily killed and makes excellent forage,” he explains.

Yellow blossom sweet clover is another cover crop option, although it hosts the soybean cyst nematode and is not recommended in soybean fields.

Although, Robison remarks, “It is an excellent soil builder – maybe one of the best soil builders.”


Hairy vetch can produce 100 to 200 pounds of nitrogen per acre, and most of its nitrogen is found in the top growth. It generally has a more shallow root system and older varieties may present a challenge with hard seeds.

“I am learning there may be some different varieties coming out with less hard seed,” he comments.

Chickling vetch is generally more costly, but 50 percent of the nitrogen it produces is reportedly available for the following crop.

“Chickling vetch can produce a lot of nitrogen, 60 to 100 pounds per acre, and it’s a crop that really has a lot of promise and benefit if we can get more seed production and get the seed cost down,” he notes.

Other options

Sunn hemp is a cover crop that has gained some recent media attention. The summer legume should be planted nine weeks before a killing frost.

“It can produce up to 120 pounds of nitrogen per acre,” he says, adding that although it has historically been an expensive crop, seed supplies have been increasing in recent years.

“Mung beans are hard to find, so they’re used for sprouting. They're an excellent crop for heat and drought tolerance and a good nitrogen fixer, and the crop can be hayed and grazed,” Robison continues.

Nitrogen scavengers are also important for retaining nitrogen within the soil, and Robison says that radishes and peas are great to use with cover crops and manure.

“We know that turnips are excellent scavengers. There’s not a lot of money spent on advertising turnips, so we don’t usually think about turnips a whole lot when we think about cover crops. But, turnips have very similar scavenging abilities to radishes, and if we’re using the right turnips, we have a lot of soil activity, as well. That can be very beneficial,” he remarks.


Sudan grasses or sorghum-Sudan grasses, milo or other summer and annual grasses can also serve as nitrogen scavengers, with the ability to sequester up to 200 pounds of nitrogen per acre.

“Annual ryegrass is a high risk, high reward cover crop. It can be difficult to kill, and it probably has the deepest roots, but there are millions of acres that have been killed effectively over the years. It probably has the deepest and most fibrous root mass of any of the scavengers that we’re going to be able to find. It’s an excellent scavenger of nitrogen,” he states.

Winter rye can also become a challenge if not monitored carefully, as it can grow and spread quickly in the spring. Yet, it has good rooting depth and winter hardiness and has the greatest opportunity for success planted later in the year with any type of cover crop, according to Robison.

“Even if we have short cover crops, especially when we’re getting into some of our clovers, that doesn’t necessarily mean we aren’t getting a significant amount of nitrogen production,” he comments, adding that the health of scavenger plants can indicate available nitrogen levels in the soil.

Natasha Wheeler is editor of the Wyoming Livestock Roundup and can be contacted at This email address is being protected from spambots. You need JavaScript enabled to view it..

There are many legume crops that can be used as important forage legumes. Alfalfa, the queen of forages, is one of the best legumes, and it can be grown in every state of the U.S. Alfalfa is the number one crop in Wyoming and contributes hugely to the nation’s economy.

However, there are some areas in Wyoming, especially at high elevations, alfalfa does not perform very well in grass mixtures. So, what are other alternatives? Alsike clover is a forage legume that can potentially be used in this scenario.

Alsike clover, also called Swedish clover or hybrid clover, is a short-lived, perennial legume. It is well adapted to southern Canada, the northern U.S. and, importantly, the higher elevations of the western U.S. Being a cool-season crop, alsike clover prefers relatively moist habitats and cool environments. It has good acid and alkaline tolerance and performs well in low fertility and poorly drained soils. However, it does not have tolerance to drought.

The growth of alsike clover is intermediate compared to alfalfa. It has an upright growth habit; hollow, branched stems; and a short taproot. The leaves of alsike clover are a little wider than alfalfa, with toothed leaf margins and prominent veins. The flowers have a small head with beautiful white- to pink-colored petals.

Like alfalfa, alsike clovers can be planted in spring or late summer. The recommended seeding rate is eight to 10 pounds per acre when planted alone and four to six pounds per acre in a mixture. The seed size of alsike clover is very similar to alfalfa, so it should be planted 0.125 to 0.25 inches deep. If the soil is light and sandy, it can be planted 0.5 inches deep. There are a few varieties available in the market to purchase, such as alsike clover 98/85, Aurora and Dawn. It is highly recommended that seeds should be inoculated with alsike clover-specific Rhizobium bacteria for proper nodulation and nitrogen fixation.

Alsike clovers can be used for hay and pasture. It performs better in mixtures with grasses and other legumes, such as red clover and white clover. It is also used for soil improvement. The forage quality of alsike clover is high and comparable to alfalfa. In general, for hay, only one cutting should be made at near full bloom.

Alsike clovers should not be harvested four to six weeks before hard frost. Another side note is that, being a clover and similar to alfalfa, it also has potential to cause bloat problems and may be photosensitive to cattle.

As always, if you want to learn more about alsike clovers or have any specific questions, please feel free to contact me.

Anowar Islam is an associate professor and the University of Wyoming Extension forage specialist in the Department of Plant Sciences in the College of Agriculture and Natural Resources. He can be reached at 307-766-4151 or This email address is being protected from spambots. You need JavaScript enabled to view it..

In November 2012, I wrote an article about Birdsfoot trefoil, its growth and its importance specifically for Wyoming’s environments.

For most Wyoming producers, the terms forage and hay are almost synonymous with alfalfa. Alfalfa is a high yielding hay and pasture crop. However, just as with any other crop, the queen of the forages – alfalfa – has some limitations, too. Grazing alfalfa often results in gas accumulation in the stomach of cattle causing bloating problems. This gas accumulation makes it difficult for the animals to breathe, which can eventually lead to death of animals. Many producers lose their cattle because of this issue every year.

The alfalfa weevil is another major problem for alfalfa growers in Wyoming.

Birdsfoot trefoil, a perennial forage legume, has beautiful yellow flowers and a “bird’s foot” arrangement of pods. Birdsfoot trefoil is highly productive, has high nutritional value and has a long stand life. Its long stand life is due to the fact that it naturally reseeds itself. It performs well on soils too poor for growing alfalfa.

Birdsfoot trefoil also has special chemicals called tannins. Because of the presence of tannins in Birdsfoot trefoil, it does not cause bloat in livestock. Even more importantly, tannins improve protein absorption in livestock, thus improving animal performance. The improved protein absorption due to the presence of tannins reduces the amount of nitrogen excreted and lost in feedlots. This has great environmental benefits in the form of reduced pollution.

These chemicals are important in milk production in cows as well. Thus, feeding Birdsfoot trefoil to cows can increase milk production compared to alfalfa. The non-bloating characteristic of Birdsfoot trefoil makes it an ideal crop for producers who wish to graze it as a monoculture.

Grazing Birdsfoot trefoil as a monoculture can reduce the amount of time and resources needed to cut, bale and transport bales to be fed to animals.

Birdsfoot trefoil has very small seeds, and therefore, smaller amounts of seed are needed for a unit area as compared to alfalfa. The commonly-used seeding rate for Birdsfoot trefoil, 10 pounds per acre, is less than alfalfa, which can help in saving some money for producers.

Birdsfoot trefoil has problems as well. It is slow to establish because of its small seed size. The slow establishment makes weed management critical at the early stages of growth to get a good stand. It prefers soils that are slightly acidic, with a low pH, which is not very good for alfalfa growth.

Scientists at the Plant Sciences Department of the University of Wyoming (UW) have been conducting research over the past few years to identify forage legumes that can resolve some of the problems associated with alfalfa. Field studies are being conducted at the UW Research and Extension Centers at Sheridan and Lingle and also in a producer’s field to evaluate the potential of Birdsfoot trefoil as a forage legume crop.

A good emergence of Birdsfoot trefoil was observed after planting, but weeds initially dominated the stand. Fields were mowed to remove weeds. One mowing was enough to ensure a successful stand establishment. The mowing provided Birdsfoot trefoil a competitive advantage over the weeds and resulted in a well-established stand.

The forage yield, which was greater than 5,000 pounds per acre per year, and quality, at 26 percent crude protein and 195 relative feed value, of Birdsfoot trefoil were comparable with alfalfa.

Birdsfoot trefoil establishes well under Wyoming conditions. However, weed management is critical for better stand establishment. Birdsfoot trefoil produces high forage yield and high nutritional value, similar to alfalfa. With the additional benefit of being a bloat-free forage legume, Birdsfoot trefoil shows promise for use as a new forage legume crop for Wyoming producers.

Anowar Islam is an associate professor and the University of Wyoming Extension forage specialist in the College of Agriculture and Natural Resources Department of Plant Sciences. He can be reached at 307-766-4151 or This email address is being protected from spambots. You need JavaScript enabled to view it..

In December 2015, I wrote an article titled, “Birdsfoot trefoil seems to be a promising forage crop for Wyoming producers.” In that article, I discussed and compared birdsfoot trefoil with alfalfa.

Although alfalfa is a high-yielding hay and pasture crop, often called the queen of the forages, it has some limitations.

For example, grazing alfalfa often results in gas accumulation in the stomach of cattle, causing bloat problems. Excess accumulation of gas makes it difficult to breathe for the animal leading to death in severe cases. Producers lose their cattle because of bloat problems every year.

Another major problem for alfalfa growers is alfalfa weevil, which is very extensive this year in Wyoming.

Birdsfoot trefoil is a perennial forage legume that is highly productive, very nutritious and has long stand life. Its long stand life is related to the fact that it naturally reseeds. Birdsfoot trefoil performs well on soils that are not suitable to grow alfalfa.

Additionally, birdsfoot trefoil contains tannins, which are chemical compounds that prevent bloat problems in livestock. Tannins improve protein absorption in livestock, hence improving animal performance and reducing the amount of nitrogen excreted and lost in feedlots. As a result, this legume provides great environmental benefits in the form of reduced pollution. Because of the non-bloating characteristic, birdsfoot trefoil is an ideal crop for producers who wish to graze it as a monocrop.

Tannins are important in milk production in cows, as well. Compared to alfalfa, feeding birdsfoot trefoil to cows can increase milk production.

Birdsfoot trefoil can also be grown in mixture with grasses.

While birdsfoot trefoil shows several advantages, it has some problems, as well.

The number one problem is the poor establishment. Birdsfoot trefoil is slow to establish because of its small seed size. During the early phase of establishment, seedlings are not very competitive. Because of less competitive ability and the slow establishment, weed management is critical at the earlier stages to get a good stand.

Scientists in the Plant Sciences Department of University of Wyoming have been conducting research on birdsfoot trefoil for last few years, with a special emphasis on establishment. For example, two field studies were conducted at James C. Hageman Sustainable Agriculture Research and Extension Center (SAREC) at Lingle and at a producer’s farm in Torrington, aiming to determine the effects of planting method, cutting frequency and variety on growth, yield and nutritive value of birdsfoot trefoil.

The Lingle study had three treatments using three cultivars, three planting methods and three cutting frequencies. The varieties Leo, Norcen and Bruce were planted using a clean-tilled method, in standing wheat and in wheat stubble. They were then cut once, twice and three times in a growing season.

The Torrington study was at a producer’s large field and had two treatments, using the same three varieties and three cutting frequencies as in Lingle.

Results from these studies showed that the clean-tilled method had the highest dry matter (DM) production, and all varieties used in the study performed equally well at both locations in respect to growth, yield and quality.

Three cuts in a growing season produced the highest DM. However, two cuts in a growing season was economical.

Forage production and nutritive values of birdsfoot trefoil were high and comparable to values found in alfalfa for this region. The average DM production for alfalfa in the region is 5,700 pounds per acre, and birdsfoot trefoil production hit 5,000 pounds per acre.

Birdsfoot trefoil can be established successfully under Wyoming conditions provided that appropriate management practices are in place, especially if weeds are controlled during establishment phase.

Birdsfoot trefoil shows promise to be a good alternative to alfalfa, particularly in conditions where alfalfa is not suitable to grow.

For more information, contact Anowar Islam, an associate professor and the University of Wyoming Extension forage specialist in the Department of Plant Sciences in the College of Agriculture and Natural Resources, at 307-766-4151 or This email address is being protected from spambots. You need JavaScript enabled to view it..

Sometimes non-traditional crops for livestock can augment forage supplies or stretch production on a piece of land. Brassicas are a good example, according to John Snider, who lives in Oregon and works for PGG Seed, a company based in New Zealand. 

PPG Seed, according to Snider, is ahead of the game in producing cultivars that are easier to manage for grazing to add variety to livestock forage options. 

About brassicas

Brassicas are a large family of plants more commonly known as the mustard family, which includes turnips, radishes, rutabaga, cabbage, cauliflower, broccoli, rapeseed, canola and many other plants and vegetables. 

They have many purposes, including some that have been selected and adapted to create varieties for livestock forage. For instance there are now some new varieties of turnip that work much better than the traditional ones and can be planted earlier in the spring.

“There are some taproot varieties today that produce a lot of biomass above ground, which can be grazed two, three or even four times during the year instead of just once,” Snider explains. 


Snider continues, “A traditional turnip grows best in a cool environment and requires 90 to 100 days of good growing weather to get maximum productivity.”

Additionally, traditional turnips require specific planting windows for optimal growth. While the planting timeframes work well in traditional English farming systems in areas with mild summers, in hot, dry environments, the plants don’t thrive.

“In hotter, drier environments farmers need plants that are more adapted to drought. There are several varieties that are easier to grow than the traditional purple top turnip, which does a great job of providing extra feed for cattle in the fall and winter and become grazable earlier – at 40 to 60 days rather than 90 to 100 days,” says Snider.

These can be very useful in climates that utilize warm season grasses like Sudan, sorghum and millet. 


“There are varieties of brassicas adapted to summer weather that can be planted early in the spring,” Snider says. 

The result is two windows of opportunity for planting brassicas – in the spring or in the early fall. 

“We’ve planted forage brassicas, leaf turnips and forage rape in December in California and Arizona. They grow slowly for a while and then by March are large enough to be grazed,” he says. 

In a colder climate, producers would more likely plant in the spring or early summer and graze them through the growing season and still have the turnip bulbs for winter feed.

What to plant

“We now have new kinds of forage brassicas that can be grazed multiple times. They can flower and, after they are grazed, will regrow as a vegetative rather than reproductive phase.” 

If producers graze them off before they actually go to seed, they will regrow and produce another stand of forage. Snider encourages farmers and ranchers to choose a variety that fits their farm or ranch and the time frame when they need to have something available to graze.

He says that choice depends on the timing of planting and timing of grazing in the climate where the operation is located. 

Snider also notes forage brassicas require about the same amount of moisture to start as a new crop of alfalfa, so timely rains or irrigation are necessary. 


“Turnips, for instance, require a lot of moisture because they have a big bulb,” Snider says. “A turnip requires quite a bit of moisture to be a decent crop, whereas some cultivars need less.”

“They all need moisture to germinate and become established, but some of the grazing varieties then get by with as little as six inches of in-crop moisture as they are growing,” he adds.

“There are generic varieties of purple-top turnips and also some proprietary certified varieties produced from foundation seed that have specific purposes for specific climates,” Snider continues

He uses Hunter Forage Brassica and Winfred Forage Brassica as examples. Hunter Forage Brassica is a leaf turnip that is actually a cross between turnip and Chinese cabbage. Winfred Forage Brassica is a cross between kale and turnip. Each variety has different water requirements and hardiness levels, which make them better in certain climates.

“Graza is the only certified forage radish available, created by crossing different types of radish from various parts of the world. It grows very fast and can be grazable in 40 days at the proper time of year,” says Snider. 

All of these new varieties produce more leaf mass and less bulb than a traditional turnip.

Generic varieties

“Today there are many generic radishes and turnips used in cover crops,” Snider says. “There is growing popularity across the country for utilizing a cocktail mix of plants in cover crops for soil health.”

He continues, “These cover crops are also a great cash crop when used for grazing. We only get that added value, however, from using grazing varieties and not just generic radishes or turnips because those all become quickly less usable after they flower. It makes sense to use something that works better for grazing.”

Snider emphasizes, “Some plants are bred to grow seed, and some are bred to grow leaves or roots.”

Just as all wheat, corn and alfalfa aren’t the same, turnips aren’t the same, either, Snider adds. 

“We wouldn’t plant spring wheat we need to plant winter wheat, for instance. We wouldn’t plant corn in mid-December in the northern hemisphere or plant traditional corn in a climate where we need a fast-maturing variety to make ears before frost. Brassicas are a huge family, and we need to know which one might work best in our situation,” says Snider.

Heather Smith Thomas is a correspondent for the Wyoming Livestock Roundup. Send comments on this article to This email address is being protected from spambots. You need JavaScript enabled to view it..