Adding legumes to grass systems may improve forage value
October 27, 2017
Grass-legume mixtures benefit forage productivity, quality and stand persistence, determined a three-year University of Wyoming study.
While many hay producers already know this, information has been lacking, regarding on optimum seeding mass ratios of grass-legume mixtures in Wyoming conditions.
At least 25 percent legumes in a mixed stand can produce higher yield and quality than monoculture alfalfa and nitrogen fertilized grasses, he said. A 50-50 percent mixture would be the optimum seeding proportion of meadow bromegrass and alfalfa under Wyoming conditions.
Most of the trials conducted by Anowar Islalm, PhD, Associate Professor, Forage Agroecologist, University of Wyoming have utilized orchardgrass or meadow brome as the grass mixed with the legume.
Some grass hay producers in Wyoming apply a significant amount of nitrogen fertilizer to increase productivity, but chemical fertilizers increase production cost and can degrade the soil and environment if not applied carefully. According to Islam's research, legumes can be a two-fer solution. They can fix free atmospheric nitrogen to provide natural fertilizer and grass-legume mixtures could be a good alternative to reduce production costs and increase yield, quality, and stand persistence of forage crops.
If a legume is mixed with the grass, this can improve the quality of the forage, but then the question is what proportion should it be, and how long will this mix persist? "With some mixes after 3 or 4 years the legume is starting to disappear and we no longer get the nitrogen-fixing benefit. Until then, however, we don't need to add any nitrogen to the soil. So the big question is how long a legume can persist in the system so that the stand is still productive, still high quality, etc."
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He started one study in 2009 that is still continuing at different locations in Wyoming. One study was at the James C. Hageman Sustainable Agriculture Research and Extension Center (SAREC) near Lingle (near Torrington) at about 4000 feet elevation, to identify optimum seeding ratios of grass and legume for improved forage yields, quality, and stand persistence. "I did another study at Laramie, which is more than 7000 feet elevation, and a similar study is ongoing in Sheridan, in the northeast corner of Wyoming," he says.
"We use different seeding rates because this is an experiment and we want to answer producers' questions about the best proportions for grass and legumes for a persistent stand." Islam said he planted 15 to 18 treatments at various locations including 100 percent legume, 100 percent grass, and many different proportions of each such as 30 percent grass and 70 percent legume, 50-50 and more. "After several years we found that if you have at least 25 percent legume the stand is very productive and even exceeds the productivity of grass that has 100 pounds of nitrogen applied annually."
Data on each stand is collected every year. One stand, planted in a 50-50 mix measured 45 to 46 percent alfalfa the second year and 42 percent alfalfa the third and fourth years. "We concluded that after 4 or 5 years a 50-50 mix would be very appropriate, highly productive, and fairly persistent. If you plant less than 30 percent legume at the start, the first year it will be good, but after the third year the legume is declining and slowly disappearing from the system. The grass tends to choke out the legume; you don't get the benefit of good productivity for very long, and the quality drops. It's optimum to start with 50-50, and if you go below 30 percent it won't last very long," Islam says.
There are hundreds of brome grasses, but basically two types that are utilized for forage, he said. One is smooth brome (no hair on the leaves) and the other is meadow brome. "Both are very productive, high quality winter-hardy cool season grasses, but the smooth brome is more aggressive. It has more rhizomatous growth, producing a lot of rhizomes under the soil so the plant can pop up in different places," he said. The fast-growing rhizomes can create sod-bound conditions, which can be a problem.
"The meadow brome is better because it is not as aggressive and mixes better with other grasses and with legumes. This is the reason we use meadow brome in many of our studies instead of smooth brome," he says.
Being a winter-hardy perennial, it lasts a long time—longer than a legume. "Meadow brome is a highly adaptable species, especially in the mountain west, and a stand remains productive for 8 to 10 years or more. There are examples of some stands surviving 50 years or more. So we don't need to reseed, if we manage it well. Thus we can have a productive stand for a long time without spending much money. If we don't manage it well, however, the productivity and quality slowly declines."
Since the meadow brome or orchardgrass regrows quite well, you can get a second and often a third cutting from this mix, if you have enough moisture. "In our studies we had irrigation, and normally got three cuttings, and sometimes four." In 2012, when it was extremely dry, they thought we would only get two cuts, but the farm had implemented a water system so they continued to irrigate and got four cuttings. "These grasses and the alfalfa are cool-season plants, and grow well in our summer weather (which is not as hot as Texas, for instance). The alfalfa and meadow brome are very compatible and grow well together, though the alfalfa grows a little faster. If temperature gets very hot, however, neither plant will grow very well. So in our climate, if we are able to supply water, we get continuous regrowth and we are able to get four cuttings," he explains.
Orchardgrass is almost as prolific as brome. "A plot with 50 percent alfalfa and 50 percent orchardgrass produced about 26,000 pounds per acre for a 3 year total, whereas meadow brome and alfalfa produced about 29,000 pounds," Islam says.
Kevin Sedivec, Professor of Range Science, North Dakota State University has also done several trials on grass-alfalfa mixes. "What works here in the northern plains is sometimes a bit different than in other areas. There are only two grasses that grow really well with alfalfa – that enable us to get two crops/cuttings per season of a grass-alfalfa mix. These are meadow brome grass and orchardgrass. Both will both regrow along with the alfalfa for a second cutting." Sedivec said that further south, tall fascue is also useful, and while some northern producers are using it, the grass can winterkill so he doesn't promote it here.
"The meadow brome and orchardgrass really fit well in the Dakotas and western Minnesota but not as well for Montana and Wyoming unless you irrigate. These grasses require a fair amount of water, so when you get into drier climates they are more limited if you want to get multiple crops. In the West, if you have good soils, with good water-holding capacity you can use the meadow brome but not the orchardgrass because it doesn't do well in dry situations and also tends to winterkill in open winters without snow cover to protect it. The orchardgrass fits best in South Dakota and the southeastern part of North Dakota," he explains.
"Those are the two best options if you want a good grass-alfalfa mix that will last many years. We have a stand here at the Central Grassland Research Extension Center that we seeded in 1988 and we still have a good stand today. We've never broken it up, and consistently take two cuttings of the stand. It was planted nearly 30 years ago as a 50-50 mix and today it's about 60 percent meadow brome and 40 percent alfalfa," says Sedivec. This shows the longevity of a 50-50 mix; it doesn't need to be replanted very often.
"Some producers want more alfalfa in their mix, such as a 75-25 percent alfalfa-grass mix, and use a seeding rate to achieve that objective. That mix will still last quite a while; probably in the 5 to 10 year range, then drops to a 50-50 mix due to alfalfa die-off. But if your goal is to always have a 50-50 mixture, the stand can last 20 years or more with that kind of a mix and good management. We've done it here in numerous places. If you want a 50-50 mix you can be assured that it will last 10 years or longer."
TO FERTILIZE OR NOT? – Producers often wonder if they need to fertilize this kind of stand. "My answer would probably be yes, though most people don't. If you want to maximize performance (especially with a 50-50 mix), however, it does pay to fertilize periodically," says Sedivec.
Even though the alfalfa is a nitrogen-fixing plant that adds nitrogen to the soil, it only benefits the grass that grows within 1 to 3 feet of the alfalfa plant. If alfalfa plants are 3 to 5 feet apart, there will be grasses in those spaces that will be lacking in nitrogen. Sedivec recommends adding nitrogen to increase fertility and biomass for the grass, usually by the fourth or fifth year after you've planted this mix, and then fertilizing every other year thereafter. You don't have to fertilize as often as if it was just straight grass.
HAYING AND GRAZING – Whether it's grass, alfalfa, or a mix, you want to bale at optimum moisture level. "This is usually 14 to 16 percent moisture," says Sedivec. The difference in the two plants is that the grass tends to dry down quicker than the alfalfa, especially on the first cutting; it can be a little trickier putting it up just right.
"The second cutting is usually easier because in July (here in our region) the weather tends to be a little drier and hotter, with better drying conditions for hay. We might be able to put it up a day and a half after cutting, versus 3 to 4 days on the first crop," says Sedivec.
The 50-50 mix can also be grazed. "The beauty of a 50-50 mix or less is that cows rarely bloat on it because they generally select the grass first, over the alfalfa, when they graze," says Sedivec. "I don't make a blanket statement that producers don't have to worry about bloat because there is always a cow or two that will seek out the alfalfa and eat more of it. You still have to deal with timing, being careful when you put the cattle on this type of pasture," he explains.
"You want to be sure the dew is off the alfalfa, and that cattle have a full belly when they go out, so they don't overload on alfalfa. The majority of the herd, however, will tend to graze grass first and alfalfa second, which keeps the belly full of grass." Spring can be trickier than summer or fall because of dew in the mornings, he said.
"What we do at the Central Grassland Research Extension Center is take the first growth off in mid-June as a hay crop, and then a second cutting in late July if moisture is sufficient. We normally get two crops because the meadow brome and alfalfa will regrow together. After the second cutting we graze the regrowth, usually from mid-October until we think the cattle should come off. You don't want to graze it too short and expose the buds just before winter, so we graze it at a light to moderate rate. We've done that here, ever since we planted that stand—for more than 2 decades. This same management could also work for an alfalfa-orchardgrass mix.
SAINFOIN AND BIRDSFOOT TREFOIL RESEARCH – Sanfoin is a legume that's sometimes used instead of alfalfa because it doesn't have the risk for bloat. In some conditions it doesn't regrow as well as alfalfa, however, and is best for only one cutting. Islam has done studies in various locations in Wyoming with several legumes including sanfoin. One of those studies is ongoing at Sheridan, using alfalfa, sainfoin and birdsfoot trefoil as the legume, and meadow brome as the grass.
"In one study at Sheridan we used 100 percent sainfoin, 50-50 mix, and 30-70. The test plots at Sheridan using meadow brome (70 percent) and alfalfa (30 percent) produced maximum yield and maximum economic returns, compared to sainfoin. The sainfoin doesn't have a high regrowth rate, compared to alfalfa. If it has too much pressure from grass, sainfoin slowly disappears. Our 4 and 5 year studies showed that a 50-50 mix of sainfoin (or alfalfa) still do ok, but compared to alfalfa and birdsfoot trefoil, the sainfoin is lower. Birdsfoot trefoil does well, and provides nutritive value very similar to alfalfa," he says.
"The sainfoin didn't do as well, in comparison. This was in irrigated conditions," he said. Too much water, too high of a water table or root rot diseases are all hard on Sainfoin. It starts slowly declining in growth in an irrigated system over time he says.
Sainfoin is often grazed rather than put up as hay, because there is no problem with bloat. "It can be readily grazed with no problems. Birdsfoot trefoil is another bloat-free, dual-purpose legume that can be used for hay and grazing," Islam says.
Sedivec has also done some research on sainfoin. "It has become a popular legume in the drier climates of the Northern Plains. I've seen a number of ranchers use it, but the main thing people need to understand is it's a one-cutting legume. You cut it for hay later than you'd cut alfalfa, and there's insufficient regrowth for a second cutting," says Sedivec.
In areas where only one crop is expected, sanfoin might outperform alfalfa, and it is Roundup-tolerant, with one straing being more resistant than others. "But in regions where you could get multiple crops of alfalfa, sainfoin isn't an economical option," he explains. Wyoming, Eastern Montana and some areas in the Dakotas are a good fit for the legume.
Some ranchers in Montana have planted it with cool-season tame grasses like crested wheatgrass, but usually sanfoin is planted by itself because it doesn't compete well. "The sainfoin also isn't as persistent as alfalfa and is usually not a viable stand by the fourth year or fifth year."
Neal and Amanda Sorenson who raise registered Angus on the Powder River Ranch, near Spotted Horse, Wyoming, prefer to feed alfalfa-grass hay. "We buy some and also put it up. We rarely buy straight alfalfa hay," says Amanda.
"We prefer the mixed hay for our cows. The mix is usually higher in crude protein than straight grass hay, meeting nutritional needs of mature cows, and will also give them good fill. It is easy to feed, and if feeding weaned calves you don't have to worry about bloating and killing them like you do if feeding straight alfalfa," she says.
Even though alfalfa has more nutrients and is higher in protein than most grasses, it's lower in energy. The cow converts lower-quality grass hay and straw to energy in the rumen via fermentation breakdown by the rumen microbes, but needs protein to "feed" the rumen microbes. On a cold day, straight alfalfa is not adequate for producing heat energy and cows can't stay warm enough.
"In simple terms the grass slows the digestive tract and cows seem satisfied longer. Alfalfa is a highly digestible feed that will pass through the gut quickly and be more utilized by the cows but they will not stay satisfied as long, or stay as warm on a cold day," explains Amanda.
"We feed a supplement with our grass mix hay that wouldn't be necessary with straight alfalfa hay, but we feel the mixed hay is better for our operation and our needs as far as safety and convenience in feeding and not having to mechanically combine forages to balance rations," she says.
"All our hay fields are dryland, and planted as a grass-alfalfa mix. We do a 1/3 alfalfa and 2/3 grass seed mix when we plant. This enables safe grazing throughout the year and our stands stay productive longer than straight alfalfa plantings. The alfalfa in the seeding mix will "fix" nitrogen in the soil and help the grass stands be more productive without having to fertilize," she says.
Jack Holden (Holden Herefords, at Valier, Montana) raises registered Herefords. He prefers sainfoin over alfalfa in his pastures and hay. "We've had sainfoin mixes (with orchardgrass and brome grass) since 1965; this is what we currently have on most of our pivots. My dad wrote his master's thesis on sainfoin and helped with development of the seed when it first came over from Turkey to Montana State University. He was able to bring some of that seed home so we were one of the first ranches to use it," he says.
"We have enough hay ground that we can put up most of the hay we need with one cutting. We've also put in newer stands of that mix over the years. On our soil, sainfoin stands last much longer than alfalfa." Holden said some 40 year-old stands still produce three tons to the acre. Newer stands produce four or more, and they sometimes get a second cutting, but mostly graze the regrowth. They usually rotate the stands out every 12 to 18 years.
Holden's cows prefer the sainfoin, and sainfoin-grass hay creates more heat energy than alfalfa-grass, he sald. "We still have adequate protein with the sanfoin-grass mixes, but it takes a little more digestion to break down and creates more body heat. The cows are just happier and healthier," says Holden.
Mark and Della Ehlke raise purebred Herefords and Angus near Townsend, Montana. They grow their own hay, including some straight alfalfa. "We like to use alfalfa as a protein source, and we also feed a grass-alfalfa mix. We grow straight alfalfa on certain fields, to mix with straw when we feed it—to meet the roughage requirements of the cattle," says Mark.
In stands of straight alfalfa he uses chemical sprays to control weeds. "We don't use the Roundup Ready alfalfa (that you can spray with Roundup) but there are a couple chemicals available that work with regular types of alfalfa if you time it right—to clean the weeds out. In some stands we'll go back the following year and seed grass into the alfalfa. This gives the perfect mix to feed, and also to market for horse hay. We have a small clientele of horse owners and that's what they prefer to buy."
He is also experimenting with sainfoin and has found it does produce bigger stems than alfalfa when it matures. "We grazed some fall-born calves on sainfoin pastures this summer and they gained three pounds a day. It's a great way to put weight on cattle, once you get a stand established," he says.
In North Dakota, Austin Hager is a fourth-generation rancher at Karlsruhe, and grows a lot of alfalfa to mix with straw.
"We try to keep our stands pure alfalfa, and now have some Roundup Ready alfalfa. If we get weeds or grass we can spray it, to kill everything but the alfalfa. It's more expensive to plant this Roundup Ready alfalfa but we feel that if we can keep the grass and weeds out of it, our stands will last more years before we have to break it up and replant it," he says.