“If there ever was a wonder legume, it’s probably red clover,” said Chris Teutsch at the American Forage & Grassland Council’s annual conference earlier this month in Kissimmee, Fla.
That may be the case throughout the Fescue Belt where red clover is commonly interseeded into tall fescue to offset toxic endophyte, but different species tend to tout the “wonder legume” title in different regions. On farms throughout the conference venue in the Sunshine State, for instance, perennial peanut seemingly takes the cake.
Before Teutsch bestowed the crown on red clover, the forage extension specialist with the University of Kentucky described why it is so valuable to tall fescue stands in the transition zone of the United States. As the primary pasture base for more than 8 million grazing cows in the area between the Midwest and Southeast, tall fescue is an economically important grass.
“Unfortunately, the lion’s share of that tall fescue is infected with a toxic endophyte,” Teutsch said. “That toxic endophyte has positive effects that enhance persistence in the plant, but for the animal, it has some negative impacts.”
Those negative impacts largely stem from vasoconstriction, or the narrowing of blood vessels that impedes animals’ ability to regulate body temperature. This can be especially problematic in the heat of the summer when endophyte toxicity flares in tall fescue and heat-stressed cattle are unable to pump enough blood to their extremities, sometimes resulting in death. Teutsch said it’s an issue that costs the livestock industry over $1 billion a year.
Ideally, the best way to alleviate endophyte toxicosis would be to renovate tall fescue pastures to a novel-endophyte variety. That isn’t always feasible for farmers, though, so the next best solution is to dilute toxic pastures with nontoxic forage, like red clover. But that’s not the only benefit this wonder legume brings to the table.
“After photosynthesis, the second-most important biochemical process on earth is nitrogen fixation,” Teutsch said. “Legumes are a keystone species in sustainable ecosystems.”
Red clover also has excellent seedling vigor and good drought tolerance — not as good as sericea lespedeza or alfalfa, Teutsch said, but good enough for the short-term perennial to withstand typical growing conditions in the Fescue Belt. Another important attribute of red clover is its isoflavones. These plant compounds are vasodilators, essentially reversing the vasoconstriction caused by toxic endophyte.
This opening up of the blood vessels promotes better body temperature regulation and overall healthier animals. What’s more is that by virtue of improving pasture quality and yield, Teutsch said red clover has also been shown to improve fiber utilization by livestock, prevent protein wasting in the rumen, and boost average daily gain when it is interseeded into tall fescue stands.
Another clover candidate
Close behind red clover in contention for the title of the wonder legume is white clover, according to Teutsch. Though it does not offer the isoflavones found in red clover, white clover does have the same nitrogen-fixing abilities and may have a more complementary growth pattern in tall fescue pastures.
White clover spreads via stolons, or modified stems that grow along the soil surface. This ultimately offers a better leaf-to-stem ratio for livestock and makes white clover more tolerable to close grazing; however, that could be to a fault in tall fescue pastures, Teutsch cautioned. As a prolific reseeder, white clover is quick to fill in bare spots where overgrazing occurs.
On the contrary, white clover produces many hard seeds that can lie dormant in soil seedbanks for several years. In fact, these seeds can remain viable for up to 30 years before they germinate. Drought conditions further discourage white clover germination, which is why its presence in mixed pastures can fluctuate between wet and dry years.
Perennial peanut
Following Teutsch and his presentation on cool-season legumes was Jose Dubeux, a forage agronomist with the University of Florida.
“If I had to pick a wonder legume for the Southeast and lower coastal plains, perennial peanut would be a good candidate,” Dubeux said.
Perennial peanut hay is an important commodity in the Southeast, with nearly 30,000 acres of perennial peanut hayfields found throughout Florida alone. However, its integration into bahiagrass pastures is a less common practice that Dubeux and his colleagues are working to promote.
Perennial peanut and bahiagrass get along well, especially because they originate from the same regions of South America, Dubeux said. This combination mirrors many of the same benefits seen in tall fescue-clover systems. Plant-available nitrogen, higher forage yields, and overall better animal performance have all been documented in bahiagrass stands integrated with perennial peanut, which has a nutritive value comparable to alfalfa.
Similar to white clover’s stolons, perennial peanut spreads via rhizomes, which are modified stems that grow below the soil surface. Its belowground biomass equips plants with better persistence and drought tolerance in the hot climate, and it can be a significant storage tank for fixed nitrogen.
One of the setbacks to incorporating perennial peanut in bahiagrass pastures is that it must be vegetatively propagated as commercial seed is not available. With that said, Dubeux suggested perennial peanut comprise at least 30% of a mixed pastures to realize its benefits to bahiagrass or other warm-season grasses. University of Florida researchers have also tried strip planting perennial peanut and bahiagrass to monitor how the legume spreads over time.
After considering each testimony, perhaps there really is no “wonder legume.” Instead, the title should go to whatever species is best suited to your environment. If introducing legumes to grass pastures is the goal, consider the growing season, soil conditions, and animal requirements before selecting a species. In other words, find the legume that will work wonders specifically for you.
