Producers looking to buffer against feed issues may want to add some legumes in their pasture mix.
The concept has been highlighted more than once this seminar season as speakers ponder how to “drought-proof” Manitoba’s feed supply in light of two years of dry temperatures and a significantly short forage harvest in 2018.
Bruce Anderson of the University of Nebraska has been among those pitching extra legumes as a means to cut costs as the nitrogen-fixing plants bite into the need for added fertilizer and to jump-start pasture productivity, particularly late in the year.
Why it matters: Lacklustre forage production last year has producers seeking management strategies to drought- proof their pastures. Adding legumes to the mix is starting to generate interest.
His trials in Nebraska have shown little nutritional difference between bromegrass mixed with legume and bromegrass alone, but with 50 pounds of nitrogen added, for the first half of the season. That same trial, however, showed higher average daily gain in mixed plots in the later season, as bromegrass matured and feed value fell.
Keys for success
Seeding in legumes has gained champions in the livestock sector, with advocates arguing the practice has not only increased pasture productivity and feed value, but that advantages have spilled over into increased soil health, pasture health and biodiversity.
Others have reported more mixed results.
Establishment and competition has been an ever-present challenge, although one that both Anderson and Manitoba Agriculture’s Jane Thornton say can be overcome with care.
“The grass out there has already really got a head start on those legume seedlings and so we really need to make sure that we’ve come up with some method where we can keep that grass from shading out any new seedlings that are developing out there,” Anderson said.
In 2016, Thornton launched a research project at Brandon’s Manitoba Beef and Forage Initiatives, comparing establishment, yield and nutritive value of adding legumes into a forage stand.
“It depends a little bit on your actual forage stand,” the southwest provincial livestock specialist said. “What we found was that when you have a thin forage stand, more of the alfalfa will catch and manage to compete with the grasses because they’re not thick. Any areas where we dropped alfalfa seed in that was very thick grass, you got zero growth.”
Thornton turned to a severe mob graze before seeding the plots, in an effort to stress existing plants and decreasing competitive pressure for the incoming legumes. Others may turn to a chemical stress, Anderson said.
It was possible to increase the amount of legumes in a pasture, Thornton said, although results depended highly on pasture health and weather.
Results showed around 25 per cent alfalfa catch in 2016, a level that Thornton considers successful compared to similar research, but fell the following year, when weather turned dry and hot. Much of the cost from the 12.5 pounds per acre of alfalfa seed was lost in 2017. Last year, establishment dropped to almost nothing as the heat and dry baked pastures in southwest Manitoba.
Thornton found that adding legumes to the mix did, in fact, increase crude protein in stands planted in 2016 and clipped the following year. Plots that had alfalfa sod seeded or broadcast, and then incorporated with mob grazing, had by far the most legumes compared to either control strips or plots that were only fertilized. And while there was little yield difference between fertilizing and fertilized sod seeding, only plots seeded in with alfalfa reached the necessary protein for a lactating cow. Plots that were broadcast, fertilized and had seed incorporated by cattle, meanwhile, produced over 1,000 pounds per acre more forage, and the most alfalfa of all the treatments.
Fertility and clean pastures may help lead the way to success, Anderson said. Producers should be aware of how adding legumes to a pasture might limit future herbicide options, he argued, and pastures chosen for an influx of legumes should already be clean. A shot of phosphorus fertilizer will also give the new crop a boost in comparison to its neighbouring grasses, he added.
The researcher also urged producers to make sure seed is actually getting into the ground, not lost on the surface or orphaned in the litter covering the pasture surface.
Dealing with bloat
Bloat poses another challenge. Farmers may want to turn to other legumes to limit bloat risk if cattle graze unevenly, Anderson said, citing species with less bloat risk such as bird’s-foot trefoil or cicer milk vetch, or keep a tighter rein on management.
Grazing when plants are more mature, bloat-reducing supplements, or turning cattle onto pasture already fed (and therefore more likely to graze moderately) will help mitigate that risk, he suggested. Those looking at grazing management were warned not to clip down a paddock too far before moving on to the next.
“I like to encourage people that when they move on to a fresh pasture with legumes, that they do it more toward midday,” he said.
Where it fits
This year may actually be ripe for producers considering the practice, depending on the growing season to come, according to Anderson. Existing stands will already be stressed due to the dry, he said, and may be easier for legumes to compete. At the same time, he admitted, that assumes that there will be enough rain for the legume stand to flourish, and anyone attempting to add legumes may hit hurdles if last year’s dry weather persists, keeping new seedlings from gaining traction.
Tim Clarke, provincial livestock specialist in the Interlake, considers legumes more of a long-term strategy for fighting drought impact on feed supplies.
“It’s going to take you a whole year to establish them,” he said.
Established perennials, including legumes, may help keep pastures resilient to both drought and flood, he argued, as the deep-rooted plants drain moisture down into the subsoil. Also, he argued, the nitrogen benefits from adding legumes can help bolster other feed yields.
“What I can say is, if you think you’re having good weather, I think it’s worth trying and you have to get the seed on early in the season,” Thornton said, adding that those considering the practice this year should turn a careful eye to weather predictions and start with small acres to limit risk.