Complicated thoughts about pastures and pollinators
Understanding the economic role of pollinators is the first step toward understanding their diverse values to grassland and crop systems, explained Pete Bauman, SDSU Extension range field specialist.
"I encourage landowners to consider the role pollinators play when developing a pasture or CRP weed management plan," he said.
The term 'pollinators' Bauman said, typically refers to the suite of plants that produce nectar and pollen (generally flowering broadleaf plants) and the insects and other animals (birds, bats, etc.) that spread the pollen for plant reproduction.
"In the last several years, the honey bee has been at the center of the pollinator discussion, as their populations have crashed - placing bee keepers and their fruit and nut producing clientele at risk," he said. "I remind folks that along with honey bee decline has come the dramatic decline of local butterfly species, including the iconic monarch butterfly."
Pollinator's survival depends on what we plant
Much of our success in food production can be attributed to technological advances. "For instance the advent of chemicals for weed control has made farming quite different than it was decades ago. Along with the cropland chemicals, advancements in chemicals formulated for broadleaf plant control in pastures also continues to develop. These chemistries can be a great tool, but they can also be detrimental," Bauman said.
He explained that as with any tool, the tool itself cannot be heralded or demonized - it is the appropriate application of the tool that creates successes and failures.
With this in mind, Bauman said there are many factors that play a role in the overall decline of pollinators. "Use of herbicides and insecticides in crop production and conversion of native grasslands to farming are viewed as major contributors," he said. "However, we cannot overlook the critical responsibilities of pasture managers in this discussion."
On one hand, Bauman explained, if it were not for our remaining native pastures many of our pollinator species would be in worse peril than they currently are.
"Our ranchers should be applauded for their efforts in protecting grasslands," he said. "But in fairness, if it were not for current pasture management philosophy, many of our native broadleaf pollinator species would be more abundant than they are, and pasture managers should seriously consider their responsibilities in that regard."
Producers often look at pastures through the same lens that they view cropland. A common desire is to want the pastures 'cleaned up.' Simply stated, Bauman said this means removal or control of anything perceived to be unpalatable to cattle or any species simply not recognized as contributing to the pasture ecosystem.
"Through heavy stocking rates and broad scale chemical applications, we've collectively managed our pastures toward grass-only systems that not only impede the survival of broadleaf plants, but also impede the sustainability of our best native grasses," he said. "Often, this leads to weed problems."
With spring upon us, Bauman said this point will be illustrated plainly over the next several weeks as South Dakota's pastures come to life.
"The early green-up will primarily be the result of heavy infestations of Kentucky bluegrass and smooth brome that have largely replaced native cool season grasses," he said.
Both are non-native exotic grasses that, although palatable early in spring, can indicate poor range health, he explained. "Look closer and these are the same pastures that are prone to wormwood sage, leafy spurge, thistles, and mid-summer browning due to lack of native warm-season species," he said.
Bauman explained that the challenge in range management is balancing legally required management (such as the control of noxious weeds) with integrated management tools that allow our native systems to flourish. For example, identifying early infestations of invasive species and either chemically spot treating or mechanically removing them is much preferred to the alternative of waiting for the problem to grow and then reacting by attacking in full force with non-selective herbicides formulated primarily for grass-only retention.
"Pasture management should be focused on true objectives rather than perceived problems," Bauman said. "Managers who consider pasture production and diversity as a top priority have a much different 'weed management' program philosophy than those focused solely on cleaning up the pasture."
Plants signal health of grassland
Cattle will include a great many broadleaf plants in their diet if given the opportunity, up to 20 percent or more, said Bauman.
"These broadleaf plants play a critical role in the overall function of rangeland nutrient cycles and soil health," he said. "Infestations of common plants such as ragweed, goldenrod, gumweed, buckbrush, prairie coneflower and other less desirable native broadleaf plants may indicate a need for a shift in grazing management rather than a three to four year spray rotation."
Although judicious use of chemicals for targeted control of certain species may have a place in a well-managed operation, Bauman encourages producers to ask themselves if their own management methods are the primary cause of the weedy infestation and thus the need to apply broadcast chemicals in the first place.
"Careful evaluation of targets may indicate that emphasis asking 'why' weeds persist rather than simply focusing on the weeds may lead to more efficient distribution of input expenses (labor and chemicals), resulting in improved and long-term rangeland health and profitability," he said.
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