Complicated thoughts about pastures and pollinators
"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.