Two grants, completed at the end of 2015, explore ways to improve pastureland health. One grant, begun in 2012, looked at short-term mob grazing to improve grassland productivity. The second grant researched the impact of patch-burning to manage tall fescue in grazing land. Both research projects had similar goals of providing a win-win situation to improve habitat for wildlife while enhancing grazing options for cattle producers.
The project “Enhancing botanical composition, wildlife habitat, and carbon sequestration of pastures in south central Iowa through soil disturbance by mob grazing of beef cattle” (E2011-06) was led by James Russell, Iowa State University animal science professor.
Mob grazing is the act of moving a number of cattle to a concentrated pasture area, where they graze heavily for a short time period, and then moving them to another pasture area, allowing the grazed portion to rest and regenerate. Russell wanted to examine the effects that mob grazing might have on plant diversity, carbon sequestration, wildlife habitat, and water infiltration.
The research area was located in south central Iowa; where rolling hills and highly erodible land are less suitable for row crops and better for livestock. Russell used high densities of cattle grazing for shorter time periods to see if there would be changes in perennial plant diversity including the establishment of legumes and annual grasses. Plant diversity helps with livestock production, increases carbon sequestration, improves water quality, and enhances wildlife habitat.
“In Iowa, mob grazing doesn’t seem to be a practical season-long system,” says Russell. “But it could be used strategically in the spring on a portion of pasture in a single grazing event every three years to obtain the desired changes in botanical composition and structure of the plant community. The amount of labor needed would be reduced to make this a practicable tool.”
In addition to aiding plant diversity, helping grasslands that have been in set-aside programs or used for hunting, high density grazing “could provide a win-win situation of improving habitat for wildlife while providing grazing land for cattle producers,” says Russell. He warns that many factors need to be considered when looking at using mob grazing for pasture improvement such as timing, duration, intensity, location, stock density, and soil moisture.
ANOTHER TOOL FOR GRASSLAND MANAGEMENT
Tall fescue, a cool-season grass, is predominant in Iowa pasturelands, and with proper management it is a preferred plant for livestock grazing. However, tall fescue can be considered invasive if left unmanaged and allowed to take over pastures during the warmer months. When mature, tall fescue can host a fungus that produces toxic alkaloids which can cause fescue toxicosis in grazing cattle.
The recently completed grant “The complex role of tall fescue in grassland ecology” (E2012-01), looked at whether patch-burn grazing could reduce the dominance of tall fescue in grazing lands. The research team was headed by Diane Debinski and Karen Jokela, both with the Ecology, Evolution and Organismal Biology Department at ISU, in collaboration with Dave Engle and Derek Scasta, Oklahoma State University, and Rebecca McCulley, University of Kentucky.
In these grazed systems, by burning one-third of a pasture each year, instead of burning the entire pasture every three years, Debinski her colleagues hoped to find that the less desirable tall fescue and woody plants can be reduced relative to native grasses and forbs.
Their research was conducted in the Grand River Grasslands of southern Iowa and northern Missouri on privately-owned land as well as land owned by the Department of Natural Resources and The Nature Conservancy.
Debinski found that patch-burn grazing by itself may not eliminate tall fescue, application of herbicide also may be necessary. However, this work illustrates that patch-burn grazing can increase consumption of endophyte-infected fescue by cattle with few apparent negative consequences.
“The goal is to have the cattle select for the patch that was recently burned, rather than selecting a specific type of plant,” says Debinski. “Sites that have been recently burned provide more lush, green grasses and forbs for grazing and the cattle find these locations to graze within the pasture. That selective grazing creates structural and compositional heterogeneity within the grassland.” She says that “grasses and flowering plants respond very quickly to burning, coming back within weeks depending upon the season.” They conducted their grassland burning in the spring, so when combined with warmer temperatures and spring rains, the plants grow rapidly.
“In some cases, the woody plants can be killed by fire, but this is part of the goal—to stimulate growth of the native grasses and forbs of the grassland ecosystem,” says Debinski.