Considering grazing practices can impact health of small acreage pasturesWritten by Natasha Wheeler
Worland – Barton Stam encouraged producers to consider frequency, intensity and timing of their grazing practices to manage small acreages, during WESTI Ag Days on Feb. 20 in Worland.
Stam, a University of Wyoming Extension educator, explained that shifting the impact livestock have on grasses can improve the competitive advantages of desirable species.
“As I go around and look at different people’s small acreages, the number one thing I see that’s probably a mistake is season-long grazing where the plants have absolutely no opportunity to rest from grazing,” he noted.
One suggestion for maintaining healthy pastures is the take half, leave half rule, which guides the amount of biomass that should be left in the field after grazing.
“It’s a utilization range,” Stam said. “What I want us to keep in mind is having a desired utilization rate and figuring out what that is in our grazing plan.”
Stam also encouraged producers to include rest periods in their grazing plans, allowing the grasses to reproduce, set seed and put out more biomass.
“We should look at not coming back into a pasture that we’ve grazed and rested until we get back to an appropriate stubble height,” he added.
Irrigating when animals are not in the pasture can also improve pasture health, as it helps to avoid soil compaction.
“When we get heavy soil compaction, we lose all of the spaces in our soil where air and moisture need to be,” he described.
Next, Stam suggested taking a good look at what species are in the pasture to help determine the best times to start and stop grazing, explaining that a plant like orchard grass will suffer more damage than a plant like crested wheat grass if it is grazed to a very short stubble height.
“If we don’t know what our species are, we can talk to our Extension agents or look them up. Then, we can talk about their different characteristics,” he recommended.
Heat and moisture
Stam also acknowledged that many producers probably gain some understanding of how their grass species grow based on seasonal observations of their pastures.
Soil moisture and soil temperature, he continued, are two important factors that can affect how grasses grow and react to grazing throughout the season.
“It is possible to overgraze at any time of the year, but when we graze grasses, it can affect their opportunity for regrowth,” Stam explained.
Typically, in cool weather with adequate moisture, grasses have a better opportunity to regrow after they’ve been grazed, whereas they may not regrow as well in the hotter, drier months of the summer.
“The reason a plant moves out of a growth stage is because it senses when things are drying out and warming up. It needs to do the one thing all living entities want to do, and that is reproduce,” he said.
If grasses are impacted by grazing, mowing or fire right before they have produced viable seeds, the opportunity for regrowth within that season becomes very limited.
“Most of our grasses here in Wyoming are cool season grasses, so they want to grow in the cool spring. A lot of our grasses, even if we put a lot of water to them, aren’t going to grow as well as they did in the spring once it gets hot,” Stam remarked.
Smooth brome grass, for example, grows very well in the spring but doesn’t come back easily after it has been cut or eaten.
On the other hand, alfalfa and Garrison’s creeping foxtail are examples of forages that do have some regrowth after grazing, as long as they receive an adequate amount of water.
“Are we going to kill a grass if we graze it later in the year?” Stam asked. “Probably not, but if we come back to that same place at the same time every year, that might start to hurt those grasses.”
Grazing considerations may also change based on the seasonality of grazing, such as spring grazing versus grazing over the winter.
“When I think about grazing management in the spring, I’m thinking more about an individual plant’s health. When I go into the wintertime, I’m thinking about more of a landscape scale,” he said.
In the winter, preserving soil resources can be more of a challenge, and keeping ground cover prevents some of that soil from blowing away in the wind or getting washed away in a storm.
Keeping ground cover
“If we have wildlife on our property and we want it to be there, stubble can be a resource for them, and on bigger properties, leaving stubble can provide a reserve if a drought comes in,” added Stam.
Leftover grass in the spring can also serve as an advantage because new grasses have a high water content, which makes it harder for livestock to get the required amounts of dry matter in their feed.
“A cow may need 25 pounds of dry matter per day. If that grass is 80 percent water, she would have to eat 300 pounds of wet matter to get 25 pounds of dry,” he stated to illustrate the point.
Overgrazing a pasture impacts the biomass belowground as well, and Stam reminded producers that roots are the perennial part of a plant, or the part that survives over multiple years.
“If we do too much grazing, not only do we eat all the aboveground biomass but we severely reduce the root biomass as well,” he commented.
Stam also suggested that producers choose forages suitable to their pasture habitats and production goals and continue to monitor species on their land.
“We should use our resources and plan our grazing strategies to keep the competitive advantage towards our good species,” he said.