New research from the University of Saskatchewan indicates forage rangeland needs rest to avoid damage from overgrazing.
“It’s an area that we haven’t paid attention to much in North America,” said Jim Romo, a professor in the university’s plant sciences department.
To find out more, Romo and his colleagues conducted studies in the northern mixed prairie range in central Saskatchewan over a three-year period.
“We were trying to attempt to find out how long it takes plants to recover their production capability after being grazed in different months of the year,” he said.
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The forage production potential of northern and western wheatgrass, plains rough fescue and western porcupine grasses were tested after mowing.
Depending on the month and species of the plant, the study indicated it took one to 25 months before the crop was similar to the unmowed comparison crop.
To achieve the most efficient level of forage and livestock production, Romo said growers must allow plants enough time to recover their vigour after grazing.
“Forage grazing reduces a plant’s ability to photosynthesize. If it cannot photosynthesize, it cannot regrow. Therefore, if we give more time to photosynthesize, it will regrow more and faster.”
Romo said producers could notice negative changes in their forage and livestock operation if overgrazing occurs.
“They can expect wild fluctuations in forage production from year to year. They can expect a reduced animal performance and they can expect a whole host of problems that come along with deteriorated range.”
Romo said the exact amount of rest needed by plants after grazing is site-specific, meaning modifications should be made depending on conditions, species and time of year.
“Every site and every forage has its own unique requirements. That’s the take-home message,” Romo said.
“The one thing that we do know is grazing reduces production, but if we’re patient, time will allow that production to come back.”
Romo said the best way to optimize production is to monitor pasture conditions.
“The recommendation I would give is producers need to watch the forage growth. When it reaches the potential or matches what ungrazed or very well-managed pastures are doing, then it’s ready to be grazed (again).”
Managers of hay forage operations understand the importance of providing rest after forage removal, Romo said, but there is a lapse of logical thinking when it comes to overgrazing.
“I think it’s that we just don’t put enough value on our grazing resources.”
Dividing pasture into multiple paddocks does not allow the plants enough time to grow again, said Romo. While the practice can be effective at times, he said he has seen it be unsuccessful just as often.
“It’s a whole integrated operation and timing is just one part of this. The only way to prevent overgrazing is to completely remove animals from a paddock and allow the plants to re-grow.”
One full year of rest after grazing is needed to maintain forage production of plains rough fescue.
The study also noted a deferred rotation grazing system could help maintain production in wheatgrass, porcupine grass and shrubs.
