Ron Moss has learned through trial and error some of the things that work best when burning native pasture to control unwanted brush and trees.
During the Manitoba Grazing School this month in Brandon, he shared ideas on how to burn safely and effectively.
He faces an ongoing challenge with brush encroachment on pastures, especially in the northern areas of agricultural Manitoba.
Poplars remain one of the greatest challenges.
“I really don’t like anybody just throwing matches,” said the technology transfer co-ordinator for the PFRA office in Dauphin, Man. “I like prescribed burns where things are planned out.”
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The planning should begin at least a year in advance of the burn. Producers need to leave grass growth on their pasture as fuel for the fire the following year. Moss cited 1,000 pounds per acre of litter as optimal.
Producers might also want to graze adjacent pastures more heavily the year before the burn. Moss described that as a way to establish a fireguard around the pasture chosen for burning.
“Lots of times we’ll graze the field off right next to it fairly hard, just so we have more chance of containing the fire.”
There is debate about the best time to burn for control of poplars on native pasture. Until now, Moss has burned when the trees are dormant, either in early April or in October.
However, he said there could be merit in burning in August or early September. That would damage the poplar trees before they had a chance to replenish their roots with food reserves for the winter.
A drawback to burning in late summer is that it could mean pulling the cattle off that pasture earlier than normal.
Producers who opt to burn in April typically can expect a lot of suckers to emerge, said Moss. There could be as many as 25,000 to 60,000 suckers per acre.
One possible remedy is to graze the area with livestock. Moss suggested late June or early July might be a good time to let cattle in because it takes the suckers time to emerge after burning.
“I believe you should graze it really hard,” he said. “I hate saying this, but continuous graze maybe for that year.”
One burn probably will not be enough to eliminate the brush encroachment. Moss said producers typically will need to do three burns over the course of 10 years to get good control.
“You can’t burn once and then just walk away.”
A fireguard is critical.
Besides heavily grazing adjacent pasture in the year before burning, other options include plowing a band of land along the edge of the pasture or creating a buffer using fire-retardant foam.
Moss encouraged producers to check the weather forecast to avoid winds that could take the fire out of control. He takes into account not only the anticipated wind speed but also the potential for the wind to shift direction during the burn.
When burning out shrubs and trees on native pasture, he finds a wind speed of 20 km-h to be ideal. Wind speeds lower than that may not do a good job of carrying the fire across the pasture and through bluffs.
He prefers the temperature to be at least 13 C when burning to control brush on pasture. “You need that kind of heat to have it dry enough to carry the fire.”
Notify neighbours and the rural municipality in advance of the burn, advised Moss, and get a fire permit if required.
He recommended having at least four people involved during the burn.
“That’s the minimum. I like to have six or seven guys, but I wouldn’t burn with less than four and even that’s borderline.”
He uses what he calls the ring fire method.
“That’s basically establishing a fire line around the whole field of the prescribed burn. Normally what happens is you start on the downwind side and if you have enough people you’ll work both ways from that and just go right around it (the pasture).”
Before using that method, producers need to understand how to manage it to create a back fire.
There are people concerned about the effect burning pastures can have on wildlife. Moss said native plants and animals generally are adapted to fires on the Prairies and he noted that a fire usually does not eliminate all their habitat.
“There’s always a pocket of bushes and slough that the fire won’t carry into. There are areas that animals can escape to.”
Besides controlling unwanted bush, burning of native pasture can have other benefits for producers. Forages in a pasture tend to have higher protein levels following a burn.
As well, burning can help suppress non-native plants such as Kentucky bluegrass, which are not always beneficial to pastures.
There are several ways to control unwanted bush on native pasture, but fire is the cheapest, said Moss, provided it doesn’t get out of control and cause unwanted damage.
