silvopasture

Tyler Carlson's cattle graze in a stand of aspen trees.

SAUK CENTRE, Minn. — Tyler Carlson is experimenting with silvopasture and, so far, he’s pretty happy with his results.

 “Silvopasture is integrating trees with forage and livestock,” Carlson, who has a herd of 35 Lowline Angus cow-calf pairs, said. “We’re doing two different kinds of silvopasture.”

Carlson and his family planted Norway and White Pine, along with Red Oak, on 20 acres of open field on their Early Boots Farm seven years ago. In a second silvopasture project, they identified 25 acres of wood lot to do managed grazing. 

The wood lot was grazed by dairy cattle and hogs for several decades in the middle of the last century using unmanaged extensive grazing. When the livestock were pulled out, sometime in the 1970s, thick stands of ironwood and buckthorn sprung up among the Red and Burr Oak and other mixed hardwoods.

Carlson’s objective with the managed grazing in the 25-acre woodlot was to rejuvenate the woods while putting some weight on his cattle. 

“What’s different between what we do and what used to be done with cattle is the amount of time we have cattle on the pasture,” he said. “It used to be that you’d put cattle on a piece of pasture for the whole summer. But the cattle can make a pretty big mess of that. It is really about how long they have access to the pasture.”

Carlson will move his cattle through a patch of woods quickly — sometimes moving them twice a day. Over the years he’s also been cutting out the iron wood and buckthorn as well as poor quality ash and aspen. Additionally, he’s planted grass and clover in areas where they will take. The cattle are enthusiastically browsing the buckthorn that sprouts from the stumps.

“There’s evidence that these woods were originally an open oak savannah,” he said. “There are some very large and old oaks — I call them wolf oaks — and we’re trying to use those trees as seed trees by opening up the canopy to let more light in. Then we let the cattle graze through on sort of a flash graze. With that system we’re getting oak regeneration.”

In addition to the new oak trees that are germinating, Carlson in seeing spring wild flowers return.

“I only graze an area once a year,” he said. “I go through once in July and the wildflowers have already gone through their life cycle by then. If I grazed in the spring, things might change.”

Carlson likes the midsummer pass through the woods because the trees provide shade and reduce heat stress. Cattle that aren’t stressed are more likely to graze and browse.

“I’m not weighing them when they go in and come out, but they are pretty happy and I see gut fill when they are in there,” he said. “On the edges where we’ve opened it up, there’s pretty good forage growth of a pasture mix that includes orchard grass and red clover. But usually the first thing they want to do is browse the buckthorn. I move them every day and when they are on a new paddock they seek out that buckthorn and mob it — like five cows to a bush.”

Carlson is seeing definite results in his silvopasture experiment in his existing woodlot. He’s waiting to see the results from planting trees in an open field. 

“Almost all the oaks were girdled the first winter by mice and voles,” he said. “The pines did better. They are planted in two rows of trees eight feet apart and then a 50-foot alley and two rows of trees again. There are some white pine that are nine to ten feet now.”

The small but growing trees are fenced off and not grazed yet because Carlson believes the cattle would damage them.

The alleys are grazed and are planted with a mix of cool season grasses and legumes including white clover, chicory, bird's foot trefoil, timothy, tall fescue, meadow brome and perennial ryegrass. 

“Research suggests that cool season pasture plants, which include most of our pasture grasses and clovers, tend to do well when we’ve got cool nights. They put on a lot of their growth in the spring and fall. When they get too hot their photosynthetic structures start to malfunction and they can go dormant from heat stress or drought. But even if the conditions are right they can only use 50 percent of the light that’s coming to them. So the idea with the trees is that you can shade these plants by 50 percent and still have enough light.”

The trees, when they become large enough, will accomplish two things. They will shade and cool the forage. By cooling the cool-season grasses and legumes, the trees will extend the growing season of the forage. The trees will also capture some of the light the grasses aren’t using. They will turn that light into wood which will be harvestable in the somewhat distant future. But Carlson also likes to think about the trees as carbon-capturing organisms.

“The carbon footprint of a well-managed silvopasture system is one of the best ways agriculture can sequester carbon and keep it out of the atmosphere,” he said. “That’s especially true when we plant trees in open fields. Trees combined with grass in open fields can increase the amount of carbon captured as compared to just grass. The tree improves the productivity of the grass and the trees themselves are capturing carbon. That can positively shift the carbon footprint for livestock production.”