Silvopasture benefits both cattle and trees
In 2016 Steve Rosenow was trying to figure out what to do with the spruce and pine plantation on his land. The Managed Forest Law contract he had on those acres was expiring, and the trees were so crowded it didn’t seem like they were growing much. At the same time, he was wondering if there was a way he could use that land for his beef cows, without cutting down all the trees. After talking to his NRCS soil conservationist he realized that what he was thinking about was a practice called silvopasture.
The word silvopasture combines “silva,” the Latin word for woodland, with the English word “pasture,” and it refers to the management of pasture with trees. Farmers in Wisconsin and across the Midwest are experimenting with silvopasture, and are finding both benefits and challenges.
One of the benefits is shade. Even with moderate daytime highs in the low 80s, cows and sheep like to cool off in the shade of trees. Access to shade improves animal welfare, and when conditions are hot, humid, and sunny for extended periods, shade can improve reproduction and animal performance. However, that love of shade also creates a management challenge. If a pasture just has a few trees, the animals all crowd around those trees. This behavior results in bare soil and too much manure under the trees, and can lead to disease or parasite transmission, as well as tree damage or even death.
That is why one of the first steps to establishing silvopasture is to determine how many trees to keep or plant. Trees should shade between 25 and 50% of the silvopasture. That amount of tree cover leaves enough light for the grass to grow and still provides enough shade for the animals to spread out.
Rosenow worked with a forester and logger to cut two of every three rows of trees, and also remove some of the less healthy trees from the remaining rows. Trees change over time; with more room available trees often respond to a stand thinning by increasing their canopy size, so a thinning operation that leaves 50% shade might fill in to cast 70% shade after a few years.
On the other hand, in the first few years after a thinning the stand may be more vulnerable to wind damage, because the trees are no longer protected from wind by the dense stand. How trees respond to thinning also depends on their age, health, and species.
When farmers establish silvopasture by planting trees, they also have to think about how the trees will grow over time. Open-grown oaks can have canopies 35 or 40 feet in diameter, so just 15 or 20 mature trees could provide 30% shade for an acre. However, the trees will take many decades to grow to that size, and meanwhile deer, rodents, and dry spells can take a toll.
Planting 60, 90, or even more trees per acre can make sense, depending on how much protection and care the young trees will get, the type of tree, and the way they are grouped. Planting trees in rows lets farmers protect young trees from livestock with electric fence, and also makes it easier to manage the pasture, as long as the tree rows are far enough apart to provide equipment access.
It is important to note that silvopasture is not the same thing as letting livestock into the woods. In addition to making sure the trees are spaced properly, rotating livestock frequently is critical, and paddocks usually need longer recovery periods than unshaded pasture. Not only does forage usually grow slower around trees, but animals are more likely to damage the trees by rubbing and by trampling the soil if they are on the site for long periods.
Although silvopasture dates back thousands of years it can be hard to get information about the practice. The Natural Resources Conservation Service in Wisconsin is working on establishing standards for silvopasture, but for now only a few agricultural professionals are prepared to give silvopasture guidance.
Farmers can connect with silvopasture farmers and researchers through groups like the Savanna Institute, and can ask to join a Wisconsin silvopasture list serve by emailing email@example.com. The National Agroforestry Center and the University of Missouri Center for Agroforestry websites also have silvopasture information.
Diane Mayerfeld is the Sustainable Agriculture Coordinator at UW-Madison, Extension