Silvopasture Can Mitigate Climate Change. Will U.S. Farmers Take it Seriously?
Steve Gabriel curls back a bit of flimsy net fencing and shakes a plastic bucket of alfalfa pellets. Immediately, a sweet-faced, short-fleeced mob of some 50 Katahdin sheep pull away from a line of young black locust trees on whose leaves they’ve been snacking and swarm around him. The sheep race after Gabriel as he strides across nibbled grass and out from the fencing, around a dirt path’s shallow curve, and into a shadier, overgrown pasture dotted with longstanding black walnut and hawthorn trees.
Gabriel is an agroforestry specialist at Cornell University’s Small Farms Program. He’s also the author of the book on silvopasture, a farming technique that’s touted as a way to sequester carbon by growing trees in livestock pastures.
Trees absorb and sequester large amounts of carbon over time; they’re rendered even more powerful when they’re used in concert with grazing and planted on “marginal” land that isn’t great for growing crops—what Gabriel calls the “funky edges” around, say, healthy woodlands. On the heels of the latest, dire, National Climate Assessment, ag-based climate solutions such as silvopasture could provide much-needed climate benefits—if they can be scaled up.
Project Drawdown, a group of international scientists and policymakers that modeled the 80 most effective ways to battle climate change, ranks silvopasture number nine on its list, reporting that it could reduce CO2 emissions by over 31 gigatons by 2050 if it were ramped up from its current 351 million acres to 554 million acres worldwide.
There are no good estimates of how much land in the U.S. is currently devoted to silvopasture. The amount, though, is small, which means there’s potential for the practice to play much a larger role here; worldwide, it accounts for about 15 percent of all grazing land.
This prompts the question: Can more American farmers get the message about silvopasture’s positive qualities, and can the resources necessary to get them started with it, or transition to it, be made more readily available?
How Silvopasture Works
Gabriel addressed at least the first part of that question in his book. It’s a primer on ways to mingle silva (Latin for forest) with the pasturing of livestock—as well as a look at ancient silvopasture methods in Spain’s dehesa and Japan’s Kyushu province, plus more recent efforts in places like Mexico, where it receives government subsidies. The method has also been adopted in Panama, Costa Rica, and Colombia.
Much of the knowledge Gabriel is passing on he’s accumulated through first-hand experience farming with his wife Elizabeth on their 35-acre operation outside Ithaca, New York. There, they’ve been fiddling with a system that works like this: The sheep, which the Gabriels raise for meat, rotate daily on one-acre grazing plots. On a couple of those plots, which contain seeded-in and naturally occurring grasses, they’ve planted those fast-growing black locust trees to provide shade (more and more necessary in a rapidly warming world) and some forage for the animals, as well as fix nitrogen and hold a whole lot of carbon in the soil—anywhere from 3 to 10 tons per hectare (roughly 2.5 acres) per year. Eventually, Steve Gabriel says he might chop the trees down for rot-resistant fence posts, which will fetch a high market price, even as they retain the carbon stored within their wood.
It’s been five years since they began working what was depleted, degraded, and unproductive hay land. In that time, he says, “We’ve seen a transformation of the soil and the vegetation, with increases in organic matter and a big shift in soil biology—from the bacteria-dominated soils you get in open pasture to the fungi-dominated soils you get when you bring in trees. And the animals do all the work.”
In some of their woodsier plots, the sheep have nibbled down the underbrush. This creates areas suitable for their shelter and for seeding in new, more nutritious grass and forb forages; it’s also freed up wild apple trees the Gabriels harvest for local cider-makers.
On the remaining, densely forested plots—which are massive carbon sinks in their own right—the Gabriels practice what agroforestry specialist Eric Toensmeier, who contributed research to Drawdown, calls multi-strata agroforestry (#28 on the Drawdown list): thinning out maple stands he taps for syrup and clearing ground for stacking logs on which he grows shiitakes for area restaurants.
This idyll—animals, trees, and forages working in tandem to fill a dual purpose of regenerating soil and climate and creating a sustainable, financially viable farm—belies certain challenges. According to Steve Gabriel, silvopasture’s fundamentals are well understood, but a lot remains unknown about how it functions in multifarious climates and soils with different combinations of trees and animals.