Hedgerows: Can They Help Save the Planet?

Photo: Hedgerows are straightforward strips of shrubs or trees roughly 15 feet wide, and they highlight nature’s complex work. (Sierra Orchards)

More than 20 years ago, Craig McNamara started planting woody vegetation on his family’s farm , west of Sacramento, California. McNamara was an early organic pioneer in the region, and he prioritized weaving nature into the agricultural landscape at a time when it was far from popular. Native shrubs and trees lined a creek that ran through the walnut farm. Plants became boundaries between orchards and row crops—i.e., hedgerows—and it didn’t take long for the 450-acre organic farm to come “alive,” says Craig’s son, Sean McNamara, who joined the operation in 2014. Bees, owls, ladybugs, and many other creatures still routinely visit the farm. Just a few weeks ago, a bobcat strolled through the bushes along the creek.

These above-ground benefits to hedgerows are easy to spot. But a few years ago, McNamara watched as a soil scientist dug into the dirt surrounding them. She scooped up rich, dark, compacted soil, mycelial strands tangled within. “I think we were in the middle of summer and the soil, even the topsoil, was moist,” he recalls. It was a memorable sight in drought-riddled California.

That scientist, Jessica Chiartas, was studying the soil around hedgerows. She selected a couple dozen farms in the Sacramento Valley, an area with plenty of well-established hedgerows thanks to a campaign initiated more than 20 years ago that sought to bring native vegetation back to local farms.

Chiartas’ study, published in late 2022, found that no matter the soil type, be it loam or clay, the soil below hedgerows stored significantly more carbon than the soil in the adjacent agricultural fields. While most of that carbon remained on the surface layer, an increase in soil carbon was detected down to the depth of 1 meter—where it’s more likely to remain. In fact, the study concludes that installing hedgerows on 50 to 80 percent of California’s farmland would capture so much carbon, it would help the state to reach up to 12 percent of its ambitious greenhouse gas reduction goals.

California farmers, who are contending with drought, flooding, and a long list of pests that can ruin fruits, nuts, and vegetables haven’t fully embraced planting native vegetation adjacent to fields. But as the state encourages and incentivizes climate-friendly agriculture practices, they might just start.

Hedgerows are straightforward strips of shrubs or trees roughly 15 feet wide, but they highlight nature’s complex work, says Chiartas. At the surface of the soil around them, “you have a buildup of litter: leaves, stems, dead insects, feces, whatever organic materials are deposited,” she explains. When it rains, the organic matter dissolves and moves deeper into the soil profile. That “litter layer” also protects soil temperature and moisture, creating a stable, thriving soil food web that pulls organic materials deeper into the ground. “We’re not fighting biology,” she says. “It’s efficient.”

Recognizing that, the USDA’s Natural Resources Conservation Service (NRCS) offers a program to farmers nationwide that provides technical assistance and some funding for hedgerow planting, and Xerces Society for Invertebrate Conservation has also focused on the expansion of pollinator habitat, including hedgerows. Individual states including Minnesota and Iowa have also encouraged the planting of native vegetation in the form of prairie strips.

Chiartas jokes that she’d like to start a campaign to “re-hedge California.” With millions of agricultural acres, she sees potential in otherwise long stretches of empty perimeter. “All these field edges are bare right now,” Chiartas says, adding that because hedgerows stay in place, the carbon benefits would last […]

Full article: Hedgerows: Can They Help Save the Planet?