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Sea Level Rise Is Already Changing What Farmers Can Grow

John Zander’s family has owned a stretch of land along New Jersey’s southern coast for 30 years, but he only recently dubbed the farm “Cohansey Meadows.” Cohansey for the river that runs through it. Meadows for the term that residents of the region use to refer to the vast marshes that create a fluid transition between solid ground and the water of the Delaware Bay.

“This portion is a field, this portion is woods, this is marsh—it’s kind of all intertwined,” he explained while walking a road that August rains had turned to mud. In a nearby wooded area, insects hummed. In an open space where grasses stretched to the shoreline, ospreys flew overhead, dangling fish in their talons.

For decades, his family used the marshes for muskrat trapping and duck hunting and leased the drier land to farmers who grew corn and soybeans. But as salty water from the bay began to encroach, he realized they’d have to reimagine what the land could provide.

“As far as commercial production of corn and soy, it’s probably not viable anymore,” Zander said. As a result, he’s been asking himself, “What can we grow in these really harsh conditions? How can we turn this into an advantage?”

John Zander, project manager at Cohansey Meadows Farms in Fairfield Township, New Jersey. (Photo credit: Mattie Cameron Rosen, NJ Spotlight News)

With the help of state grant money, Zander will be planting test plots of various tidal grasses. Unlike most crops, the grasses don’t mind being submerged and can hold salt in their roots and excrete it through glands in the blades. During storms, their dense root system slows down encroaching flood water, helps the land absorb more of that water, and prevents erosion. He plans to harvest some grasses as hay for animal bedding and weed control. The rest he’ll sell as “plugs” to other farmers to plant their own field buffers and to conservation groups for wetland restoration projects.

While the markets for these grasses are barely established, it’s one potential solution to a clear problem: In the coming years, as the effects of climate change intensify, growers in this and other coastal regions will have to farm differently. What exactly that will look like is still developing and it will likely include growing new crops in new places. Zander’s crop of choice is novel because not only can he grow tidal grasses on land where saltwater is moving in, but he can then sell them to be planted in other places to rebuild wetlands and create field buffers, protecting other farm landscapes from the same fate.

“What can we grow in these really harsh conditions? How can we turn this into an advantage?”

States further south, such as Florida, have been dealing with the phenomenon known as “saltwater intrusion” for much longer, and Louisiana has recently faced the high-profile threat of it disrupting drinking water supplies. But farmers in the Mid-Atlantic are likely to see it more often in the coming years. The region has been identified as a current and future hotspot, explained Chris Miller, a conservation agronomist who runs the U.S. Department of Agriculture’s Cape May Plant Materials Center, about 40 miles east of Cohansey Meadows on New Jersey’s Atlantic coast.

Scientists at the National Oceanic and Atmospheric Administration (NOAA) predict that sea levels along the East Coast will rise by about a foot over the next 30 years. Exactly how far inland the salt encroaches will depend partially on how effective humans are at reducing greenhouse gas emissions, as rising temperatures and melting ice sheets are the main contributors to the ocean’s expansions.

In July, a team of researchers led by Kate Tully at the University of Maryland published a paper that mapped the extent of saltwater intrusion onto Delaware and Maryland farmland on the Delmarva Peninsula for the first time. The peninsula is a low-lying land mass between the Chesapeake Bay and the Atlantic Ocean, where farmers growing corn and soy for chicken feed increasingly find patches of their fields white-washed with salt. According to the researchers, between 2011 and 2017 the number of visible salt patches almost doubled and about 20,000 acres of farmland turned into marsh.

“Even though it’s still a relatively small amount of cropland that’s currently impacted by salt, it’s increasing exponentially because sea level rise is increasing and the number of storms we’re getting is increasing and the intensity of storms we’re getting is increasing,” Miller said of the region.

New Jersey’s farms, just to the north, have not yet seen this degree of impact, and the U.S. Geological Survey is still working on quantifying the problem in the state. But people like Zander and Miller are working to establish systems that work as they watch the issue manifest in real time on the ground. “I hunt, I trap, and I’m also a conservationist. I know the habitats. I walk the ditches. I see the changes,” Zander said.

Looking to the Past to Secure the Future

“If you take a soils class in college and you talk about salinity, you’re going to talk about the Dakotas and Colorado and even California,” said Jarrod Miller, an agronomy specialist at the University of Delaware (no relation to Chris). That’s because farmers in dry, Western states have long had to contend with salt in their soil. Without regular rainfall, salt from natural processes and irrigation water sticks around and builds up, threatening plant growth.

To manage it, farmers use specific irrigation methods to flush salt out of the soil or may add gypsum, which essentially displaces sodium with calcium, to their fields. They may also plant crops that can tolerate higher levels of salt: barley instead of corn, asparagus instead of carrots.

John Zander looking at water running through one part of his land with grasses behind him. (Photo credit: Lisa Held)

John Zander looking at water running through one part of his land with grasses behind him. (Photo credit: Lisa Held)

For the past five years, Miller has been working in the fields alongside other Mid-Atlantic researchers like Tully to try to figure out how much of that knowledge can be applied to farms in their region. One important factor is that there are many different salt compounds, and seawater is an elaborate cocktail. Another is that fields where more salt-tolerant dryland crops like barley might thrive have been hard to find.

“You have this dual issue of excess moisture as well,” said Miller, since although saltwater can also enter aquifers from below ground, most of the intrusion to date has been caused by flooding from storms and hurricanes made stronger by climate change.

As Chris Miller puts it, in the West, “They’re dealing more with the salt in the soil. We’re dealing more with the salt in the water. Plus, there’s the double whammy of plants that need to tolerate flooding periodically.”

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