Saltwater is destroying crops and threatening livelihoods. How should farmers respond?
The contamination of groundwater and freshwater sources by saltwater – known as saltwater intrusion – is a leading-edge effect of climate change, say environmental scientists.
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elvety-green soybean plants, knee-high and quivering under the sun, stretched off toward a distant road in the U.S. town of Princess Anne — except where farmer Bob Fitzgerald stood pointing at an expanse of dry, barren earth.
“This is what it’s like when it’s totally dead and gone. You can see where I planted the beans, and then they came up, and then they died,” he said, motioning to an acre’s worth of dried, dead seedlings and empty soil.
“And you can see where they’re dying around the edge, where they get into the salt,” said Fitzgerald, 80, who has been farming his 160 acres (65 hectares) of land for four decades but whose family has owned it since the 1600s.
The contamination of groundwater and freshwater sources by saltwater – known as saltwater intrusion – is a leading-edge effect of climate change, say environmental scientists, and one that has officials scrambling.
The northeastern state of Maryland is currently putting together what researchers say is the country’s first action plan for adapting to the problem.
In Fitzgerald’s field, the area tainted by saltwater had long been just a small, low spot, but “it’s just spread and spread and spread. In the last six or seven years, it’s gotten worse,” he told the Thomson Reuters Foundation.
Driving through nearby communities, Fitzgerald pointed out farm after farm that he said were dealing with various stages of salt problems — some experimenting with other crops, some converting their land to other uses, and many giving up farming entirely.
Somerset County, where Fitzgerald’s farm is located, is a region of low-lying land on the east side of the Chesapeake Bay, some 40 miles (64km) from the ocean.
Over recent years, as warming temperatures have caused seas to expand and glaciers and land ice to melt into the oceans, rising sea levels have pushed saltwater into the area through tidal creeks and drainage ditches.
The low spot on Fitzgerald’s land backs up against one such creek.
According to the U.S. Geological Survey (USGS), the Eastern Shore along the Chesapeake is particularly vulnerable to sea-level rise because it sits on a peninsula that is slowly sinking due to long-term geological activity linked to the last ice age.
Sea levels around the peninsula are rising by 3.4mm (0.13 inches) per year — twice the global average, the USGS research found.
Meanwhile, rising tides and the storms and hurricanes that have become stronger and more prevalent due to climate change all help to drive saltwater further inland, said Kate Tully, an agroecologist at the University of Maryland.
“This is an example of climate change occurring within the lifetime of a farmer,” she said.
Bob Fitzgerald points to a historical map of Dames Quarter, Maryland, USA, showing towns and communities that no longer exist. Thomson Reuters Foundation/Carey L. Biron
‘Pervasive’ but unspoken
Elsewhere around the globe, saltwater intrusion has been a reality for years.
In Bangladesh, for instance, salinity levels have risen by more than 25% over the past three and a half decades, affecting which crops can be grown where, according to researchers at the country’s Soil Resources Development Institute.
In Egypt, a study led by French researchers at Aix-Marseille University and published last year showed that nearly a third of farms are already affected.
And the impact is not limited to agriculture, with concern rising over the dangers encroaching saltwater poses to drinking water and the knock-on effects for human health.
But when Tully and a colleague started looking into the problem in 2015, she said they could find only one other American research group looking at the issue of encroaching saltwater and agriculture, and from another state entirely.
But they soon realised the problem is “pervasive” along much of the Atlantic coast – and, it appears, even beyond.
Farmer complaints about salt in the soil in North Carolina are starting to draw attention from researchers and local agricultural offices.
And the federal government is monitoring saltwater intrusion in Florida and California, although not specifically for agricultural purposes.
Somerset County lost about 850 acres (340 hectares) of agricultural land to saltwater intrusion from 2006 to 2017 — approximately 1% of the county’s farmland over a very short period, Tully said.
She is now in the early stages of a five-year research project funded by the federal government to map the effects of saltwater intrusion in Maryland and look into how farmers are adapting and how they could in future.
The state will use the findings of her study to date to draft its new plans, she added. The state government now “appears to be starting to pay attention”, she said.
The state plan, due by December, will look at how saltwater intrusion affects not just Maryland’s agricultural lands but also its aquifers, infrastructure, wetlands and more, said Jason Dubow of the Department of Planning.
It will also identify research priorities to figure out which areas are at risk, understand what those future effects are likely to be, and start sketching out adaptation strategies, he said in emailed comments.
How to adapt
Just as saltwater intrusion has economic and environmental impacts for farmers, so does the way those farmers respond to the problem, said Rebecca Epanchin-Niell, an economist with Resources for the Future, a Washington think tank.
While some crops, such as rice and sorghum, are relatively salt resistant, most are not — particularly corn, a major crop throughout the country, she told the Thomson Reuters Foundation in a phone interview.
Some farmers could continue to farm and put more or different nutrients into the soil to try to neutralise the salt, she noted. Others could switch to alternative crops that may require new nutrients.
Still others could abandon farming entirely, perhaps allowing their land to be restored to wetland, which could potentially let them tap into government conservation subsidies.
“Those decisions have implications for the farmer in terms of profitability and sustainability of their farms,” Epanchin-Niell said.
“But there are also important ecological implications in terms of the ability of a marsh to migrate inland and (affect) water quality.”
Her preliminary research has found that over the past 15 years, there has already been a big drop in corn production in areas of Maryland’s Eastern Shore that appear to be experiencing saltwater intrusion, as well as less agriculture overall.
Those findings support “what we are hearing anecdotally from farmers in the region”, she noted.
Bob Fitzgerald, meanwhile, has tried to raise the low spot in his field by hauling in dirt and added expensive amendments such as gypsum, which can help to remove salt from soil. But, he said, nothing seems to work.
“Unfortunately, there’s not a whole lot I can do about it,” he said. In Somerset County, the effects of saltwater intrusion “just grew up inside us”.
The ideas presented in this article aim to inspire adaptation action – they are the views of the author and do not necessarily reflect those of the Global Center on Adaptation.
