On a warm late-summer day, Delaware farmer Frank Webb stood on a bare patch of dirt in the middle of his Kent County farm.

He pointed to the soil under his feet, which contained visible white crystals in some places.

"If it wasn't for the soil that's in it, you could shake it out of a salt shaker and put it on your steak," Webb said.

Webb's farm in Milford, across the Delaware Bay from Cape May, New Jersey, runs right up to coastal marshes that border the bay.

Between the tall marsh grasses and a field of waist-high soybean plants, a few hundred meters away, a patch of land the size of a few football fields stands bare, made infertile due to high salt levels.

"This used to be all farm production land, grew wonderful crops," Webb said. "And it's rendered now just barren."

Webb's family has been farming this land for five generations, cultivating corn, soybeans, wheat and barley. As long as he can remember, salty water from the Delaware Bay has flooded during nor'easters and hurricanes.

"[In the past] that may happen once every 5 or 6 years, and with continued rainfall throughout the year, it would actually flush the sodium back out of the ground," Webb said.

"[Now] these flood occurrences are happening so frequent there's no chance for any of this sodium to leech."

Salt sucks the water out of plant cells, eventually killing plant tissue if moisture levels dip too low. Webb pointed to a stunted soybean plant growing on the edge of his plot that had some of the yellowing, burnt-looking leaves that are characteristic of salt poisoning.

Webb says close to 100 of his 1,000 or so tillable acres are now ruined from salt water.

"This continues to get worse every year," he said.

A global threat to crops

As sea levels rise and storms are predicted to increase in power, low-lying farms in Delaware and in coastal areas around the world will be increasingly vulnerable to the harmful effects of saltwater flooding.

Rice farms in the fertile Mekong River Delta in Vietnam, a leading rice exporter, have already been turned into saline swamps. International groups are working with farmers there to change cultivation methods and plant salt-resistant rice strains.

Closer to home, Maryland warns that increasing salinity may threaten the health of oyster bays.

In New Jersey, a small 2014 survey conducted by the New Jersey Climate Adaptation Alliance found that 71 percent of respondents named increased flooding as a "great concern" for their farms, and 41 percent said the same for saltwater intrusion.

"Because of its low-lying elevation, and because of issues of subsidence, or land sinking, we are particularly vulnerable to the impacts of sea level rise," said Susan Love, a coastal programs planner at the Delaware Department of Natural Resources and Environmental Control.

A 2012 vulnerability assessment projects that up to 11 percent of Delaware's landmass could be covered with water by the year 2100.

Searching for a transitional solution

Ultimately, low-lying farmlands near the coast may be among those inundated. But until then, as increasing coastal flooding renders land too salty for corn and soy, researcher Jack Gallagher is searching for salt-resistant crops for farmers to grow and sell.

"What we're trying to do is to come up with ways to maintain productivity of that land," said Gallagher, an emeritus professor at the University of Delaware.

For the past 30 years, Gallagher has been studying the seashore mallow, a perennial with intricate seed pods and delicate pink flowers that resemble hibiscus blooms. The seashore mallow evolved in brackish wetlands, and Gallagher's University of Delaware team has been working to determine which varieties are best suited for cultivation. Importantly, they have also been working to come up with commercial uses for the plant.

Gallagher has a greenhouse full of potted seashore mallow plants near his Lewes office, as well as a nearby outdoor test plot. He and his team have ground the seeds to create oil and meal, used for biofuel and rat food. They have made different parts of the woody bark and softer stem interior into cat litter and poultry bedding.

In a study over the winter, Gallagher found the bedding made from seashore mallow was equal to or better than standard pine chips and switchblade grass in chicken coops.

Challenges getting buy-in for new plant

For about a decade, a local farmer has grown a field of seashore mallow for University of Delaware research. Project partners have planted it in China, and this year, researchers at a federal agriculture research station in Cape May have cultivated it to study its viability as a commercial crop in New Jersey.

But Gallagher has not had much luck convincing new local farmers to try the plant, partly because of a chicken-or-the-egg problem of supply and demand.

"When you go to talk to potential growers, immediately they say, 'Well, who's going to buy it?' And right now there isn't anybody to buy it except us," Gallagher said.

Suppliers don't want to commit to using seashore mallow to make, say, cat litter either, until there is a network of reliable suppliers, Gallagher said.

A small problem for the state, but potentially a big one for farmers

In Delaware, about 23,000 acres of "highly productive soil" will be under water if the sea rises a meter, the state's mid-range projection for the year 2100. All told, less than 10 percent of farmland in the state is likely to be impacted by sea level rise.

Susan Love, from Delaware's environmental protection agency, said it is not the top concern for planners.

"In Delaware, one of the biggest priorities is wetlands, and up to 99 percent of our tidal wetlands are at risk of being inundated or permanently flooded by sea level rise," Love said.

"That's fairly huge because a lot of Delaware's economy and quality of life is based on its vast expanses of tidal wetlands," Love said.

Although the total acreage of impacted farmland is relatively small on a state level, it is important to the individual landowner or farmer.

Frank Webb said he plans to hand his land over to his two daughters eventually, but is pushing his grandkids to be doctors or scientists, not farmers.

"My forefathers purchased this farm, and if I had been able to contact them back then I would've said 'let's move inland,' knowing what I know now." Webb said. "It's tough."

Delaware is among the most active states in planning for sea level rise, but it does not yet have a plan for how to deal with cropland rendered unproductive.

Ultimately, Susan Love said farmland may be bought up for conservation, to create a space for wetlands to migrate inland when current habitats are flooded.

Frank Webb seems ready to hand the low-lying portion of his land over for conservation, convinced it would be better as a home for ducks and geese than his crops.