The Saltwater Soybean

A Delaware research effort is focused on producing biodiesel from seashore mallow. The pink-flowering perennial resembles a soybean plant, and its seeds produce about the same amount of oil. Unlike soybeans, the plants can be grown in salty soil, which makes them a perfect fit for production in shoreline areas impacted by rising sea levels and high tides.
By | November 01, 2007
Seashore mallow could fill a niche as a biodiesel feedstock as the plant's architecture and oil yield are similar to soybeans. Perhaps even more appealing, is that the plant thrives in salty soils where nothing else will grow. In fact, the plant can be irrigated with saltwater.

Seashore mallow or Kosteletzkya virginica is found in the wild, scattered throughout coastal marshlands, says Jack Gallagher a University of Delaware marine biologist. "We've been working with the plant for a long time," he says. Over the years, as Gallagher has studied salt marsh ecology and wetland restoration, he's explored uses for the different plants that grow in these conditions. His work has led to the cultivation of Delaware salt-tolerant forages in the Persian Gulf. In China, the salt-tolerant plants identified by Gallagher's team are used in land reclamation work where the mallow draws salt from newly drained soils. The mallow flourishes as rainfall continues to leach salt from the soil until another salt-tolerant crop like cotton can grow, followed finally by soybeans and corn.

Gallagher expects seashore mallow to serve an opposite function along the Atlantic coast from Delaware south to the Gulf of Mexico. Each year as the sea level rises, high spring tides and storm tides flood more low-lying lands, eventually killing all of the vegetation. "Nothing grows there," he says. "It's a dead zone." Developing a salt-tolerant crop would benefit the farmers who can no longer farm this land, and at the same time control nutrient runoff. "If our long-term strategy is to retreat from the sea as it rises, [seashore mallow] provides an intermediate buffer zone that can keep nutrient runoff from getting into the estuary," he says. "As [the land] reverts to salt marshes, the economics go from being farmland to a nursery growing marine organisms for fish and crabs and the like." Yet another application would be growing seashore mallow on the saline soils dredged from harbors, providing an economic return and a much more attractive ground cover than the invasive weeds that currently sprout there, according to Joseph James, CEO and president of the Corporation for Economic Opportunity in South Carolina, who is collaborating with Gallagher in promoting the crop.

Grown Like Soybeans
At the University of Delaware's College of Marine Studies, seashore mallow was initially evaluated as a potential food or feed crop, Gallagher says. Analysis showed that the oil is similar to cottonseed oil as cotton is a relative of seashore mallow. Flour from the plant's high-protein meal was used to make bread and the meal made an acceptable feed for laboratory animals, he says. About three years ago when biofuels production started to take off, the Delaware team targeted biodiesel as a potential use.

Although seashore mallow thrives in marshes the plant can also be grown much like soybeans, Gallagher says. A farmer in Lewes, Del., planted 2.5 acres of the crop, using sorghum plates in a conventional corn planter. The spherical seeds are similar in size to wheat kernels. Weeds took over the plot the first year and it had to be replanted the following spring. "We didn't irrigate it with salt water," Gallagher explains with a chuckle. "Salt water kills the weeds." In the first year, a single shoot per plant crown emerged. "In the second year we've gotten four to seven stems that come up per crown," he says. "By July it was a solid field with no rows visible." One plant in a small research plot, which was dubbed Fat Boy, developed 44 stems, demonstrating the crop's potential for higher yields. The Delaware researchers don't know how long the perennial plant can thrive in a large plot, but the preliminary small-plot work indicates that a 10-year life span is possible. While seed heads don't shatter readily, there may be just enough shattering for the plant to reseed itself and maintain a stand, Gallagher says.

Seashore mallow can grow to about 5 feet tall under fresh-water conditions and 2 feet in salt water. The shorter plants are more like soybeans, which is an important consideration for farmers who want to use their existing equipment to plant and harvest the crop, Gallagher says.

Dry conditions during the growing season allowed the researchers to observe the crop's drought tolerance. "We had about 8 inches of rain in the 20-some weeks until [harvest]," he recalls. The seashore mallow grew quite vigorously while nearby dryland corn yields suffered. The perennial plant's three-eighths inch diameter roots burrow down more than 30 inches into the soil to draw on soil moisture, which gives it an advantage over more shallow-rooted annuals, Gallagher explains.

The 2.5 acre seashore mallow plot was harvested in late September and yielded about 13 bushels per acre. "Had our plot been [in an area] where we could have used salt water for irrigation the yield would have been closer to 20," Gallagher says. Dryland soybean crops in the area are expected to average 24 bushels per acre. "Had the nearby soybeans been irrigated with salt water the yield would have been close to zero," he says. "I'm always apologetic about the yield, but my wife reminds me that 20 bushels [of seashore mallow] is infinitely better than no yield for soybeans on salt." Yet, the economics have to be favorable to get farmers to accept it as a crop, he adds. A comparison of the oil content of seashore mallow and other oilseeds puts the crops on a more even playing field. Initial analysis shows that seashore mallow produces 15 percent to 20 percent oil compared with soybeans at 18 percent to 20 percent and cottonseed at 18 percent. The fatty acid composition is similar to that of cottonseed oil and the meal yields 20 percent protein and 5 percent gum. The woody stems may also have the potential as a feedstock for cellulosic ethanol. Seashore mallow has been collected from 14 other locations in the Southeast, which show promising variations that will be useful in a breeding program, he adds.

Exploring Commercialization
Gallagher is putting together a multi-state team and applying for funding from the USDA. The team needs to raise $1 million, including the university's match, to conduct studies during the next two years and move their research to commercial scale. The team is made up of a chicken producer who will analyze the meal in feed rations, a soybean crusher who will assess oil extraction methods, biodiesel producers who will evaluate the oil, and farmers in Delaware, Maryland and South Carolina who will conduct farm-scale production trials. Other cooperators include Delaware's Geological Survey and the Corporation for Economic Opportunity. James, who serves as chair of the biofeedstock committee for the South Carolina Biomass Council, also invited North Carolina cooperators to join the project.

James envisions seashore mallow will serve as one of several feedstocks for small-scale biodiesel plants. "Unlike ethanol, biodiesel is a fuel that can be made in smaller batches," he says. Big refineries make sense in the Midwest where there are huge acreages of soybeans and corn. "In other parts of the country, we aren't going to have access to huge areas of contiguous crops," James says. "We'll have to have biodiesel technology that can use multiple feedstocks."

One question that needs to be answered is: How much salt-impacted land is there along the nation's coastline? Gallagher assumed the information would be readily available. "It was shocking to me when I tried to come up with the numbers," Gallagher says. "We have projections for a meter rise in tides, but if we go to find out what's being affected the best we can do is go to the county agents and get their estimates." One county in Maryland estimates 3,000 acres have been impacted by the salt water and another county reported 500 acres, he says. The county extension agents get their information from farmers who come to them wondering what they can grow on a field where salt-tolerant alfalfa has died out. "I see this as a very interesting opportunity," James says. "Part of our research is to get more accurate estimates of the acreage being impacted. One of our challenges is to learn where those locations are and how much there is."

Future of Saline Agriculture
Dennis Bushnell a chief scientist at NASA's Langley Research Center has long advocated halophytes or salt-tolerant plants as a biomass source. "I have been trying to sell halophytes for biomass for more than a decade," he says, "[There was] no interest until oil went to more than $60 a barrel." While seashore mallow is a good prospect, there are 250 halophytes with potential uses, he says. Bushnell points out that 44 percent of the planet's land mass is considered wasteland and about half of that land could be productive if water was available. Many of those areas are close to salt-water sources such as oceans or underground aquifers. Seawater/saline agriculture could significantly address global warming, food and fuel issues. "I have never seen anything (including electronics and information technology) move as rapidly as biofuels," he says.

Susanne Retka Schill is a Biodiesel Magazine staff writer. Reach her at or (701) 746-8385.
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