The Impact to North Carolina and Current Research Efforts
Saltwater Intrusion on the East Coast
The Impact to North Carolina and Current Research Efforts
By Andrea Gibbs
Hyde County is located in the Tidewater region of North Carolina in an area referred to as the Blacklands. This area is known for its rich, dark, highly productive soils. Agriculture is Hyde County’s No. 1 industry, bringing in approximately $88 million annually. Field corn, soybeans, cotton, snap beans, and Irish potatoes are our biggest crops.
While the farmland in Hyde County is extremely productive, it is not free from challenges. Approximately 61% of Hyde County is water, largely due to its proximity to large bodies of water such as the Pamlico Sound and numerous rivers, lakes, etc.
This extensive water coverage plays a significant role in the county’s geography and environmental challenges. Due to the flat topography and the proximity to the sound, a network of canals and drainage systems are needed to effectively farm the land and produce high-yielding crops. This can present a problem when saltwater backs up the drainage ways and onto the farmland during a hurricane or tropical storm.
An Ongoing Issue
Farmers in Hyde County have faced the challenge of saltwater intrusion for generations. This issue poses a direct threat to agriculture, as increased salinity in soil and water can drastically reduce crop yields. When saltwater repeatedly saturates farmland, salts bind to the soil particles.
As the water evaporates or drains, these salts remain and accumulate in the soil. Over time, this buildup disrupts plant growth by preventing crops from absorbing water and nutrients, leading to poor emergence and reduced yields.
Continuous exposure to saltwater can render the soil so barren that even weeds struggle to grow. Land that becomes unprofitable for farming is often sold or enrolled in the Conservation Reserve Program (CRP). Unfortunately, land placed in CRP is frequently planted with pine trees, which eventually die due to ongoing saltwater exposure. CRP programs need to be restructured to better support land affected by saltwater intrusion. Landowners should be incentivized to plant native salt marsh vegetation, which can help maintain a natural barrier between the Sound and productive farmland.
Management of Saltwater Intrusion
Farmers are on the front lines of managing saltwater intru-
“Dr. Gatiboni’s research found that salt-includer soybeans are affected when the soluble salt index (SS-I) is greater than 65, while salt-excluders are impacted when the SS-I is greater than 110.”
sion. Most have already identified problem areas on their land and installed water control structures like floodgates, risers, pumps, and dikes to keep saltwater at bay. They are also diligent about maintaining drainage systems where possible.
Daniel Brinn, Hyde County water and flood control coordinator has said, “We live and die by drainage.”
There are drainage entities of varying size and scope throughout the area: drainage districts, service districts, private incorporated and non-incorporated drainage associations, landowner-producer partnerships, and private projects. These drainage projects benefit both homes and businesses alike. Vital drainage infrastructure includes the following: canals, dikes, culverts, risers, viable outlets, pumps, and tide gates. Ditches and canals are so important in the area that most are named.
Cotton, being the most salt-tolerant crop they grow, has become a key part of the rotation for farms significantly impacted by saltwater intrusion. Farmers have also found that holding water on the land, by placing boards in risers and capturing rainwater after the crop is harvested, can be an effective strategy to restore salt-affected soils.
However, this method isn’t always feasible in all areas af-
ON THE COVER: Alabama Soybean Field by Carla Trantham
fected by saltwater. Allowing land to lie fallow and grow natural vegetation is another approach that has proven helpful in bringing salt-impacted elds back into productive use.
Collaborative Research
Prior to 2018, minimal research had been conducted on saltwater intrusion in North Carolina. at year, East Carolina University (ECU) began collecting data using groundwater loggers, electrical resistivity tomography, and geoprobe drilling. ECU’s research revealed that, in addition to storm surge and wind-driven inundation, saline groundwater is rising through the soil pro le in some areas, impacting farmland not typically a ected by saltwater.
In 2020, North Carolina State University’s Climate Adaptation through Agriculture & Soil Management (CASM) team, led by Dr. Matt Ricker, associate professor in the Crop and Soil Sciences department at NCSU, began conducting research in Hyde County. e CASM team is focused on understanding the e ects of salinity on soil carbon cycles through soil mapping, land use recommendations, and wetland restoration.
Dr. Ricker has been collecting soil samples from both farm elds and marshes to provide farmers with practical solutions and tools for managing saltwater intrusion. One of the team’s key innovations is a eld kit that Extension agents can use to quickly assess soil salinity. is tool will be invaluable to farmers in determining salt levels in the soil a er hurricanes or tropical storms, helping them make informed management decisions for the following year.
Hyde County Extension provides support to growers and landowners by o ering water and soil testing to assess salt levels. I work closely with farmers to identify their needs and research priorities and have collaborated with Extension specialists to plant demonstration plots of salt-tolerant crops. One of those crops is barley, which has shown promise; however, there is currently no market for
barley in our area, but some farmers have used it as a cover
Tim Jett
Mid-South/Delta 901-589-2120
tim.jett@conterraag.com
Robby Frantzis Southeast/East 901-589-2120
robby.frantzis@conterraag.com
Salt-excluder Soybeans
One of the research needs we identified is salt-excluder soybeans, which possess a gene that allows the plant to exclude chloride and prevent stunting in salty soils. The key question is: how much salt can these soybeans tolerate?
In 2021, I worked with several agriculture Extension agents in northeastern North Carolina to evaluate different salt-excluder soybean varieties. In 2023-2024, Dr. Luke Gatiboni, Extension soil fertility specialist and associate professor at NCSU, and his graduate student Anselme Dossou conducted a more extensive evaluation of these varieties. Dr. Gatiboni’s research found that salt-includer soybeans are affected when the soluble salt index (SS-I) is greater than 65, while salt-excluders are impacted when the SS-I is greater than 110.
Looking Forward
This year, Dr. Luke Gatiboni conducted a test in Hyde County to evaluate different gypsum application rates, while Dr. Guy Collins and I are testing a biological product on cotton.
Hyde County has quickly become a center for saltwater intrusion research, with new projects continually being developed. East Carolina University and NC State University recently received SeaGrant funding to further monitor saltwater intrusion and develop a sensor network to alert farmers when water control structures are leaking.
NC State Extension is also planning to explore and evaluate alternative crops, microbial products, and various nutrient applications. As saltwater intrusion becomes an increasingly pressing issue, Hyde County Extension remains committed to finding solutions that will help our farmers continue to thrive for generations to come!
be reached at andrea_gibbs@ncsu.edu.
Andrea Gibbs is the Hyde County Extension agent in North Carolina and may
A tide gate is just one example of the vital drainage infrastructure needed in Hyde County due to saltwater intrusion.
Salt-excluder soybeans possess a gene that allows the plant to exclude chloride and prevent stunting in salty soils.