By adam thomas
College of Agriculture
and Natural Resources
For Delaware farms near the coast or close to brackish waters, dry seasons can hit hard in two ways. Not only are the farms deprived of fresh rainwater to help boost their crop yields, they also face the threat of farmland salinization.
Farmland salinization is exactly as it sounds: salt water seeps into farmland soils and spoils crops, and with sea levels rising in the First State, the problem doesn’t appear to be going away any time soon.
“There’s probably acres that get flooded every year, so that’s a continual challenge,” says Cory Whaley, a Cooperative Extension agent at UD. “The salt levels just get so high that it becomes, in most cases, impossible to grow our normal grain crops, corn and soybeans.”
That’s a big problem for Delaware farmers, as the two most popular crops grown in the state—corn and soybeans—are sensitive to salt, although
Whaley does note that corn is slightly more salt tolerant than soybeans.
In 2008, Whaley saw the effects of farmland salinization firsthand in
areas around the Delaware Bay. A high tidal surge impacted thousands of acres, resulting in significant crop loss.
Not only did the tidal surge kill the crops for that season, but it also had lingering effects for future yields.
“The frustrating part is that it destroyed the crop that was there, but if you come back and replant, your chances of having salt injury on the replant is there, so it’s almost like you’re leaving it barren,” Whaley says, noting that this problem is largely dependent upon how long the salt water sat on the cropland and how much salt got absorbed into the soil.
When it comes to dry seasons, Whaley says the threat of farmland salinization is especially prevalent because “you’re relying on rainfall or irrigation to leach out the excess salts. So the more precipitation on the ground, the more salt you’re going to leach out.”
When there is big tidal flooding, like Whaley encountered in 2008, he says an option farmers have to deal with farmland salinization is to moldboard plow. This practice allows for a plow to go 10–12 inches into the earth and turn the soil over, taking the topsoil and putting it on the bottom. This helps the crop get going by having fresh soil on top and allowing the rain to leach out the salt from the bottom of the crop.
Whaley said that another thing they noticed was that when they did soil testing for salt concentrations, they found that as the salt water receded, the salt levels were higher the closer they got to where the water initially came up.
For farmers that grow in areas where salt levels are the highest, Whaley recommends growing crops that can handle higher salt levels such as wheat, barley or certain species of grass for hay.