The storm surge that followed the high winds of Hurricane Irma pushed salty sea water over gardens, crops and fields, depositing sodium and other minerals. Two Cornell University experts – Nina Bassuk and Harold van Es – explain that the potential sea water damage depends on soil composition, rainfall and other factors. Both experts are available for comment.
Nina Bassuk, professor and program leader of the Urban Horticulture Institute at Cornell University, says that time will tell whether the storm surge from Hurricane Irma, which contained salty sea water, significantly damaged agricultural crops, native and ornamental plants.
“Stormwater inundation can have a devastating effect on plants. However, there are many factors that contribute to the severity of damage.
“Salt water directly damages plants by accumulating chloride and sodium ions that can be toxic as they accumulate in plants. They can also create a kind of chemical drought where water in roots can diffuse out into the saltier soil. Both of these effects are damaging.
“Timing is important. If plants are actively growing, these effects will cause greater damage. If crops are at the end of their life cycles, there will probably be less damage. Also, the longer plants experience salt water inundation the greater the toxicity.
“A good thing about salt is that it is readily soluble and will leach out of the soil with successive rains. An important factor here is soil texture. A more porous, fast-draining soil like those in southern Florida will leach the salt faster.
“Another factor is plant adaptation. Many plants have adapted to growing in seaside environments and can withstand occasional salt water inundation. Salt can affect shoots and leaves as well as roots. With severe salt spray deposition on plant buds, they can be killed outright.”
Harold M. van Es, faculty fellow at the Atkinson Center for a Sustainable Future and a professor of soil and water management at Cornell University, says that the salt damage to soil depends on rainfall and soil composition – and the good news is that most of the flooding occurred in areas of high rainfall.
van Es says:
“After the storm, there are two concerns with flooding of seawater in inland areas: the salt itself, and the sodium in the salt. The latter is especially of concern with soils that are high in clay content, making soil aggregates disperse and creating dense layers.
“The good news is that the recent flooding occurred in areas with high rainfall and the salts will wash out of the soil in the next months, especially if the soil is sandy. For loam and clay soils we may see some longer-term impacts. A good way to help mitigate the problem is to apply gypsum or lime to the soil, which helps wash the sodium out and maintain good soil aggregates.”