By Yuncong Li, Haimanote Bayabil and Jonathan Crane, University of Florida
A new report that projects sea levels will rise 10 to 12 inches — and much more in some parts of Florida — by 2050 should sound an alarm in our state.
The National Oceanic and Atmospheric Administration, which authored the report, predicts moderate flooding, from tide, wind and storm-driven extreme water levels, will happen 10 times more often than it does now.
Such talk leads many to think about the threat rising seas pose to waterfront homes, coastal businesses and recreation spots. Much less attention is focused on agricultural areas and the impact of saltwater intrusion on crops – and that is unfortunate.
To be sure, sea-level rise is a complex problem, with multiple and interconnected driving factors requiring many approaches and dedicated effort. But we have the opportunity to adapt and adopt measures now that may help protect our agricultural operations.
Florida produces more than 300 commodities, from tomatoes to citrus to strawberries, which generated roughly $7.4 billion in cash receipts in 2020. The state has 9.7 million acres of farmland and, along with other southeastern states, is expected to play an increasing role as a food producer as climate change affects where, when and how crops can be successfully grown.
But we must act now to reduce saltwater intrusion, which affects soil, surface and groundwater and plant viability, given that many farmlands in Florida are near the coastline. For example, in parts of the South Dade Agricultural area, which as of 2017 had nearly 71,000 acres being farmed, some elevations are less than 3 feet above sea level. Other examples of agricultural land at risk include areas in Palm Beach, Martin, St. Lucie, Lee, Manatee and Sarasota counties.
Even a slight increase in saltwater intrusion into Florida’s aquifers could have major repercussions on the availability of fresh water for drinking and agricultural purposes. Consider that in South Florida, 48% of groundwater withdrawals are for the public water supply and 34% for agricultural irrigation.
While we may not be able to stop sea-level rise quickly, there are measures that may reduce some effects on agricultural productivity and farmers’ livelihoods.
Florida’s rising stature as a food producer necessitates taking this issue seriously and adopting both short-term mitigation measures and long-term adaptations, such as investing in and breeding salt-tolerant crops and working with agricultural engineers, water managers and climate scientists to reduce saltwater intrusion.
Short-term management practices could be implemented at farm and field levels. One approach is improving irrigation efficiency to reduce water use rates and volumes needed to grow crops. Better irrigation efficiency also is critical to reduce groundwater pumping and salt buildup in the soil. Alternative water sources for irrigation, such as reclaimed water, could be used to offset freshwater demand.
Another short-term potential measure is to flush salt-affected soils with freshwater, which temporarily keeps soil salinity low. However, while this method can be done relatively quickly, it is limited by the availability of freshwater, must be repeated periodically and has the potential for contamination of groundwater.
In addition, gypsum, biochar and compost are soil amendments that could help counter negative effects of salt-soaked soil, as can the use of salt-tolerant cover crops. And establishing and growing some crops on raised beds may elevate their root systems, allowing them to avoid saline conditions found at lower soil depths, though this approach requires additional investment of money, time and labor.
Long-term management practices, such as breeding saline tolerant crops, take funding and dedication over a long period for development and adoption and will depend on growers’ willingness to adopt new cultivars.
Almost all crops grown in South Florida are sensitive to high salinity and flooding, such as snap beans, strawberries, blueberries, squash, tomatoes, avocados and papaya. Saline-stressed plants have reduced nutrient uptake and don’t flower and fruit well, which also means they are more prone to disease and pests.
There are a very few plants with limited tolerance to salinity: coconuts, sapodilla and tamarind. And there are some that can withstand periodic flooding, such as coconut, guava, jujube and mango. But we have to breed salt and flood-resistant cultivars of major commodities.
Changing our agricultural practices in such fundamental ways will require ongoing attention and funding over the coming years, especially given that rising seas are already steadily encroaching on our communities. It also will require support and involvement of the state, given growers’ thin operating margins and the cost to implement most management practices.
We are in a race against time to better understand the mechanisms and negative effects of sea-level rise and saltwater intrusion on freshwater resources, soil health, crops and our ability to play a role as a major food producer.
Coming up with the best management practices to mitigate these impacts will take time and funding and should be a priority to safeguard food and water resources.
Yuncong Li is a professor of soil and water sciences, Tropical Research and Education Center at the University of Florida. Haimanote Bayabil is an assistant professor of water resources, Tropical Research and Education Center at the University of Florida. Jonathan Crane is a professor of horticulture, Tropical Research & Education Center at the University of Florida.