Florida scientists will study how farm pesticides called fumigants affect the soil in Hillsborough County, and the research results will apply across the state.
At least a month before planting crops, Florida farmers fumigate their sandy soils to manage diseases, pests and weeds. They apply the pesticide to the bottom of raised beds.
Here’s how Gary Vallad, a professor of plant pathology at University of Florida/IFAS, described raised beds:
“Think of it as almost like making a sandcastle at the beach … you pile up the sand and you pack it down into a bed,” he said.
The beds then get covered with plastic to hold in the fumigants and treat the soil.
“The fumigant itself breaks down and part of it is degraded by soil microbial communities,” said Vallad. “It dissipates well before we ever put a crop in the ground… but the impacts of that fumigation last the entire season.”
There’s still a lot left to learn about soil, though. So now, Vallad and three of his colleagues at UF’s Gulf Coast Research and Education Center, just south of Tampa, want to know how this process impacts soil health in the long run.
"If certain fumigants have certain impacts that are either beneficial or not beneficial, you know, maybe we can fine tune those practices to minimize that impact in the future," he said.
His team is looking for effects in soils that are similar, in theory, to the effects in people when taking antibiotics to combat a bacterial infection — the medication also kills the good bacteria the human body needs to fight the infection in the first place.
“We're trying to target just the bad actors in the soil, if you will, but we do know it has broader consequences for the soil itself … we just really don't understand it fully,” said Vallad.
He and his colleagues will experiment within Hillsborough County strawberry and tomato farms over the next four years thanks to an $850,000 grant from the U.S. Department of Agriculture National Institute of Food and Agriculture.
"Hillsborough County is an important place for agriculture in the state of Florida. So, I would say we're just on the northern tip of some of the largest vegetable production area in the southeast,” Vallad said. “Also, we grow a great deal of strawberries in the area as well as vegetables, so it's very important to our economy."
The scientists will conduct standard fumigation practices as any commercial grower might, and take soil samples before and after the application throughout the growing seasons. Using genomic tools, they plan to also get a profile of soil “communities.”
“We can … collect DNA from the soil, and actually use that to generate almost like a fingerprint, kind of a profile of who's there in that soil and also get an idea of their relative abundance,” said Vallad.
The goal is to give Florida farmers some data and feedback about these practices, he said.
“What we're hoping is by understanding the impact of fumigation on certain soil processes, we can find better ways to manage or to improve on the way we manage our soils,” said Vallad. “I guess it really comes down to agriculture security in Florida … to keep it sustained and passing it along to the next generation.”
