GAINESVILLE, Fla -- Florida’s strawberry producers must protect their multimillion-dollar annual crop from freeze damage. Traditional methods involve constant spraying of water during a cold snap. Growers are looking for ways to use less water, yet produce the same amount of crop.
New University of Florida research shows growers can keep using both their current sprinkler spacing and low pressure or enhanced real-time irrigation control to save water – and they can produce the same strawberry crop yield during mild freezes.
“It’s a step in the right direction,” said Michael Dukes, a UF/IFAS professor of agricultural and biological engineering and the lead author on the study. The improvement? An automated control treatment that used real-time dew point measurements – rather than temperatures — to turn the system on and off, he said.
Growers typically turn on their sprinklers when temperatures reach 1.1 degrees centigrade, or around 34 degrees Fahrenheit, and keep them on until the sun melts the ice. During the years of the study, temperatures dipped below 1.1 degrees centigrade for 50 hours. In each of the two years prior to the study, freezing periods were longer, with about 150-200 hours below that temperature.
In the study, scientists used growers’ methods with real-time dew point measurement to control the system, and then researchers used grower spacing with low water pressure.
The enhanced control system saved 91,000 gallons in one year, 700,000 gallons the next, Dukes said. The second year is more representative of what growers can expect, he said.
“By reducing water use, growers also can reduce fertilizer leaching, as well as prevent fungi diseases, meaning less pesticides,” said Maria Zamora, who conducted the experiment for her master’s thesis. “That, in turn, can be translated into a reduction of aquifer pollution.”
The findings of the study, funded by the Southwest Florida Water Management District, should help Florida strawberry growers, who are located mainly in Hillsborough County. Florida is second only to California in annual strawberry production. In 2013, Florida’s strawberry harvest brought in $267 million, according to the U.S. Department of Agriculture.
Florida strawberry growers grapple with a short growing season and cold conditions.
While using less ground water helps the environment, the study did not cover hard freezes because the temperatures did not get that cold during the three growing seasons in the experiment.
So the next step would be to see if a better irrigation system can save water and produce the same strawberry yield during a hard freeze, Dukes said.
Dukes supervised Zamora’s study. Results of the study appear in the current issue of the Journal of Irrigation and Drainage Engineering.
The 2009-10 and 2010-11 winters were the coldest in 10 years for strawberry growers. Zamora, now a doctoral student, conducted the experiment in the winters of 2011-12 and 2012-13 at the UF/IFAS Plant Science Research and Education Unit near Citra. She looked at how spacing of irrigation systems and water pressure would impact strawberry yield protection under cold conditions.
Caption: Strawberry growers traditionally use water to protect their crops during cold snaps. New UF/IFAS research shows ways the growers can cut water use, which helps the environment and saves money.