Photo courtesy of UF/IFAS
By Clint Thompson
Controlled-release fertilizers remain an effective and efficient way for North Florida watermelon producers to prevent leaching, specifically during the first few weeks of the season.
Bob Hochmuth, University of Florida Institute of Food and Agricultural Sciences (UF/IFAS) Regional Specialized Extension agent in Live Oak, Florida, has researched the system’s effectiveness. He spoke about control-released fertilizers at this year’s Suwanee Valley Watermelon Institute meeting on Dec. 5.
“It affords us a very important factor and that’s protecting the fertilizer that’s normally put under the plastic in the bed; it affords us a little more protection from leaching. Without some way of protecting that fertilizer under the bed, there is concern of being able to protect it; so the polymer-coated fertilizers do help,” Hochmuth said.
“The coating does not allow the fertilizer that’s trapped inside that coating to be leached. If you get a heavy rain event or if you over-irrigate early in the season with a conventional unprotected fertilizer, then you’re more likely to lose some of that. The polymer-coated fertilizers help, especially on the front end when we’re really vulnerable to losing some of that fertilizer.”
Early-Season Vulnerability
He said growers are most vulnerable early in the season because there’s not very much of a root system in place.
“The way the process would go is we would put out the conventional fertilizer, two, three, maybe four weeks ahead of time. There’s no root system there to pick it up until we plant, and even when we plant, it takes a little bit of time before that root system is there to pick it up. That’s the period of time where we have the most vulnerability to losing nitrogen,” Hochmuth said. “After the root system gets established after 30, 40, 50, 60 days, then it’s a lot easier to manage because the crop will pick a lot of that up. But early in the season that root system is just not there.”
Hochmuth estimated that there were 1,000 acres last year that implemented polymer coated fertilizers. It is a more expensive process, but there is cost-share funding available from the state.
Controlled-release fertilizer reduces leaching because the nitrogen is released over a period of time. It is present when growers need it the most at different points in the season. Producers who utilize polymer coated fertilizers can dictate how long they want to wait before releasing it in the soil. One layer of coating and 80% of it is released in 45 days. The more coating that is applied makes it last longer in the soil.