Fertilizers containing nitrogen and phosphorus have been banned on Sanibel Island, Florida, at least temporarily. According to a story published on the Captiva/Sanibel.com website, the ban came with the arrival of rainy season.
From July 1 through Sept. 30, a city ordinance prohibits the application of fertilizers containing those ingredients. Products containing only secondary nutrients or micronutrients such as magnesium and iron may be applied throughout the blackout period and are the only exceptions.
“The goal is to reduce nutrient pollution to our local waters,” Holly Milbrandt, deputy director of Sanibel's Natural Resources Department, says in the story. “They (nitrogen and phosphorous) are the same two nutrients that cause algae blooms in local waterways. It all comes back to the water quality issue.”
She added that grass tends to grow “just fine” without fertilizer during rainy season. “So using it is sort of doing what Mother Nature is already doing by itself,” Milbrandt was quoted as saying.
In the meantime, landscapers can use so-called “summer blends,” fertilizer products made with alternative components like iron, magnesium and potassium that fall under the exemption and are permitted for year-round use on Sanibel. “They benefit plants, do not impact water quality and can still be applied,” Milbrandt says in the story.
The blackout rule is even more stringent for property within 25 feet of a body of water. There, products containing nitrogen and phosphorous can never be used, no matter what time of year it is.
The city's ordinance stems from the fact that Sanibel gets heavy amounts of rainfall in the summer. In the story, Milbrandt explains that the nutrients in fertilizers can quickly get washed off into storm drains and local waterways. “For us in the summertime, heavy rains are always imminent,” the article quotes her as saying.
Milbrandt noted that similar blackout periods are not uncommon for coastal municipalities. Lee County has one that runs from June to September, one month longer than Sanibel’s.
Outside of the blackout period, from Oct. 1 to June 30, the ordinance requires the use of slow release nitrogen and low phosphorus fertilizers. They must have 20 percent or less of nitrogen, of which 50 percent must be slow release, and 2 percent or less of phosphorus. “A lot of Florida soils are very high in phosphorus already,” Milbrandt is reported to have said.
The city recommends that property owners have their soil tested to better understand its composition and what is does and does not need. Going fertilizer-free is also an option.
Some tips for doing so include embracing native plants, planting the right plants in the right place and understanding which areas in a landscape get sun and so forth. One can also leave grass clippings on the ground after mowing and irrigate with reclaimed water. “We know our reuse water has nitrogen and phosphorous in it,” Milbrandt reportedly said.