Water Quality Concerns in Florida Stir up Citrus BMP and Phosphorus Questions

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Sunshine on Lake Okeechobee

Water quality issues and problems with algal blooms are popping up around Florida as the summer heats up.

As blue-green algae makes headlines again this summer, fertilizer from farms and urban sources are again under scrutiny. Last year, the state legislature passed the Clean Waterways Act to address continuing challenges with water quality.

The 111-page bill addresses agriculture, using biosolids as fertilizer, regulation of septic tanks, wastewater treatment systems, enhanced penalties, and other rules. It is part of the governor’s multibillion-dollar plan to improve the state’s water quality.

The BMP (Best Management Practices) Program for agriculture also saw some enhancements. The law requires that BMP manuals be updated more regularly to include current science. The Florida Department of Agriculture and Consumer Services (FDACS) will now be required to collect and keep growers’ nutrient program records, with a particular focus on nitrogen and phosphorus. In the past, records of growers who are enrolled in the BMP Program were reviewed but not collected. Under the new law, growers have to fill out a Nutrient Application Report Form. These forms can be turned over to the Florida Department of Environmental Protection (FDEP). The law also instructs FDACS to have on-site verification visits to farms at least every two years to confirm BMPs are being followed.

Phosphorus Confusion

FDACS inspectors have been on the ground doing these verification visits for several months now. Some citrus growers and vegetable producers are reporting they’ve been notified by FDACS that phosphorus levels are too high.

Kelly Morgan, Center Director of the UF/IFAS Southwest Florida Research and Education Center and Professor of Soil Fertility and Water Management, is on the committee updating the current Citrus BMP manual.

“In the committee process to update the current manual, FDACS is telling me some growers are out of compliance with phosphorus usage, but not so much with nitrogen,” Morgan says. “I have asked the agency how far out they are and what kind of numbers are they reporting, but they can’t tell me per the new law that was passed. The information is only exchanged between the grower and FDACS. FDACS can share that information with FDEP but has not yet, as I understand it.”

The privacy clause in the legislation was meant to protect growers, but it is making it difficult to get a benchmark on phosphorus usage.

“There apparently is nothing in the legislation that instructs what is to happen with the information,” Kelly adds. “OK, you are out of compliance, so does that mean a fine, or what else? Right now, we don’t know what the results are going to be and that has caused a lot of uncertainty out there.”

More Study Needed

Highlands County Citrus Growers Association President Bert Harris III addressed the issue in the association’s May newsletter.

“Concerns about phosphorus were not mentioned at all in the two early (1994 and 2002) BMP Manuals for our area and are barely mentioned in the current BMP because nitrogen leaching into groundwater was the main concern,” he noted. “The current manual simply tells growers to ‘base their phosphorous fertilization rate on soil and/or leaf tissue test results and to keep all lab test results to track changes over time.’ It does not set limits or direct growers to follow any specific UF/IFAS guidelines like it does with nitrogen. It only requires growers to keep records of all nutrient applications that contain nitrogen or phosphorous.”

In the newsletter, Harris calls for more research on the appropriate rates before regulations are imposed. Morgan noted that work will begin on phosphorus rates in an HLB-endemic environment, but it will be some ways off from providing results.

“We have not really looked at phosphorus that closely because we felt like we were using so little of it,” Morgan says. “We started some [HLB-infected] rate studies on nitrogen in 2017 and are getting some really good information from that. But that will take a couple more years before we can really determine if we need to go up on nitrogen recommendations. As for phosphorus, we clearly are going to start working on the area of research as well.”