MRC Study Shows Success of Strong Fertilizer Ordinances

Dr. Leesa Souto and colleagues recently published a peer-review scientific journal article evaluating the effectiveness of residential fertilizer ordinances on Florida’s west coast. The study demonstrates that fertilizer ordinance education successfully changed homeowner behavior and reduced pollutant loads in the Tampa Bay Area.

The research collected residential awareness, knowledge and behavior data as well as stormwater and pond water nitrogen concentrations in three counties with varying fertilizer ordinances. In the county with the strongest fertilizer ordinance, residents were more aware of the ordinance and they were applying fertilizer less frequently. In the county with the least restrictive ordinance, residents were applying fertilizer more frequently and nitrogen loads were highest.

This research helped Tampa Bay justify a higher TMDL credit for Pinellas County than the credit other municipalities receive for adopting a fertilizer ordinance. The Pinellas County ordinance has a summer retail sales restriction that requires that fertilizer retail stores remove noncompliant products from the shelves during the summer season. Manatee County has an ordinance similar to Brevard County’s with the summer application restriction. Hillsborough County has the state’s model ordinance that has no summer restriction. The Pinellas County ordinance with the sales restriction has been pre-empted by the state legislature. This makes Pinellas County the strongest fertilizer ordinance in the state (and according to this research, the most effective)!

Every county along the lagoon and nearly every city has adopted a residential turf-grass fertilizer ordinance similar to Manatee County. The lagoon ordinances include the following things, but retail stores are not required to remove illegal products from the shelves during the restricted season. That ability has been pre-empted by the state in response to the pressure from agri-chemical interests.

1. No nitrogen can be applied to the lawn during the rainy season from June 1–September 30
2. When fertilizing with nitrogen outside the rainy season, you must apply at least 50% slow-release N. For a list of compliant fertilizer products click here.
3. Do not apply phosphorus to the lawn, unless a soil test confirms the need for it.
4. Do not apply any fertilizer within 10’ of a water body (the set-back distance varies by city or county, so check your local ordinance here.

The complete research paper, Forging linkages between social drivers and ecological processes in the residential landscape, is available here.