Fertilizer on hiatus

A worker spreads fertilizer at the Venice Golf and Country Club.

With Saturday the effective seasonal deadline for yard fertilization in Southwest Florida, many homeowners might wonder if the restrictions imposed by local fertilizer ordinances are really necessary.

A recent study by the Charlotte Harbor National Estuary Program should reassure them: By obeying limits on fertilizer use, they've helped make a dramatic improvement in the health of bays, rivers and other waterways critical to our economy and environment.

Lisa Beever, director of the Charlotte Harbor NEP, reported May 21 on a study she conducted on the impact of fertilizer ordinances passed by local governments -- including Sarasota, Charlotte and Lee counties -- since 2007.

The Charlotte Harbor estuarine system makes for a comprehensive and critical study area. It extends from Venice to Bonita Springs on the Gulf, and inland as far north as Winter Haven in Polk County. It covers about 4,500 square miles and includes the Peace, Myakka and Caloosahatchee river basins and coastal waters such as Lemon and Estero bays as well as Charlotte Harbor.

Using data from throughout the system, Beever compared the readings of nitrogen and phosphorus -- two major ingredients in most fertilizers -- in 2005-2006 to those in 2010-2011. The first two-year period came before the adoption of most fertilizer ordinances, and the second came after. Both periods had similar total rainfall.

Between the two time periods, Beever found, on average, a 21 percent reduction of total nitrogen and a 27 percent reduction of total phosphorus.

Given the size of the Charlotte Harbor system and the relatively recent adoption of fertilizer ordinances, Beever told us, the reductions "are significant."

Ordinances get the credit

Beever credits the reductions almost completely to the ordinances. No major expansion of central sewer systems occurred in the study area between the two time periods, and any storm-water projects to reduce runoff to the water bodies were too few and too dispersed to make much of a difference.

Read the rest here:
Fertilizer on hiatus