Survey of Fertilizer Products in Lee County, Florida
In recent years, many municipalities in Florida have taken steps to reduce surface water runoff and leaching of fertilizers containing nitrogen and phosphorus from residential neighborhoods and commercial centers. The assertion is that improper landscaping and excess fertilization practices have the potential to impair fresh water bodies, estuaries, and bays. Municipalities have enacted ordinances that prohibit the application of fertilizers containing nitrogen and phosphorus during the rainy season, usually from June 1 through September 30. Some of the ordinances require that the nitrogen component of the fertilizer contain no less than 50% slow-release nitrogen (SRN). In almost all cases, the ordinances do not restrict the nitrogen or phosphorus contents or formulations of fertilizers being sold at any time of the year.
The purpose of this survey was to determine the types of fertilizers being sold in Lee County, Florida. The survey examined the nitrogen and phosphorus contents of fertilizers and the percentage of SRN in the analysis. This survey was conducted in July and August of 2012 at the garden sections of three home improvement stores and three independent garden centers. The three home improvement stores represented three separate national chain stores.
Survey Results: Fertilizers of 199 different types were sold in six stores representing three national chains and three independent stores (Table 1). In order of decreasing numbers, the following types of fertilizers for several plant categories were on sale in Lee County; turfs/lawns 45 (22.61 %); palms 13 (6.5 %); flowering plants 14 (7.03% ); bloom pushers 12
(6.03% ); fruit trees including citrus and avocados 11 (5.52%); vegetables including tomatoes 8 (4.02%) and roses 6 (3.02%) (Figure 1, Table 2). Fertilizers for other but smaller plant categories were also on sales including those for orchids and cacti.
Five fertilizers (2.51%) were sold as products to raise pH (lime) and four (2.01%) were sold to lower pH (acidifier) (Table 1). Forty fertilizers (20.10%) included the word “organic,” “natural” or labeled having animal and plant byproducts such as fish emulsion, blood meal, cottonseed meal and seaweed. In descending order, the following plant nutrients were highlighted on
the labels, Iron 11 (5.52%); micronutrients 6 (3.01%), Magnesium as Magnesium Sulfate 5 (2.51%); Manganese as Manganese Sulfate 4 (2.01%); potassium 3 (1.51%); phosphorus 2 (1.01%) and caltrate 1 (0.50, %). Forty-four (22.11%) excluded phosphorus while including nitrogen and 10 (5.02 %) excluded nitrogen while including phosphorus.
Many local ordinances prohibited the applications of nitrogen and phosphorus containing fertilizers during the rainy season, mainly from June through September. The term “Summer Blend” has no legal standing but is generally regarded as a fertilizer containing no nitrogen and phosphorus and is specifically labeled as such. It is formulated for applications during
the rainy season when nitrogen and phosphorus applications are mainly prohibited. Only 2 (%) analyses surveyed were labeled as summer safe (Table 1). Other fertilizers, containing no nitrogen and phosphorus, and not labeled as summer blend, can be used during the summer without contradicting the letter of the ordinance. These include Manganese sulfate
(0-0-0-32Mn), magnesium sulfate (0-0-0-16Mg), soil acidifiers (0-0-0-90S) and murate of potash (0-0-60).
Many ordinances state that fertilizers applied to turf and/or landscape plants shall contain no less than fifty percent (50%) slow release nitrogen per guaranteed analysis label. The survey found the majority of analysis, contained less than 50% SRN 79 (39.70%). Fifty-eight (29.14%) contained 50 percent or more SRN; Thirty-seven (18.60%) contained no nitrogen
and 25 (12.56%) did not indicate SRN content. Although not indicated in this survey, many of the fertilizers sold having 50% or more SRN were small specialized packs not meant for general applications to turf or landscapes. Thus, for bulk applications of fertilizers, the consumer has few choices for ordinance compliance using SRN fertilizers.
To view the complete survey, view the PDF file linked below