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Fertilization is a key element when enhancing your landscape's overall health. A soil test is the best way to assess your landscape's current levels of nutrients.
Vital Elements
All plants need certain chemical elements for appropriate appearance and growth. Of these nutrients, 17 are known to be vital elements. All vital elements except hydrogen, carbon, and oxygen are acquired from the soil and drawn up by plant roots. If there are insufficient nutrients in the soil, turfgrass quality and growth may be limited. However, vital elements can be added to the soil through fertilizer applications.
Turfgrasses need the macronutrients nitrogen (N), phosphorus (P), and potassium (K) in the highest quantities. Magnesium (Mg), calcium (Ca), and sulfur (S) are needed in lesser quantities. The micronutrients iron (Fe), zinc (Zn), manganese (Mn), copper (Cu), molybdenum (Mo), boron (B), and chlorine (Cl) are needed in very small quantities. Micronutrients have the same importance as macronutrients but are needed in much less quantities.
Types of Fertilizers
Fertilizers are classified by brand name and analysis. Numerous common commercial fertilizers are recognized by their grade, like 10-10-10, 16-4-8, or 6-6-6. A whole fertilizer consists of N, P, and K. The numbers indicate the percentage of every nutrient. For instance, a 16-4-8 fertilizer consists of 16% total nitrogen, 4% available phosphorus indicated as P2O5, and 8% soluble potassium indicated as K2O.
Therefore, a 100-pound bag of 16-4-8 would consist of 16 pounds of nitrogen, 4 pounds of phosphate, and 8 pounds of potassium. The three constituents, N, P, and K, are known as the primary plant foods; if all three are present, the fertilizer is called a complete fertilizer. Fertilizers, like 16-4-8, 10-10-10, 12-4-8, and 6-6-6, are complete fertilizers that are commonly used. Generally, turfgrass fertilizers do not have phosphorus, thus a standard turfgrass fertilizer can be a 15-0-15. Except for the primary constituents (N, P, and K), the fertilizer may consist of secondary elements. The nutrients indicated as secondary on the label may include Ca, S, Mg, Mn, Fe, Cu, Zn, and Mo.
The primary and secondary elements are given on the fertilizer label. The label also has information about the materials from which the fertilizer has been designed. This information appears under the "derived from" statement.
For Florida turfgrasses, the best annual fertilization program often includes a combination of single or two applications of several nutrient fertilization and a few supplemental applications of an N fertilizer. Nitrogen fertilization is usually dependent on the favored growth rate and the kind of turfgrass being grown.
The way fertilization was done in the past and because of the basic nature of some Florida soils, P fertilization is not always necessary. You should rely on the latest soil test to know if phosphorus is needed for optimal turfgrass growth. If your soil test shows a sufficient level of determinable soil P, select a fertilizer blend that does not comprise P as a supplied nutrient. That blend would be expressed as X-0-X, like 15-0-15. Excess P application can lead to enhancement of the P status of leachate or run-off waters.
Fertilizer Application
Most fertilizers are applied at a rate controlled by the amount and type of nitrogen present in the material. Nitrogen is the nutrient maximum used by turfgrass and is usually the element that burns it if applied excessively.
In the past, it was a traditional practice to recommend applying 1 lb of true nitrogen per 1000 sq ft of turfgrass. It is now suggested that not more than 0.7 lb of the nitrogen should be in soluble form in the application. Thus, to make an application of 1 lb of true nitrogen per 1000 sq ft of turfgrass one would require to use a blended fertilizer product comprising not more than 70% of the complete N in soluble form with the remaining nitrogen arising from a slow-release N source.
The latest revision of the Florida Urban Turfgrass Fertilization Rule specifies that not more than 2 lbs of N per 1000 sq ft in one application may be applied in the summer and spring and not more than 1 lb of N per 1000 sq ft in one application may be developed during the fall.
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