April is when we turn our focus to fertilizing our gardens and lawns for the first time.
April is when we turn our focus to fertilizing our gardens and lawns for the first time. This is tricky and confusing, as there are many different formulas of fertilizer on the market. Understanding the product label is the crucial first step in using the right formula regarding your needs.
Thankfully, Florida state law requires manufacturers to list fertilizer components on the packaging. On the packaging, one will find a label with the manufacturer’s identification listed. Next, the term “organic” maybe used. This will help in determining how much of the product is synthetic. This is important as organic and synthetic fertilizer affect soil fertility differently. Synthetic fertilizers are often readily available for plant uptake, whereas organic fertilizers are taken up more slowly.
The most important information is found on the area of the label noted as “guaranteed analysis.” Here, you’ll find a series of numbers that refer to macronutrients and their percentages. Often, nitrogen-phosphorous-potassium or N-P-K is shown. This is known as a complete fertilizer because it contains all three macronutrients. The series states the guaranteed laboratory analyzed percentage of the essential macronutrients.
So, how does this work? For example, a 10-10-10 fertilizer will contain 10 percent of each of the three elements as shown in the photo. Therefore, 100 pounds of this fertilizer will contain 30 pounds of N-P-K (10-10-10). The 70 pounds remaining consists of soil conditioners and other fillers that help evenly disperse the fertilizer. Trace micronutrients may also be found within the 70 pounds. These elements include calcium, magnesium, iron, zinc, copper and others. There will be a note at the bottom of the label if there is a significant amount of trace micronutrients.
Above all, nitrogen is most influential element for your garden or lawn. There are many chemical compositions of nitrogen. Some examples of nitrogen found on labels are nitrate nitrogen, ammoniacal nitrogen, water soluble organic nitrogen, urea nitrogen, and water insoluble nitrogen. Plants use nitrate, water soluble organic, and urea nitrogen quickly. These formulated nitrogen compounds will work well in a vegetable garden. However, these forms of nitrogen don’t last long in our environment. The fertilizer will be taken up quickly by plants and can be rapidly leached out of the soil by rain and irrigation water. Ammoniacal and water insoluble nitrogen will last much longer in our sandy soils. Slow or controlled release nutrients, especially in the case of nitrogen, will be denoted on the label as a footnote. This will be shown as a percentage of the actual nutrient.
Be sure to check the label for chlorine. There may be a statement regarding the maximum amount. Excess chlorine can damage vegetable crops and some ornamental landscape plants. Small amounts of this fertilizer are beneficial.
Disseminating fertilizer information and application rates is challenging. This article is designed to clarify some of the basic points of reading a fertilizer label. To obtain recommendations on the proper fertilizer and application for your garden or lawn, please contact the Gulf County Extension Office at 639-3200 for more information.
Supporting information for this article can be found in the UF/IFAS EDIS publication: “The Florida Fertilizer Label” by T. W. Shaddox, Assistant Professor; UF/IFAS Fort Lauderdale Research and Education Center: http://edis.ifas.ufl.edu/pdffiles/SS/SS17000.pdf
UF/IFAS Extension is an Equal Opportunity Institution.