You can judge fertilizer by appearance. Fortunately, state law requires each fertilizer label to include specific content facts. However, these can be confusing.
To obtain the proper types of fertilizers for various applications, you must understand the label. At the top you’ll find the identification of the manufacturer or distributor. Of course, this doesn’t tell how well the fertilizer will help your lawn, ornamentals, or vegetables.
Next, if the term “organic” is used, these will be a statement identifying the type of material, as well as how much is natural, and how much is synthetic. This is an important indication of how the fertilizer will react in your soil. For example, natural, natural organic nitrogen is released slowly. A fertilizer containing a high percentage of this material would be good for lawns, helping them stay green, without causing spurt s of extra fast growth.
The key information is found in the guaranteed analysis section of the label. A series of numbers, such as 8-8-8 or 10-10-10, tell you which, and how much, of the primary plant nutrients the fertilizer contains. That is, the numbers show the guaranteed amount of nitrogen, phosphorus, and potassium. For example, a fertilizer labeled 10-10-10 contains ten percent
nitrogen, ten percent phosphorous, and ten percent potassium. Thus, a hundred pounds of this analysis contain 30 pounds of plant food. The other 70 pounds is accounted for by conditioners and fillers, require for even spreading. These may include some incidental trace elements. If the fertilizer contains significant amounts of secondary plant foods, such as calcium, magnesium, copper and other, they will be listed near the bottom of the tag.
The most difficult part of the label to understand is the information listed right after the total nitrogen figure, in the guaranteed analysis section. In addition to the total amount, the label gives percentages of each of several types of nitrogen in the mix. This tells you a lot about how the fertilizer works.
You’ll see the terms nitrate nitrogen, ammoniacal nitrogen, water soluble organic nitrogen, urea nitrogen, and water insoluble nitrogen. Plants use nitrate, water soluble organic, and urea nitrogen fairly quickly. They might work well in a vegetable garden. But, they won’t last very long, because they’re rapidly leached out of the soil by rain and irrigation water. On the other hand, ammoniacal and water insoluble nitrogen will last longer in sandy Florida soils.
Following the basic analysis, is a statement of the maximum amount of chlorine the fertilizer contains. Excess chlorine may be injurious to certain plants, both vegetables and ornamentals species. Small amounts can be beneficial under some condition.
Unfortunately, I can’t fully explain anything this complicated in one short article. I hope I’ve clarified a few of the basic points. To obtain the proper fertilizer for your specific vegetable and ornamental gardening needs, you must understand the information on fertilizer labels when in doubt; we suggest you check with your County Extension Agent.
Fall Vegetable Gardening Seminars
The Gulf County Extension Service will sponsor a fall gardening interactive video series. The following subjects will be covered in a three night Series:
Sept. 9, Expectations, planning, and site preparations;
Sept. 16, Tips to use whether you are starting with seeds or transplants:
Sept. 23, Cool season crops such as lettuce, broccoli, cabbage, chard, strawberries, onions, potatoes and carrots.
For more information contact your local Extension Office at 639-3200.