Fertilizer analysis of this bag: 5% nitrogen, 10% phosphorus, and 15% potassium |
Fertilizers are frequently applied to plant material as a supplement
because the soil does not supply enough of the needed nutrients. Many types of
fertilizers exist, and not all are created equal. By knowing some basics about
fertilizers and the various types, you can choose one that will be the most
beneficial.
Before
applying fertilizer, consider having your soil tested through Gwinnett County
Extension. The results will show the nutrient status and the relative acidity
of the soil (pH) through soil testing. Applying fertilizer without a soil test
can result in the application of too much or too little lime and fertilizer
required for optimum growth
Plants
require several nutrients for sustenance. Nitrogen, phosphorus, and potassium
are the ones they need in the highest quantity whereas sulfur, magnesium and
calcium are needed in lesser amounts. Some nutrients, such as zinc, iron, and
manganese, are only required in small quantities.
The
numbers on the fertilizer bags are labeled with three numbers that indicate the
guaranteed analysis, or the fertilizer grade. These three numbers give the
percentage by weight of nitrogen (N), phosphorus (P) and potassium (K),
commonly referred to as the N-P-K ratio. For example, if a 100-pound bag of fertilizer
is 20-10-15, it has 20 pounds of nitrogen, 10 pounds of phosphorus and 15
pounds of potassium for a total of 45 pounds of nutrients and 55 pounds of
filler material. Other nutrients are sometimes listed on the label. The law
requires the fertilizer manufacturer to guarantee that the N-P-K ratio of
fertilizer on the label is correct meaning the nutrients listed on the label
are contained in the fertilizer. If you have your soil tested, the report will
recommend the type of fertilizers and amounts that should be applied.
Various
formulations of fertilizers are used. Complete fertilizers contain all three of
the major nutrients. Incomplete fertilizers, such as 0-20-20, do not contain
all three of these nutrients. Slow release fertilizers include a coating of
materials that allow the nutrients to be slowly made available to the plants
over a period. Water, heat, and microbes break the material down. Some
fertilizers are combined with pesticides. However, the timing for a fertilizer
application and treatment for the pest may not coincide. For example, some
fertilizers are formulated with a pre-emergent herbicide. In the spring, the
best time for the use of a pre-emergent is in March. The fertilizer should not
put down on warm-season grasses at that time since it could cause them to come
out of dormancy prematurely and increase the risk of cold damage from a late
season freeze.
Many
gardeners question whether the use of organic fertilizers is advantageous over
synthetic fertilizers. Bone meal, cottonseed meal, blood meal, manure, compost
and other sources are considered organic fertilizers. The advantage to using
them is increasing the organic matter content of the soil and improving its
physical structure. They also are less likely to burn the plant material.
However, the nutrients in organic fertilizer are not in a form where plants can
absorb. They have to be broken down by
soil microbes to be released into the soil. With synthetic fertilizer, the
nutrients are immediately released. Also, the nutrient levels from organic
sources are relatively low. Even if you use synthetic fertilizer, consider
incorporating organic matter into the soil to improve it.
Remember, not all fertilizers are alike. Fertilizer choice is dependent
on the type of plant material that you are growing and the type of soil where
it will be grown. Knowing your soil fertility needs from soil testing and
understanding the different types of fertilizers will help in finding the right
one for your particular situation.
No comments:
Post a Comment