UNDERSTANDING FERTILIZERS AND THEIR USES
Once the garden soil has been tilled with the organic material and sand
incorporated consider fertilization.
Fertilizer increases plant growth only if it is a limiting factor. Plants
grown in poorly drained soils, in excessive shade or in competition with
tree roots do not respond to fertilizer.
Fertilizer is organic or inorganic. Organic fertilizers are manures, bone
meal, cotton seed or other naturally occurring materials. Inorganic fertilizers
contain manmade products.
The three numbers shown on fertilizer containers are the fertilizer analysis.
They indicate the percent of nitrogen, phosphorus and potassium present
in the fertilizer. These figures are always listed in the same order. So,
a 100-pound sack of 10-20-10 fertilizer contains 10 pounds of nitrogen,
20 pounds of phosphorus and 10 pounds of potassium. That equals 40 pounds
of nutrients. The rest of the fertilizer is simply carrier or filler, such
as sand, perlite or rice hulls. A complete fertilizer is one with all three
elements. A general recommendation for gardens and flower beds is 2-3 pounds
of a slow-release, complete fertilizer such as 19-5-9 per 100 square (10'
X 10') feet of planting area.
Just as people need nourishment, plants must have nutrients to grow and
flourish. Plants need a balanced diet with all of the necessary nutrients
readily available for their use. Plants will grow at optimum rates if nutrition
is furnished on a "as needed" basis. If you incorporate the knowledge
that plants need a continuous source of nutrition with the realization that
the major pollutant of ground water is nitrates which can come from plant
fertilizer applications, then the idea of using slow release fertilizers
to feed plants small portions of the nutrition they need makes sense. Fertilizers
which gradually feed plants rather than deluging them with excessive nitrogen
are not only environmentally-sensible, but they also enable plants to grow
at optimum rates. This is why slow release formulations are recommended
for all plants, whether they are vegetables, flowers, trees, shrubs, groundcovers
When fertilizing gardens, use a product containing slow-release fertilizer
such as sulfur-coated or plastic-covered urea. When choosing a slow release
fertilizer, it is important to note that the higher the percentage content
of sulfur-coated or plastic-covered urea, the better.
The chance of groundwater contamination from excessive nitrates washing
through the soil is lessened when greater amounts of slow release, sulfur-coated
or plastic-coated urea are present. Of course, the more slow-release fertilizer
present, the more expensive the product, but safeguarding the environment
is certainly worth the cost difference!
Some of the better fertilizers will have at least 50 percent of the total
nitrogen content of the bag as sulfur-coated or plastic-coated urea. This
information can be determined by reading the Guaranteed Analysis found on
each bag of fertilizer. Remember, the higher the percentage or units of
sulfur-coated or plastic-coated urea, the more you and the environment benefit.
To insure you have the best product, not only look for the "slow release"
nomenclature on the bag, but you should also examine the Guaranteed Analysis
which indicates what percent of nitrogen (the first number on the bag) is
derived from sulfur-coated or plastic-coated urea.
Slow-release fertilizer in your gardens has the following advantages:
- Makes more nitrogen slowly available as a nutrient to the plant.
- Resists leaching or washing through the soil into the water supply.
- Deceases risk of fertilizer burn associated with heavy applications
of conventional fertilizers.
- Releases independently of microbial and bacterial action.
- Offers controlled-release feeding for 10 weeks.
- Stimulates a more drought-tolerant plant.