Fertilize and aerate now with an Iron Fertilizer. Your grass will turn very green so that you don’t have to water to get it green.
samples and where to send them for analysis.
A soil test report will be accompanied by interpretations and nutrient recommendations
(Figure 1). Nitrogen is the most common nutrient needed. Table 1 summarizes nitrogen
recommendations for a variety of plants. Refer to your soil test report to determine if nitrogen is
needed. Ornamentals such as trees and shrubs, as well as turf, will grow at slower rates if less
nitrogen is used than the recommendations listed in Table 1. Slower growth rates may be desirable
depending on the goal of the landscaper and the intensity of management. Vegetable nitrogen
recommendations are designed to produce optimum yields in a garden setting.
ELECTING A FERTILIZER
formulations are listed in Table 2. Fertilizer labels have been standardized so that the
concentrations of nitrogen, phosphate, and potash always appear in the same order on the front of
the package. Other components such as iron, zinc, or sulfur may be specified elsewhere on the
The variety of fertilizers on the
market means the homeowner can find
a product to meet any need. Minimize
the application of nutrients listed as
adequate, high, or excessive on a soil test
report. Further application of fertilizers
containing these nutrients may create
an imbalance and reduce plant growth.
If a soil test report recommends only
nitrogen, use ammonium nitrate (34-0-
0), ammonium sulfate (21-0-0), or
another fertilizer high in nitrogen
(Table 2). If nitrogen and phosphorus
are recommended, use a fertilizer such
as 30-10-0. Assume for example that a soil test
report recommends 2 pounds (lbs) of nitrogen and 1 pound of phosphate per 1000 square feet.
Using the 20-27-5 formulation (Table 2) would result in the over-application of phosphate, while
the 30-10-0 formulation (Table 2) would slightly under-apply phosphate. The gardener may
decide to apply 20-27-5 for one year and build up soil phosphorus levels, then retest the soil and
switch to a nitrogen-only fertilizer in subsequent years. Alternatively 34-0-0 or 21-0-0 could be
applied to meet the nitrogen requirement and 0-45-0 to meet the phosphorus requirement.
2O5), and potash (or K2O). For2O5), and 5%2O). This means that 4 pounds of 25-3-5 would supply 1 pound of nitrogen (4 x 0.25),
2 to 3 pounds of nitrogen/1000 sq ft
High: onion, sweet corn, potato 4 to 6 pounds of nitrogen/1000 sq ft
Low: peas, beans 1 to 2 pounds of nitrogen/1000 sq ft
Ammonium nitrate 34-0-0
Starter fertilizer 20-27-5
Balanced fertilizer 16-16-16
Ammonium phosphate 11-52-0 or 18-46-0
nutrient concentration in the fertilizer. For example, if a 36 lb bag of 29-3-4 cost $15.88 and a 20
lb bag of 21-0-0 cost $2.99, which is the least expensive source of nitrogen? The cost per pound
of nitrogen is $1.52 for the 29-3-4 and $0.71 for the 21-0-0. More expensive fertilizers often
contain pesticides for weed or insect control, and may have added micronutrients or slow release
characteristics. Compare prices among products and purchase fertilizers with special additives
only if they are needed. Most fertilizers containing herbicides are meant to be used on turf and will
stress ornamental trees and shrubs, and kill most vegetables and flowers. Read and follow label
instructions carefully when using fertilizers containing pesticides.
Vegetable food 12-12-12
length and width. Multiply the length by the width to calculate area. A simple formula used to
calculate the amount of fertilizer required to meet a nutrient recommendation is:
pint volume equals approximately 1 pound of dry fertilizer.
A gardener is using ammonium nitrate (34-0-0) fertilizer to supply 2 pounds of
concentrated sources of nutrients. This means that applicators need to accurately calculate and
apply fertilizers at the appropriate rates to supply the correct amount of plant nutrients without
damaging plants or causing adverse environmental effects.
to 3 feet for low cost units). Rotary spreaders broadcast fertilizer in a 10 to 20 foot wide path
with less uniformity and rate control than drop spreaders. Either spreader type will work well for
homeowners if properly calibrated and operated.
Cooperative Extension Service, Utah State University, Logan, Utah. (EP/DF/02-99)
models. Since manufacturers cannot list
calibration settings for all situations, it is good
practice to calibrate the unit for your use. Set the
spreader to the closest manufacturer’s setting for
the rate and type of fertilizer you will apply. Place
2 pints of kitty litter in the unit and spread in a
continuous straight path. Note the width of the
spread path and the distance traveled to broadcast
the litter. Calculate the rate of application (assuming 1 pint of litter equals 1 pound of fertilizer)
and compare this to the rate needed. For example, if a rotary spreader broadcasts a 10 foot wide
path and you traveled 40 feet to empty 2 pints of litter from the hopper, the rate of application
would be equivalent to 2 pounds per 400 square feet (10 ft x 40 ft), or 5 lbs/1000 square feet. If a
different rate is needed the spreader setting should be changed and the unit calibrated again. Once
a spreader is calibrated for a specific rate keep a record of the setting for future use. .
Avoid streaking caused by fertilizer skips and overlap by applying one-half of the
calculated rate while traveling in one direction and the remaining one-half while traveling in a
perpendicular direction. This method of application is especially useful for turf fertilization where
streaking is common.
Banding (Figure 3) is a convenient way to make in-season fertilizer applications to high
nitrogen requiring vegetables like corn. To band fertilizer first calculate the amount needed for an
area as if you were going to broadcast the material. Divide this amount by the number of plant
rows in the area to determine the amount of fertilizer to apply in each row. Make narrow furrows
8 to 10 inches away from the base of the plants, 2 to 3 inches deep. Distribute the fertilizer evenly
in the furrow and cover with soil.
Foliar applications can be made with any water-soluble product and are commonly used
for applying small amounts of micronutrients such as iron and zinc. There is potential for foliar
burning with sprays so follow product label instructions carefully. A 2% fertilizer solution by
weight is generally safe for use as a foliar spray. Mix a 2% solution by adding 0.15 lb
(approximately 1.25 fluid ounces or 2 ½ tablespoons) fertilizer per gallon of water. Apply foliar
sprays early in the morning or late in the evening to minimize leaf burning. Thoroughly cover
foliage with the spray solution.
specific situation than another, and different fertilizers need to be applied at different rates to
supply the correct amount of plant nutrients.
Improper fertilizer application can contribute to surface and ground water pollution, may
induce a plant nutrient deficiency or toxicity, or cause salt burn. Properly used, inorganic
fertilizers are safe for plants and the environment. The purpose of this guide is to provide general
selection and use information for inorganic fertilizers. See the related guide,