Horticulture Principles and Practices

124 Chapter 4 Plant Growth Environment
Liquid Application Liquid fertilizer applications involve applying water-soluble
forms of fertilizer to either the soil or the leaves.
1. Starter fertilizer application. In the vegetable industry, where seedlings are
transplanted, new transplants benefit from a diluted concentration of complete
fertilizer that is applied through the transplant water. Phosphorus is especially
desirable in the starter fertilizer solution, and a general recommendation is about
3 pounds (1.4 kilograms) of 15:30:15 fertilizer in 50 gallons (201.9 liters) of
water, applied at one cup per plant.
2. Foliar application. Soluble fertilizers may be applied in diluted amounts to plants
by spraying directly onto the leaf surface. Since only small amounts of chemicals
are applied, the method is not adequate to meet the nutritional needs of plants.
Supplementary soil application is usually required.
Application of Gas
Application of fertilizer as gas is possible in certain cases, such as the application of
nitrogen in the form of ammonia gas under pressure. This form of nitrogen has a very
high analysis. Application is accomplished by injecting the compound as pressurized gas
into the soil.
4.4.5 METHODS OF APPLICATION
Fertilizers may be applied by using bare hands, machinery, or through irrigation water
when water is administered by sprinklers or tubes. The method chosen depends on
factors such as the size of the area to be fertilized, the form of fertilizer, the placement
method, the crop, and the stage of application.
Dry Application
Manual For a small garden, fertilizers may be manually applied, regardless of the
method of placement chosen. However, the uniformity of application may be questionable
with placement methods such as broadcasting. Manually held or pushed spreaders
are available to facilitate the broadcast operation and for improving uniformity of
application. When applying fertilizer to trees in the landscape or potted plants using dry
formulations, the operation is done by hand.
Mechanized Sometimes fertilizer can be applied at the time of planting seed. This
method of application entails inserting the fertilizer along with the seed using a seed drill
and is called pop-up application. When applied with the seed drill, the fertilizer is placed
in the seed furrow. When applying fertilizer to a large area, it is done more efficiently
and uniformly by using a mechanized system. Mechanized systems enable calibration of
equipment to deliver fertilizer at a uniform rate over an entire area.
Liquid Application
Liquid application of fertilizer to containers on a small scale (e.g., at home) may be
accomplished by dissolving the fertilizer in water and dispensing it with a calibrated
container to the potted plants. A dispenser containing fertilizer may be attached to a
watering hose and used for irrigation (see later section). In greenhouses and fields,
liquid fertilizers are applied through irrigation water.
Foliar Application Most fertilizer applications involve the use of major nutrients,
or macronutrients, applied to the soil. The rates of application are often large and can
injure vegetative tissue on direct contact. Hence, caution should be exercised in
applying dry fertilizer elements by avoiding placing the elements too close to the plant.