Horticulture Principles and Practices

TABLE 4–9
Common Inorganic Fertilizers That Supply Essential Nutrients for
Plant Growth and Development
Fertilizer Element Fertilizer Analysis
Nitrogen (N) Ammonium sulfate 20-0-0
Ammonium nitrate 33-0-0
Diammonium phosphate 18-46-0
Sodium nitrate 15-0-0
Potassium nitrate 13-0-44
(Ammonia gas) (82-0-0)
Phosphorus (P) Superphosphate 0-20-0
Triple (treble) superphosphate 0-40-0
Dicalcium phosphate 0-52-0
Diammonium phosphate 18-46-0
Monoammonium phosphate 11-48-0
Potassium (K) Potassium chloride 0-0-60
Potassium nitrate 13-0-44
Chemicals that provide micronutrients include magnesium sulfate (Mg), iron sulfate (Fe), borax (Bo), copper sulfate (Cu),
epsom salt (Mg), sulfur (S), manganese sulfate (Mn), and calcium nitrate (Ca).
Iron
For foliar application, iron chelates or ferrous sulfate may be used.
120 Chapter 4 Plant Growth Environment
Molybdenum Foliar spraying of sodium molybdate or application to seed or soil is
effective in correcting the deficiency problem.
Manganese Like other trace elements, foliar application of manganese sulfate is
commonly used to remedy any deficiency.
Zinc Foliar application of a zinc sulfate solution or a chelate may be used to correct
deficiency problems.
4.4.3 SOIL NUTRITIONAL MONITORING
The grower must regularly monitor plants in production to ensure that the best nutrition
required for optimum productivity is being provided. A timely intervention can usually
save the season’s production from being mediocre in terms of quality and quantity. Three
systems are used to monitor the nutrient status of a soil or growing medium—
visual diagnosis, soil testing, and foliar analysis. These systems differ in scope, accuracy,
cost, and ease of implementation. It is best to use a combination of systems in making a
diagnosis.
Visual Diagnosis
As its name implies, visual diagnosis is based strictly on observation. Since it is an after
the-fact test, significant damage may already have been inflicted. The seriousness of the
damage depends on the nature of the operation and the stage at which the deficiency is
observed. Some symptoms are observed early in the development of the plant, whereas
others manifest themselves when the plant is mature. For problems with early signals,
the damage may be completely reversible; however, usually the damage is only partially
reversible.
The deficiency symptoms associated with the various essential nutrients have been
discussed previously in the section on nutrient elements. These symptoms range from
color changes to physical deformities and death of tissue (necrosis). One weakness of
visual diagnosis is the lack of specificity. Often, one symptom may be unique and typical
of specific nutrient deficiencies. For example, witches’-broom is typical of boron deficiency.