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COURSE:
6841 Horticulture I
Unit C
Soil, Nutrients, and Fertilizers
ESSENTIAL STANDARD:
6.00
10%
C2
Explain the role of nutrients and
fertilizers.
Objective:
6.01
5%
C2
Discuss macro and micro nutrients
and the role they play in plant
deficiencies.
A. Nutrients are elements needed by a plant to promote healthy tissue, processes, and growth.
When plants are lacking in nutrients have a deficiency and may have a number of symptoms:
I.
They will have a stunted appearance,
II.
Pale green or yellow color (chlorosis) may develop initially, but coloring can be related
to the nutrient that is lacking
III.
A general appearance of being unhealthy.
B. Macronutrients - nutrients that plants need in large amounts
I.
II.
III.
IV.
Macronutrients include three primary elements and three secondary elements.
Three primary nutrients are Nitrogen (N), Phosphorus (P) and Potassium (K).
Three secondary nutrients are Calcium (Ca), Magnesium (Mg) and Sulfur (S).
Three primary nutrients needed in the LARGEST amounts
1. Nitrogen (N)
a. Functions
1) Promotes growth for leaves and stems.
2) Gives dark green color and improves quality of the foliage.
3) Is necessary to develop cell proteins and chlorophyll.
b. Deficiency symptoms
1) Sick yellow-green leaves.
2) Short stems, small leaves, pale colored leaves and flowers.
3) Slow and dwarfed plant growth.
2. Phosphorus (P)
a. Functions
1) Stimulates early formation and growth of roots.
2) Provides for fast, vigorous growth and speeds maturity.
3) Stimulates flower and seed development.
b. Deficiency symptoms
1) Decrease in growth.
2) Slow to maturity.
3) Older leaves are purplish color.
3. Potassium (K)
a. Functions
1) Used to form carbohydrates and proteins.
2) Used in the formation and transfer of starches, sugars and oils.
3) Increases disease resistance, vigor and hardiness.
b. Deficiency symptoms
1) Mottled, spotted streaked or curled leaves.
2) Scorched, burned dead leaf tips or margins.
V.
Secondary nutrients are still needed in large amounts
1. Calcium (C)
a. Functions
1) Improves plant vigor.
2) Influences intake and synthesis of other plant nutrients or elements.
3) Improve part of the cell walls.
b. Deficiency symptoms
1) Small developing leaves and wrinkled older leaves are evident.
2) Dead stem tips are evident.
2. Magnesium (Mg)
a. Functions
1) Influences the intake of other essential nutrients.
2) Helps make fats.
3) Assists in translocation of phosphorus and fats.
b. Deficiency symptoms
1) Interveinal chlorosis is the yellowing of leaves between green veins.
2) Leaf tips are curled and cupped upward.
3) Causes slender, weak stems.
3. Sulfur (S)
a. Functions
1) Promotes root growth and vigorous vegetative growth.
2) Essential to protein formulation.
b. Deficiency symptoms
1) Young leaves are light green with lighter color veins
2) Leaves are yellow and stunted.
C. Micronutrients or trace elements are nutrients that plants need in very small amounts.
1. Iron (Fe)
a. Functions
1) Is essential for chlorophyll production.
2) Helps to carry electrons to mix oxygen with other elements.
b. Deficiency symptoms
1) Mottled and interveinal chlorsis are found in young leaves.
2) Causes stunted growth and slender, short stems.
2. Copper (Cu)
a. Functions
1) Helps with the use of iron.
2) Helps with respiration.
b. Deficiency symptoms
1) Young leaves are small and permanently wilted.
2) Multiple buds at stem tips.
3. Zinc (Z)
a. Functions
1) Helps with the plant’s metabolism.
2) Helps form growth hormones.
3) Helps with plant reproduction.
b. Deficiency symptoms
1) Slows growth between nodes.
2) New leaves are thick and small.
3) Spots between the veins and discolored veins.
4. Boron (B)
a. Functions
1) It affects water absorption by the roots.
2) It translocates or moves sugars throughout the plant.
b. Deficiencies symptoms
1) It causes short, thick stem tips.
2) The young leaves of terminal buds are light green at the base.
3) The leaves become twisted and die.
5. Molybdenum (Mo)
a. Functions
1) Is used for plant development.
2) Is used for reproduction.
b. Deficiency symptoms
1) Stunted plant growth is evident.
2) It causes yellow leaves, upward curling leaves and leaf margin burn.
6. Manganese (Mn)
a. Functions
1) It helps the plants metabolism.
2) It helps with nitrogen transformation.
b. Deficiency symptoms
1) Interveinal chlorosis is evident.
2) The young leaves die.
7. Chlorine (C)
a. Functions
1) Essential to some plant processes.
2) Acts in the enzyme system.
b. Deficiency symptoms
1) Usually there are more problems with too much chlorine or toxicity than
with a deficiency.
2) Chlorine is found in the soil.
COURSE:
6841 Horticulture I
Unit C
Soil, Nutrients, and Fertilizers
ESSENTIAL STANDARD:
6.00
10%
C2
Explain the role of nutrients and
fertilizers.
Objective:
6.02
5%
C2
Discuss the advantages and
disadvantages of various fertilizers.
A. Complete and Incomplete fertilizers
1. A fertilizer analysis label will indicate the amount of nitrogen (N), phosphorus (P) and
potassium (K) contained in a fertilizer as a percentage by weight for each element. For
example, 10-20-10 will have 10% Nitrogen, 20% phosphorus, and 10% potassium.
2. Complete fertilizers have all three primary elements. N, P, K (10-10-10, 20-5-20).
a. An advantage is the plants receive all essential elements.
b. A disadvantage is some plants may not need all essential elements.
3. Incomplete fertilizers do not have all three primary elements. (20-0-0, 0-20-0).
a. An advantage is plants need a selective element.
b. A disadvantage is plants may need more elements.
B. Organic or inorganic fertilizers
1. Organic fertilizers are by products of plant or animal matter and contain carbon
compounds such as urea, sludge and animal tankage.
a. Advantages
1) The fertilizer is released slowly reducing the risk of over fertilizing.
2) It is not easily leached from the soil.
3) It improves the water holding capacity of the soil.
4) Improves the physical condition of the soil.
5) Adds organic components to the growing media.
b. Disadvantages
1) It has a smell and is heavy.
2) It is expensive.
3) Some are not sterile.
4) It has low nutrient content.
2. Inorganic fertilizers come from sources other than animals or plants.
a. Advantages
1) It contains the three essential nutrients (N, P, and K) in desired amounts.
2) The fast release capability makes it readily available for plants.
3) It is easy to get as most commercial fertilizers are in an inorganic form.
b. Disadvantages
1) It contains no organic matter.
2) It can cause a chemical build up in soil.
3) It leaches out in heavy rain or through irrigation.
4) It has a high acid concentration which leads to high soil acidity.
C. Soluble and insoluble fertilizers
1. Soluble fertilizers
a. Soluble fertilizers dissolve in water and are applied as a liquid solution.
b. Water soluble fertilizer applied through irrigation systems.
2. Insoluble fertilizers
a. Insoluble fertilizers include granular and slow release fertilizers.
b. Granular fertilizers are relatively inexpensive and easy to find.
c. Slow release fertilizers are more expensive than granular because they are
coated.
d. Slow release fertilizers give a more uniform release of nutrients over a period of
time.
D. Methods of applying fertilizers
1. Banding or starter application is placing a band of fertilizer about two inches to the sides
and about two inches below the seed depth. The band method is close enough to
efficiently supply the young plants with nutrients, but not too close to damage developing
roots.
2. Side-dressing refers to the spreading of fertilizer in between the rows and around the
plants after seedling emerge from the soil.
3. Topdressing is mixing the fertilizer uniformly into the top one to two inches of growing
media around the plant.
4. Perforating is placing the fertilizer in twelve- eighteen inch holes drilled eighteen to
twenty four inches around the drip line of trees. Be sure to cover the holes after fertilizer
is applied.
5. Broadcasting is spreading fertilizer to cover the entire production area.
6. Fertigation is incorporating water soluble fertilizer into the irrigation system of a
greenhouse or on nursery crops. Concentrated solutions usually pass through an
inexpensive proportioner (Hozon) or a more accurate injector (Smith injector) to dilute
the correct ratio.
7. Foliar spray is spraying nutrients in a solution directly on plant leaves. It is used to
correct nutrient deficiencies, but the fertilizer concentration should not be too high or leaf
burn will occur.