Soil Fertility
Original by Andrew Laca
Modified by Georgia Agricultural
Education Curriculum Office
July, 2002
August 2008
Terms and definitions
• Essential Nutrient- Element necessary for
plant growth and reproduction, for example:
nitrogen, phosphorus, and potassium.
• Deficiency- Plant condition where an
essential nutrient is not sufficiently
available.
• Symptom- A visual sign or condition that
results from a deficiency: symptoms aids in
diagnosing a deficiency.
August 2008
More Terms and Definitions
• Fertilizer- Natural, manufactured, or
processed material or mixture of materials
that contains one or more of the essential
nutrients; available in:
– dry form
– liquid form
– gaseous form
August 2008
Fertilizer Terms
• Analysis- Percentage water soluble
content of nitrogen (N), phosphorus (P)
expressed as P2O5, and potassium (K)
expressed as K2O in the fertilizer.
• Brand- Trademark of the company which
produced the fertilizer.
• Complete Fertilizer- Fertilizer which
supplies all three primary nutrients, (N,P,K)
August 2008
Chemical Elements
Essential To Plant Growth
• Non-mineral- air and • Mineral- from the soil
water
– Primary
–
–
–
–
Carbon (C)
Hydrogen (H)
Oxygen (O)
Nitrogen (N)
• Nitrogen (N)
• Phosphorus (P)
• Potassium (K)
– Secondary
• Calcium (Ca)
• Magnesium (Mg)
• Sulfur (S)
– Micronutrients
• Iron (Fe), Boron (B), Manganese
(Mn), Copper (Cu), Zinc (Zn),
Molybdenum (Mo), Clorine (Cl)
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10 Essential Elements
• Essential Elements
–
–
–
–
–
–
–
–
–
–
Carbon (C)
Hydrogen (H)
Oxygen (O)
Phosphorus (P)
Potash (K)
Nitrogen (N)
Sulfur (S)
Calcium (Ca)
Iron (Fe)
Magnesium (Mg)
C. HOPKINS CAFÉ Mighty Good
August 2008
August 2008
Functions of Nutrients for
plant growth
• Carbon, Hydrogen, and oxygen are
needed in the plant processes of
photosynthesis of photosynthesis and
respiration.
• Approximately 95% of weight of plants
comes from products of photosynthesis
August 2008
Primary Nutrient Functions
• Nitrogen (N)
– Gives green color to plant
– Induces vigorous , rapid growth in plants
– Increases protein and yield
– Aids and promotes seed and fruit development
– Nitrogen constitutes 80% of the atmosphere, yet
it is one of the most critical elements for plant
growth.
– Plants cannot utilize N as a gas, it must be
combined with other elements.
August 2008
More Primary Nutrient Functions
• Phosphorus (P)
– Important to germinating seedlings
– Contributes to early maturing crops
– Necessary for seed and fruit formation
– Stimulates root growth
August 2008
Primary Nutrient Functions
Cont.
• Potassium (K)
– Necessary for production and translocation
of carbohydrates
– Produces plumper seeds
– Controls Water intake and respiration
– Stiffens straw and stalks
August 2008
Secondary Nutrient Functions
• Sulfur (S)
– Necessary for nodule formation on legumes
– Associated with plant enzyme systems
– Stimulates seed production
– Affects protein and crop quality
August 2008
Secondary Nutrient Functions
• Calcium (Ca)
– Speeds decay of organic matter
– Stimulates formation of nitrates
– Promotes root and leaf growth
– Necessary for nodulation of legumes
– Cell Wall formation
August 2008
Secondary Nutrient Functions
• Magnesium (Mg)
– Necessary for chlorophyll or green plant color
– Increases adsorption of phosphorus
– Aids in the formations of fats and oils
– Important in plant enzyme system
August 2008
Symptoms of nutrient
deficiencies
• Review
– Deficiency- Plant condition where an essential
nutrient is not sufficiently available.
– Symptom- A visual sign or condition that
results from a deficiency: symptoms aids in
diagnosing a deficiency.
August 2008
Primary nutrient deficiency
symptoms
• Nitrogen (N)
– Stunted and Spindly
– Yellow, yellowish green or light green in color
in foliage (chlorosis)
– Older leaves affected first, starting at the tip
and moves along the middle of the leaf.
August 2008
August 2008
Primary nutrient deficiency
symptoms
• Phosphorus (P)
– Stunted Growth
– Very dark green color
– Purple leaves or portions of leaves in
advanced stages
– Older leaves affected first
August 2008
Phosphorus Deficiency
August 2008
Primary nutrient deficiency
symptoms
• Potassium (K)
– Shorter plants
– Bronzing or browning of leaf color
– Lodging (bending of the stem) occurs
– Leaves show yellow to brown coloring along
leaf margins followed by complete browning.
August 2008
Potassium Deficiency
August 2008
Secondary nutrient deficiency
symptoms
• Sulfur (S)
– Young plants have stunted appearance
– Leaves have a light-green to yellow coloring
– Stems are thin and spindly
– Sulfur deficiency symptoms are similar in
appearance to nitrogen deficiency symptoms.
August 2008
Secondary nutrient deficiency
symptoms
• Magnesium (Mg)
– Leaf parts between veins show a whitish color
– Leaf tissue becomes yellow, veins remain
green (interveinal chlorosis)
– Leaves curl upward along the margins
August 2008
Secondary Nutrient Deficiency
Symptoms
• Calcium (Ca)
– The symptoms show up first at the growing
tips of both the shoots and the roots.
– New growth at the leaf tips and margins
begins to wither and die back, and the new
leaves are often deformed.
– As cells weaken, the vascular system of the
plant starts to collapse, reducing the uptake of
all of the major elements.
– Plant leaves die.
August 2008
Deficiency Continued
• Other conditions besides deficiencies
may cause abnormal plant growth.
– Cold, wet weather, lack of sunlight,
disease, insect damage, and improperly
applied chemicals are examples.
August 2008
Factors that Influence Fertilizer
Use
• Chemical and physical condition of the soil
• Crop to be grown
• Climatic Conditions
• Time
August 2008