Soil FertilityAgriculture Science

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.

More Terms and Definitions

• Fertilizer- Natural, manufactured, or processed material or mixture of materials that contains one or more of the essential nutrients; availible in:– dry form– liquid form– gaseous form

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)

Chemical Elements Essential To Plant Growth

• Non-mineral- air and water– Carbon (C)– Hydrogen (H)– Oxygen (O)– Nitrogen (N)

• Mineral- from the soil– Primary

• 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)

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

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

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.

More Primary Nutrient Functions

• Phosphorus (P)– Important to germinating seedlings

– Contributes to early maturing crops

– Necessary for seed and fruit formation

– Stimulates root growth

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

Secondary Nutrient Functions

• Sulfur (S)– Necessary for nodule formation on legumes

– Associated with plant enzyme systems

– Stimulates seed production

– Affects protein and crop quality

Secondary Nutrient Functions

• Calcium (Ca)– Speeds decay of organic matter

– Stimulates formation of nitrates

– Promotes root and leaf growth

– Necessary for nodulation of legumes

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

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.

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.

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

Phosphorus Deficiency

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.

Potassium Deficiency

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.

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

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.

Factors that Influence Fertilizer Use

• Chemical and physical condition of the soil

• Crop to be grown

• Climatic Conditions

• Time