Soil Nutrients and Fertilizers

24.00: Explain the role of nutrients in quality plant growth

Macro vs Micro Nutrients

• Macro nutrients are required by the plant in relatively large amounts

• Micro nutrients are required only in small amounts– minor or trace elements

Macro nutrients

• Non-mineral elements– carbon (C)– hydrogen (H)– oxygen (O)

• Primary Nutrients– Nitrogen (N)– Phosphorus (P)– Potassium (K)

• Secondary Nutrients– calcium (Ca)– magnesium (Mg)– sulfur (S)

Micro nutrients

• Iron (Fe)

• Copper (Cu)

• Zinc (Zn)

• Boron (B)

• Molybdenum (Mo)

• Manganese (Mn)

• Chlorine (Cl)

Functions of Nitrogen

• Promotes growth of leaves and stems

• Gives dark green color and improves quality of foliage

• Necessary to develop cell proteins and chlorophyll

Nitrogen

• Deficiency symptoms– sick, yellow-green color– short stems, small leaves, pale colored

leaves and flowers– slow and dwarfed plant growth

Nitrogen deficiency

Functions of Phosphorus

• Stimulates early formation and growth of roots

• Provides for fast and vigorous growth and speeds maturity

• Stimulates flowering and seed development

• Necessary for the enzyme action of many plant processes

Phosphorus

• Deficiency symptoms– decrease in growth– slow maturity– older leaves are purplish color

Phosphorus Deficiency

Functions of Potassium

• Used to form carbohydrates and proteins

• Formation and transfer of starches, sugars and oils

• Increases disease resistance, vigor and hardiness

Potassium

• Deficiency symptoms– mottled, spotted, streaked or curled leaves– scorched, burned, dead leaf tips and

margins

Potassium Deficiency

Functions of Calcium

• Improves plant vigor

• Influences intake and synthesis of other plant nutrients

• Important part of cell walls

Calcium

• Deficiency symptoms– small developing leaves– wrinkled older leaves– dead stem tips

Calcium Deficiency

Functions of Magnesium

• Influences the intake of other essential nutrients

• Helps make fats

• Assists in translocation of phosphorus and fats

Magnesium

• Deficiency symptoms– Interveinal chlorosis-yellowing of leaves

between green veins– leaf tips curl or cup upward– slender, weak stalks

Magnesium Deficiency

Functions of Sulfur

• Promotes root growth and vigorous vegetative growth

• Essential to protein formation

Sulfur

• Deficiency symptoms– young leaves are light green with lighter

color veins– yellow leaves and stunted growth

Sulfur Deficiency

Iron

• Functions of Iron– Essential for chlorophyll production– Helps carry electrons to mix oxygen with

other elements

• Deficiency symptoms– mottled and interveinal chlorosis in young

leaves– stunted growth and slender, short stems

Iron Deficiency

Copper

• Functions– Helps in the use of Iron– Helps respiration

• Deficiency symptoms– young leaves are small and permanently

wilt– multiple buds at stem tip

Copper Deficiency

Zinc

• Functions– plant metabolism– helps form growth hormones– reproduction

• Deficiency symptoms– retarded growth between nodes (rosetted)– new leaves are thick and small– spotted between veins, discolored veins

Zinc Deficiency

Boron

• Functions– affects water absorption by roots– translocation of sugars

• Deficiency Symptoms– short, thick stem tips– young leaves of terminal buds are light

green at base– leaves become twisted and die

Boron Deficiency

Manganese

• Functions– plant metabolism– nitrogen transformation

• Deficiency symptoms– interveinal chlorosis– young leaves die

Manganese Deficiency

Molybdenum

• Functions– plant development– reproduction

• Deficiency symptoms– stunted growth– yellow leaves, upward curling leaves, leaf

margins burn

Molybdenum Deficiency

Chlorine

• Functions– essential to some plant processes– acts in enzyme systems

• Deficiency symptoms– usually more problems with too much

chlorine or toxicity than with deficiency

Chlorine Deficiency

Fertilizers

Types of Fertilizers

• Complete

• Incomplete

• Organic

• Inorganic

• Soluble

• Insoluble

Complete vs. Incomplete

• Complete has all three primary nutrients-nitrogen phosphorous & potassium– Examples: 10-10-10, 15-30-15, 20-5-20

• Incomplete DOES NOT have all three primary nutrients– Examples: 20-0-0, 0-20-0, 12-0-44

Organic Fertilizers

• Comes from plant or animal matter and contains carbon compounds

• Examples: urea, sludge and animal tankage

Advantages of Organic

• Slow release of nutrients

• Not easily leached from the soil

• Add organic components to growing media

Disadvantages of Organic

• Hard to get

• Not sterile

• Low nutrient content

• Expensive

Inorganic Fertilizers

• Comes from sources other than animals or plants

• Chemical products

Advantages of Inorganic

• Can make the desired ratio of nutrients

• easy to get

• lower cost

Disadvantages of Inorganic

• No organic material

• possible chemical building up in growing media

Soluble Fertilizer

• Dissolve in water and are applied as a liquid solution

• Fertigation– fertilizing through irrigation water– big advantage

Insoluble Fertilizer

• Includes granular and slow release applied to the growing media

Granular vs. Slow Release

• Granular– relatively inexpensive– easy to find

• Slow Release– more expensive because it is coated– more uniform release of nutrients over time

period

Fertilizer Analysis

• Fertilizer analysis expresses weight as a percent of nitrogen, phosphorus and potassium

20-10-20

Fertilizer Analysis

• For Example– A 100 pound bag of fertilizer has an

analysis of 15-5-15. How many pounds of nitrogen, phosphorus and potassium are in the bag?

• Nitrogen: 100lbs X 15%=15lbs• Phosphorus: 100lbs X 5%=5lbs• Potassium: 100lbs X 15%=15lbs

Fertilizer Ratios

• A fertilizer with a 10-10-10 analysis would have a 1:1:1 ratio

• A fertilizer with a 24-8-16 analysis would have a 3:1:2 ratio

• What would be the ratio for a fertilizer with an analysis of 36-18-27?

4:2:3

Application Procedures

• Banding

• Sidedressing

• Topdressing

• Perforating

• Broadcasting

• Foliar spraying

• Fertigation

Banding

• Placing a band of fertilizer about two inches to the sides and about two inches below seed depth.

• DO NOT place below the seeds because fertilizer will burn the roots.

Sidedressing

• Placing a band of fertilizer near the soil surface and to the sides after seedlings emerge from the soil.

Topdressing

• Mixing fertilizer uniformly into the top one to two inches of growing media around the plant.

Perforating

• Placing fertilizer in 12”-18” holes drilled 18” to 24” around the canopy drip line of fruit trees. Cover the holes and fertilizer slowly dissolves.

Broadcasting

• Spreading fertilizer to cover the entire production area

Foliar Spraying

• Spraying micronutrients in a solution directly on plant leaves.

• Quickly corrects nutrient deficiencies

• Fertilizer concentration should not be too high or leaf burning will occur.

Fertigation

• Incorporating water-soluble fertilizer into the irrigation system of greenhouse and nursery crops.

• Concentrated solutions usually pass through proportioners or injectors to dilute to the correct ratio.– Venturi-type– Positive-displacement

Venturi-type

• Simple and inexpensive

• less accurate

• depends on water pressure in the hose and in the smaller tube to proportion

• Example: Hozon

Positive-displacement

• More expensive

• very accurate

• physically inject and mix specific amounts of concentrated solution and water

• Examples: commander proportioners, and Smith injectors

Rules for applying fertilizers

• Method used should be practical, effective and cost efficient

• Method used affects nutrient availability for plant use

• Fertilizer must be dissolved and reach plant roots