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: , , Incomplete DOES NOT have all three primary nutrients –Examples: , ,

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

Fertilizer Analysis For Example –A 100 pound bag of fertilizer has an analysis of 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 analysis would have a 1:1:1 ratio A fertilizer with a analysis would have a 3:1:2 ratio What would be the ratio for a fertilizer with an analysis of ? 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