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Plant Nutrition

Essential Elements

Macronutrients - needed in large quantities

  • Nitrogen (N)

Involved in all the physiological process taking place in plants

Deficiency:

  • Expressed as a decrease in vigor, chlorotic (yellow) foliage color
  • Older leaves express symptoms first

Excessive Levels:

  • Excessive vegetative growth
  • Decreased flowering and fruiting
  • Predisposition to various pathological and physiological disorders (soft, weak growth and fireblight)

  • Phosphorus (P)

    1. Needed for root development, flowering, and fruit formation.
    2. Essential for cell division.

    Deficiency: 

    • Stunted plant  
    • Development of a bronze or purple coloration of the petioles and leaf undersides 
    • Yellowing of the leaves, particularly at the time of flowering and fruiting  
    • Seldom observed in field grown material                                                                                         

     

  • Potassium (K)

  1. Modifies the absorption of other nutrient elements.  
  2. Influences the carbohydrate-nitrogen relationship.          
  3. Influences the absorption and utilization of water.

Deficiency: 

  • Marginal yellowing of the older leaves followed by scorching and leaf drop
  • Needle evergreens-brown tip, green base, separated by yellow band 
  • Decrease in the number of years that the needles persist  

 

 

  • Calcium (Ca)

  1. Constituent of the cell walls.     
  2. Modifies the permeability of membranes.    
  3. Root development

Deficiency: 

  • Death of terminal portions 
  • Yellowing and necrosis of the adjacent young leaves 
  • Leaf margin distortions (usually on seedlings)   

  • Magnesium (Mg)

  1. Integral part of chlorophyll, the green pigment in plants needed for photosynthesis.  
  2. Certain enzyme systems and respiration do not functions properly at low levels

Deficiency: 

  • Chlorosis on older leaves 
  • Dead areas suddenly developing between leaf veins 

 

  • Sulfur (S)

Constituent of protein

Deficiency: 

  • Plants are stunted 
  • Leaves are light green or yellow, progressing from younger leaves to older 
  • Usually not seen as deficient   
  • Contaminant for other fertilizers and is an air pollutant

Micronutrients - (trace or minor nutrients) needed in very small quantities 

  • Boron (B)

  1. Aids in proper root development, flowering, and fruiting.         
  2. Necessary for nitrogen and carbohydrate metabolism.

Deficiency: 

  • Can be brought on with the application of excess lime (sandy soils) 
  • Death of growing points, brittleness and dieback of stems 
  • Scorched, curled and often rosette leaves   

  • Copper (Cu)

    1. Catalyst in respiration. 
    2. Needed for carbohydrate and protein metabolism and in seed formation

    Deficiency: 

    • Not common is woody perennials 
    • In fruit trees, a withering and death of young shoots in late spring-early summer 
    •  In azaleas, new leaves are smaller than normal and soon become scorched 

  • Iron (Fe)

  1. Catalyst in chlorophyll formation and for oxidation-reduction reactions.
  2. Availability in the soil decreases with high pH or high phosphates 

Deficiency: 

  • Interveinal chlorosis on young leaves with the veins remaining green
  • Dieback of branches on woody perennials 

  • Manganese (Mn)

  1. Needed for assimilation of carbon dioxide in nitrogen metabolism.
  2. Needed for the formation of organic acids and carotene.  
  3. May be deficient in soils of high pH.

Deficiency: 

  • Symptoms similar to those for iron 
  • Reported for red, sugar, and Norway maple 

Toxicity: 

  • Chlorotic leaves, premature defoliation, and suppressed growth raised pimples 
  • Associated with acid soils, anaerobic conditions and steam-pasteurized 

  • Molybdenum Mo)

  1. Needed for protein synthesis     
  2. Seldom limits growth of woody plants 

  • Zinc (Zn)

  1. Functions in cell elongation and in seed development

Deficiency:

  • Uncommon in woody ornamental
  • Produces a yellow to bronze color in older foliage

  • Chlorine    

Soil Reaction (pH)

pH is a measure of the degree of acidity or alkalinity of a soil (H-ion concentration) pH scale of 0 to14. 7 is neutral, below 7 is acidic, above 7 is alkaline each change of 1pH unit is a 10 fold change in hydrogen-ion concentrations soil pH can be determined by using a pH meter or by the use of dyes and test papers primary and secondary nutrients readily available within pH range of 6.0 to 8.0 most woody plants show most favorable soil reaction at a pH of 5.5 to 7.5

Modifying pH

Limestone used to modify a soil that is too acidic. The amount of limestone to be applied varies according to:
  • soil texture, organic matter content, and the form of limestone to be applied
  • Sulfur can be used to acidify a soil
  • pH changes best done in nursery soils when land is not in production
  • When changing soil pH more than one unit, best to make split applications
  • Maximum amount of lime that should be applied in any season in 5 tons/ acre
  • The finer limestone is ground, the more quickly it reacts

Soil Test

  • Necessary for growers to make sound soil management decisions
  • Stay with one testing lab since different extraction methods are used at different labs
  • Soil samples 12-18" deep are needed for trees and shrubs
  • Most soil labs provide soil CEC, pH, and availability of macroelements
  • The microelements, total N, % of organic matter, and soluble salts may be requested
  • Be sure to maintain historical records of results and applications made