Austin Master Gardener(AMG) Learning Resources

Notes, Reading Excerpts, and Research links

nutrient table

N P K, C M S, I M Z, C B M.



Uptake form

Mobility in Plant
Mobility in Soil
Acid Deficiency
Alkaline Deficiency
gas and water C, H, O
Carbon, Hydrogen, Oxygen
Carbon © 50% dry weight  present in all macromolecules CO2, H2CO3
 Carbonic acid
Hydrogen (H) h2o is >80% plant weight part of many organic compounds and also forms water Hydron H+, OHHydroxide , H2O        
Oxygen (O)   necessary for cellular respiration; plants use oxygen to store energy in the form of ATP. O2 oxygen gas        


C M S , (Ca Mg S)

N, P, K    Ca Mg S
Nitrogen, Phosporous, Potassium ;
Calcium, Magnesium, Sulfur
Nitrogen (N) 4.00% A component of chlorophyll, nucleic acids, proteins, and
NO3Nitrate,  NH4+ ammonium ion,
also see Urea CH4N2O , and Ammonium nitrate (NH4NO3)
  Mobile as NO3, immobile as NH4+ y Volatilization Urea
Phosphorus 0.50% Required to store and transport energy HPO42- Hydrogen phosphate,
H2PO4 Dihydrogen phosphate
  Immobile y y
Potassium 4.00% Acts as a osmotic regulator in water absorption and loss
by the plant.
K+     y  
Calcium 1.00% Cell structure, secondary plant hormone Ca2+, see also Lime
calcium carbonate (CaCO3).
Magnesium 0.50% Central ion in the chlorophyll molecule Mg2+   Immobile y  
Sulfur 0.50% A component of nucleic acids and proteins SO4 sulfate ion     y  

I M Z , ( Fe Mn Z)

C B M ,  (Cu B Mo)

Fe, Mn, Zn ; Cu, B, Mo
Iron, Manganese, Zinc, Copper, Boron, Molybdenum
Iron 200 ppm Required for chlorophyll synthesis and
energy transferring pathways
Fe2+, Fe3+ Low Immobile   y
Manganese 200 ppm Required for chlorophyll production
and energy transferring pathways
Mn2+ Low     y
Zinc 30 ppm Activates enzymes Zn2+ Low Immobile   y
Copper 10 ppm Involved in respiration and oxidation/reduction reactions Cu2+ Low Immobile   y
Boron 60 ppm cell division and differentiation of young tissue H3BO3Boric Acid,
Low     y
Molybdenum 1 ppm Involved in nitrogen metabolism MoO4Molybdate Low   y  



Sodium 500 ppm Osmotic regulator Na+     10−3 g mg milligram
Chlorine 0.10% Required for photosynthesis Cl     103 g kg kilogram
Silicon 0.05-0.15% Pathogen defense, drought and heat tolerance H4SiO4     10−6 g µg microgram (mcg)
Cobalt     Co2+ Low   1 ppm =  1/1,000,000 =0.000001 = 0.0001%
= 1 mg/kg
Nickel     Ni2+    

Refrences –

Nutrient Uptake in Plants, Smart Fertilizer

Soil analysis: key to nutrient management planning, PDA

The most commonly found nutrient deficiency and toxicity symptoms are presented in the table below:

NutrientDeficiency SymptomsToxicity Symptoms
Nitrogen (N)Stunted growth and restricted growth of lateral shoots. Plants express general chlorosis of the entire plant to light green and yellowing of older leaves which proceeds to younger leaves. Older leaves become necrotic and defoliate earlyPlants are stunted, deep green in color, and secondary shoot development is poor. High N causes vegetative bud formation instead of reproductive bud formation. Ammonium toxicity can cause roots to turn brown, with necrotic root tips; reduce plant growth; necrotic lesions occur on stem and leaves; vascular browning occurs in stems and roots.
Phosphorus (P)Stunted growth. Purplish coloration of older leaves in some plants. Dark green coloration with tips of leaves dying. Delayed maturity, Poor fruit and seed development.Excess P in the plant can cause iron and zinc deficiencies.     
Potassium (K)Leaf margins turn chlorotic and then necrotic.  Tip and marginal burn starting on mature leaves.  Lower leaves turn yellow.  Weak stalks and plant lodge easily.  Slow growth. High amounts of K can cause calcium (Ca), magnesium (Mg) and N deficiencies.  
Magnesium (Mg)Interveinal chlorosis on older leaves which proceeds to the younger leaves as the deficiency becomes more severe.  The chlorotic interveinal yellow patches usually occur toward the center of the leaf with the margins being the last to turn yellow.   Curling of leaves upward along margins.  High Mg can cause Ca deficiency. 
Calcium (Ca)Light green color on uneven chlorosis of young leaves.  Brown or black scorching of new leaf tips and die-back of growing points.  Growing points of stems and roots cease to develop.  Poor root growth and roots short and thickened. High Ca can cause Mg or Boron (B) deficiencies. 
Sulfur (S)Uniform chlorosis first appearing on new leaves.  
Iron (Fe)Interveinal chlorosis of new leaves followed by complete chlorosis and or bleaching of new leaves.  Stunted growth. 
Zinc (Zn)Interveinal chlorosis of new leaves with some green next to veins.  Short internodes and small leaves.  Rosetting or whirling of leaves.  
Manganese (Mn)Interveinal chlorosis of new leaves with some green next to veins and later with grey or tan necrotic spots in chlorotic areas.  
Copper (Cu)Interveinal chlorosis of new leaves with tips and edges green, followed by veinal chlorosis.  Leaves at the top of the plant wilt easily followed by chlorotic and necrotic areas in the leaves.  Dieback of terminal shoots in trees.  
Boron (B)Death of terminal buds, causing lateral buds to develop and producing a ‘witches broom’ effect. Symptoms develop as a yellow-tinted band around the leaf margins.  The chlorotic zone becomes necrotic and gray, while the major portion of the leaf remains green. 
Molybdenum (Mo) Older leaves show interveinal chlorotic blotches, become cupped and thickened.  Chlorosis continues upward to younger leaves as deficiency progresses.  

Diagnosing Nutrient Deficiencies

EC and pH

pH and ECsymptomscorrections
High salts ECSmall, thick, and dark colored leaves. Lower leaves may turn yellow and brown, especially on the leaf margins. Plants become stunted.   Roots are less vigorous, may have brown leaves, and are likely to become diseased.The solution to high salt levels is usually to “leach out” (apply excess water to wash through the container) the growing medium or potting mix (termed the “root substrate” throughout this book).
Low EC ( see specific nutrient deficiency)“chlorosis” (yellowing, resulting from lack of the green chlorophyll pigment that is essential for photosynthesis). These symptoms can be seen on this geraniu   Nitrogen, phosphorus, and other nutrients are being moved out of its lower leaves to provide N and P to the growing points. The plant is essentially cannibalizing itself, because it cannot get nutrients from the roots.   Growth and flowering can be greatly reduced    The solution to low fertilizer levels is simply to apply more fertilizer. However, it is important to diagnose that nutrient levels are indeed low using an onsite soil test method and checking EC is below the adequate range
Substrate pH is too high (alkaline, pH values above 7 are “basic”)  e.g. Iron Symptoms to look for with iron deficiency at high pH:    Chlorosis either in the entire leaf or between the darker leaf veins (“interveinal chlorosis”)     Symptoms show up first in young leaves, in contrast to an overall low nutrient level, which may be in all or older leaves.   With sensitive plants such as the calibrachoa above, growth is severely stunted and growing points turn white and even necrotic (the tissue dies).Reduce excess limestone, or alkaline water, nitrate fertilizer’s basic effects.   To correct a high pH problem, a combination of acid fertilizer (containing ammonium or urea nitrogen) and adding acid into the irrigation water to remove alkalinity can usually drop substrate-pH.   Drenches (irrigations applied to the root substrate) with additional iron in a highly soluble form are also very effective at corr
Substrate pH is too low (acidity)Mn and Fe toxicity (over availability)   Chlorotic (yellow) or necrotic (brown and dead) spots or leaf margins in older leaves,   In marigold, the symptoms appear as brown sandy-colored spots in older leaves  The most common causes of a drop in substratepH are insufficient limestone, a fertilizer high in ammonium or urea nitrogen, which has an acidic reaction. Some plant species  such as geranium also tend to drop substrate-pH. An application of a liming material such as flowable limestone or potassium bicarbonate, and a change to a basic nitrate fertilizer are needed to raise substrate-pH