The document discusses plant nutrients and their functions. It identifies three categories of nutrients - macronutrients which are needed in large quantities, secondary nutrients which are needed in moderate quantities, and micronutrients which are needed in small quantities. It then provides details on the specific functions and deficiency symptoms of various individual nutrients including nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, iron, manganese, molybdenum, and zinc. It also outlines conditions that can reduce the availability of nutrients to plants.

1. THE PLANT NUTRIENTS
Macro Nutrients
Carbon (C)
Used in exceptionally large quantities
Hydrogen (H)
Oxygen (O)
Nitrogen (N)
Used in large quantities
Phosphorus (P)
Potassium (K)
Secondary Nutrients
Calcium (Ca)
Magnesium (Mg) Used in moderate quantities
Sulfur (S)
Micronutrients
Boron (B)
Chlorine (Cl)
Cobalt (Co)
Copper (Cu)
Iron (Fe)
Manganese (Mn)
Used in small quantities
Molybdenum (Mo)
Nickel (Ni)
Silicon (Si)
Sodium (Na)
Zinc (Zn)
Vanadium (Va)
Carbon, Hydrogen and Oxygen represent 90-96% of the dry matter of all plants. These
elements are supplied by atmospheric carbon dioxide and water. The plant obtains the
remaining 4-10% from the soil and/or fertiliser inputs.

2. A more detailed table listing approximate concentrations of nutrient elements required for
healthy plant growth is as follows.
Concentration in dry matter
Element ppm %
Hydrogen 60 000 6.0
Carbon 420 000 42.0
Oxygen 480 000 48.0
Nitrogen 14 000 1.4
Potassium 10 000 1.0
Calcium 5 000 0.5
Magnesium 2 000 0.2
Phosphorus 2 000 0.2
Sulfur 1 000 0.1
Chlorine 100
Iron 100
Boron 20
Manganese 50
Zinc 20
Copper 6
Molybdenum 0.1
Sodium trace
Cobalt trace
Silicon trace
*Edwards D.G. (1971) Concepts of essentiality and function of nutrients
In commercial agriculture the following elements are applied, when necessary, to improve
crops.
Macronutrients Secondary Nutrients Micronutrients
Nitrogen (N) Calcium (Ca) Zinc (Zn)
Iron (Fe)
Phosphorus (P) Magnesium (Mg) Manganese (Mn)
Copper (Cu)
Potassium (K) Sulfur (S) Boron (B)
Molybdenum (Mo)

3. NUTRIENT FUNCTIONS IN THE DEFICIENCY SYMPTOMS CONDITIONS THAT SENSITIVE
PLANT REDUCE AVAILABILTY CROPS
• an essential element in all • lighter green or yellow coloured light or sandy soils where All crops are sensitive to
living systems leaves (first evident in older leaves) nitrate nitrogen is leached nitrogen deficiency
• needed by all cells – some plants eg. berries can water logged soils
Nitrogen • occurs in the living develop red or orange colours soils with structural problems
(N) substance (protoplasm) of • stunted growth
lower protein levels in pasture and
as a result of poor aeration
mineral soils low in organic
cells •
• a major component of grain matter
protein • delayed maturity soils where nitrogen has been
• a major component of • decreased resistance to disease depleted by previous crops
chlorophyll which converts and/or insect attack soils where the ammonium
sunlight into plant energy • smaller fruit form has been applied to high
• affects both yields and • lower yields pH soils (free ammonia)
quality. • shorter storage life
• necessary for proper cell • reduced growth – sometimes soil with a pH less than 5.5 or Cereals, maize, broccoli,
division and the formation of stunted and other times only more than 7.0 cabbage, cucumber,
new cells evident from shortened internodes, soil with a high clay content lettuce, potatoes, soft
Phosphorus • photosynthesis smaller leaves and reduced shoot mineral soils low in organic fruits, tree fruits
(P) • sugar and starch formation
•
growth.
dark green colour in some crops
matter
soil with high levels of hydrous
(particularly citrus) and
tomatoes.
• energy transfer
• carbohydrate transport. • purple leaves in others eg. oxides of aluminum or iron
brassicas soils where phosphorus has
• reduced tillering in cereals been depleted by previous
• small misshapen fruit – can be crops
pulpy with poor storage life
• poor seed development

4. NUTRIENT FUNCTIONS IN THE DEFICIENCY SYMPTOMS CONDITIONS THAT SENSITIVE
PLANT REDUCE AVAILABILTY CROPS
• aids photosynthesis and the • light green to yellow older leaves continuously cropped soils with Apples, beans, berries,
functioning of chlorophyll which later develop marginal leaf low levels of organic matter broccoli, citrus, cucurbits,
• important for the formation scorch- different plants have their soils without balanced fertiliser grapes, legumes, lettuce,
and translocation of own visual deficiency symptoms programs maize, nuts, passionfruit,
starches, sugars and fats • plant growth is retarded light sandy soils where peas, potatoes, rhubarb,
Potassium potassium has been leached stone fruit, sunflowers,
• involved in protein formation • lodging
(K) • aids many enzyme actions • disease resistance is reduced periods of drought
prolonged periods of heavy rain
tomatoes.
• helps cells maintain their • stalks are weakened
internal pressure • seed and fruit is misshapen some clay soils (eg.
• reduces wilting and Krasnozems)
respiration by maintaining soils in which deficiencies of
the balance of salts and phosphorus and molybdenum
water in cells have been corrected
• improves crop quality heavily limed soil
soils formed from parent
• increases root growth and
material low in potassium
resistance to disease and
drought
• decreases lodging.
necessary for the proper terminal buds and root tips fail to • low pH soils. Tree crops, fruit and
functioning of growing develop normally. • where there is an unfavourable vegetables.
points particularly root tips • lodging balance of calcium, magnesium
forms compounds which • stunted root systems and potassium in the soil Calcium is not easily
strenghten cell walls • leaves of grasses do not open (particularly heavy potassium translocated in plants, so
Calcium aids in cell division and properly the tips of which stick to inputs in sandy soils) a constant supply is
elongation the next lowest leaf where high rates of nitrogen required. This should be
(Ca) neutralises organic acids • soft fruit
•
have been used foliar applied and in
aids in the proper working • senescent breakdown and poor fruiting crops be available
and permeability of cell storage life of fruit from after flowering
membranes • internal and external disorders of onwards.
regulates protein synthesis many fruit and vegetables
and slows the aging
process.

5. NUTRIENT FUNCTIONS IN THE DEFICIENCY SYMPTOMS CONDITIONS THAT SENSITIVE
PLANT REDUCE AVAILABILTY CROPS
the only mineral constituent • interveinal chlorosis beginning in • sandy acid soils – particularly in Vines, pome fruit, stone
of the chlorophyll molecule the tips of older leaves. Veins high rainfall areas fruit, citrus, maize,
aids plants to form sugars remain green, the chlorotic areas • course textured soils in humid tomatoes, capsicums,
Magnesium and starches change from yellow to brown (other regions broccoli, cauliflower,
plays an important part in colours in some plants). • cold wet conditions lettuce, potatoes, parsley,
(M) the translocation of • leaves become brittle and necrotic • soils where there have been pumpkin and many
phosphorus and may drop prematurely heavy inputs of potassium others.
aids several plant enzymes • yield can be seriously reduced • soils which have received
to function. • cotton leaves develop a purplish – repeated green manuring
red colour between green veins
• some varieties of black grapes and
stone and pit fruit can develop
interveinal red chlorotic areas
• grass tetany in sheep and cattle
• excessive premature fruit drop
similar requirements to • generally very similar to nitrogen soils low in organic matter that Cotton, clovers, phalaris,
phosphorus in plants deficiency - a uniform pale green to have been cropped for many barrel medic, lucerne,
a constituant of several yellow leaf but the difference is years. canola, wheat, barley,
Sulfur amino acids which are sulfur deficiency starts in the new maize, sunflowers,
essential for protein leaves whereas nitrogen deficiency acid sandy soils where sulphate soybean, navy beans,
(S) production starts in the old leaves. has been leached - especially sorghum, oats and
aids the activities of some • In legumes the nodules produced such areas with high winter triticale.
are smaller, pale rather than pink rainfall.
enzymes and vitamins
needed for chlorophyll and reduced in number
formation • deficiencies in field crops include
deficiency adversely affects poor low yielding plants, low
the oil content in some oil protein and pale green and yellow
crops and the baking quality leaves in wheat.
in wheat crops
aids efficient nitrogen
stabilisation
needed for nodule formation
in legumes

6. NUTRIENT FUNCTIONS IN THE DEFICIENCY SYMPTOMS CONDITIONS THAT SENSITIVE
PLANT REDUCE AVAILABILTY CROPS
plays a role in cell division, • thick, curled and brittle tissues – high pH soils Cotton, barley, maize,
aids efficient translocation cracking and splitting, sometimes overlimed soils oats, sorghum,
Boron of calcium, with gumosis soils with high levels of nitrogen sunflower, clover,
(B) protein synthesis,
carbohydrate metabolism,
• surfaces of leaf, petioles, stems
and midribs develop cracks or a
and/or calcium
sandy soils that are easily
lucerne, navy beans, soy
beans, citrus, nuts, pome
pollen viability corky appearance leached fruit, stone fruit, root
flower and fruit set and • reduced flowering, seed set and soils with low organic content crops and vegetables.
formation. fruit set. cold wet weather (especially
Hormone formation • Growth points can die forming following a long dry spell)
multiple side shoots
• Small misshapen fruit
• Internal flesh disorders and
cracking in fruit and vegetables
required for chlorophyll • marginal chlorosis of young leaves soils with excess nitrogen Cereals, maize, lucerne,
production sometimes necrotic tips (if severe) and/or phosphorus citrus trees, carrots,
helps with photosynthesis • twig dieback high pH soils lettuce and onions
aids in the production of • sometimes necrotic and brown heavily limed soils
enzyme protein spots over leaf surface soils that have had
Copper involved in several enzyme molybdenum applied
• reduced growth and yields
(Cu) systems
involved in several oxidation
peat and muck soils – high in
organic matter
reduction reactions and the leached acid soils
formation of lignins alkaline and calcarious soils
helps regulate water cold wet conditions (availability
movement in plants. can often be delayed at spring
Required for seed time)
production soils with high concentrations of
iron and manganese
soils formed from parent
materials low in copper

7. NUTRIENT FUNCTIONS IN THE DEFICIENCY SYMPTOMS CONDITIONS THAT SENSITIVE
PLANT REDUCE AVAILABILTY CROPS
necessary for the formation • young leaves – interveinal high pH soils Vines, fruit crops, stone
of chlorophyll chlorosis with green veins after heavy liming fruits, citrus, vegetables,
aids in photosynthesis • later in season – yellowing of soils with high levels of metallic field peas, beans and
Iron involved in the oxidation leaves (margins and tips can ions cereals
process that releases scorch) poorly drained and/or aerated
(Fe) energy from starches and • stunted growth soils
enzymes • reduced yield and quality soils with high levels of copper
aids in the formation of soils with low potassium levels
proteins especially when associated
involved in the conversion with high potassium levels
of nitrate to ammonia in the
plant.
aids respiration.
essential for chlorophyll • chlorosis of recently matured high pH soils Citrus, pome fruit, stone
production and leaves with no reduction in leaf limed soils fruit, vines, strawberries,
photosynthesis. size light sandy soils tomatoes, potatoes,
Manganese aids nitrogen and • less pronounced mottling in some soils low in potassium legumes, vegetables,
carbohydrate metabolism broad leaf plants soils low in organic matter cereals (especially oats),
(Mn) oxidation reduction • small grains can show a soil high in copper, iron and sorgham
involved in the activity of longitudinal striping zinc
several enzymes • “grey fleck” in oats cold wet periods
combines with copper, iron • chlorosis in citrus (more evident on soils that have evolved from
and zinc to aid plant growth the shady side of the tree parent materials low in
processes. manganese

8. NUTRIENT FUNCTIONS IN THE DEFICIENCY SYMPTOMS CONDITIONS THAT SENSITIVE
PLANT REDUCE AVAILABILTY CROPS
is a co-factor in the enzyme • in general similar to nitrogen low pH soils – particularly if Cucurbits (cucumbers,
nitrate-reductose deficiency - yellowing or pale they contain aluminium and/or melons etc.)
aids in the conversion of leaves, stunting, necrotic leaf iron oxides Crucifers (cabbage,
Molybdenum nitrates of ammonium (the margins and tips (this is because soils with high copper levels canola, cauliflower etc.)
initial stage of synthesis of without molybdenum plants cannot soils with low phosphate levels Legumes (beans,
(Mo) proteins) metabolise nitrogen) – symptoms soils derived from parent lucerne, peas, soya
essential for Rhyzobia to start in older leaves first materials low in molybdenum beans etc.)
enable legume crops to fix • flowers can wither or be
aerobic (atmospheric) suppressed
nitrogen
helps plants to utilise nitrate
nitrogen
involved in phosphate and
iron metabolism
necessary for the formation • stunted growth soils evolved from parent Cereals, cotton, fruit, pip
of chlorophyll • leaves reduced in size and material low in zinc and citrus trees, nuts,
Zinc involved in several enzyme misshapen high pH soils and soils heavily oilseed crops, pome fruit,
systems, the growth limed rice, stone fruit,
(Zn) hormone auxins and the
• chlorosis (leaf mottling) leading to
necrosis and premature leaf fall clay soils with high magnesium vegetables.
synthesis of nucleic acids • chlorotic leaves and dieback in levels
plays a part in the intake citrus soils high in organic matter
and use of water in by • rosetting and/or “little leaf” in fruit soils high in potassium
plants. trees soils that have been leveled,
• “tram lining” – light striping both exposing the sub-soils
sides of the midrib- in maize soils that have had high
• bronze spotting on older leaves nitrogen inputs
later giving a mottled appearance cold wet conditions (availability
in legumes can often be delayed at spring
time)
• reduced development and size of
fruit

9. POSSIBLE EFFECTS OF pH AND SOIL TYPE ON NUTRIENT AVAILABILITY
Low pH <6.0 Normal pH 6.0 – 7.0 High pH >7.0
Nitrogen Nitrogen Nitrogen
Phosphorus Potassium Phosphorus
Sandy soils Potassium Magnesium Potassium
Magnesium Sulfur Magnesium
Sulfur Boron Sulfur
Boron Copper Boron
Copper Manganese Copper
Molybdenum Zinc Iron
Zinc Manganese
Zinc
Nitrogen Nitrogen Nitrogen
Phosphorus Magnesium Phosphorus
Potassium Sulfur Magnesium
Sandy Loam Magnesium Boron Sulfur
Copper Copper Boron
Molybdenum Manganese Copper
Zinc Iron
Manganese
Zinc
Phosphorus Boron Boron
Potassium Manganese Copper
Molybdenum Iron
Loam Manganese
Zinc
Phosphorus Manganese Boron
Clay Loam Potassium Manganese
Molybdenum Zinc
Phosphorus Boron
Clay Molybdenum Manganese
Zinc
Phosphorus Copper Boron
Copper Manganese Copper
Organic soils – Peat Zinc Zinc Manganese
Zinc
Magnesium Magnesium Magnesium
Thin soil over Copper Copper
Limestone Manganese Manganese
Zinc Zinc

10. NUTRIENT MOBILITY
Nutrient mobility in soil
Very Mobile – (prone to leaching)
nitrate Nitrogen, sulfate Sulfur, Boron
Moderately Mobile –
ammonium Nitrogen ( ammonium Nitrogen is temporarily immobile),
Potassium, Calcium, Magnesium, Molybdenum
Immobile –
organic Nitrogen, Phosphorus, Copper, Iron, Manganese, Zinc
(Chelated forms of Copper, Iron, Manganese and Zinc are mobile and
resistant to leaching)
Nutrient mobility in plants
Very mobile –
Nitrogen, Phosphorus, Potassium, Magnesium
(Deficiency symptoms appear first in older leaves and quickly spread
throughout the plant)
Moderately mobile –
Sulfur, Copper, Iron, Manganese, Molybdenum, Zinc
(Deficiency symptoms first appear in new growth but do not readily
translocate to old growth)
Immobile –
Boron, Calcium
(Calcium is very immobile)

11. SOIL ANTAGONISM AND INTERACTION CHART
Manganese
(Mn)
Calcium
Potassium (Ca)
(K)
Copper
(Cu)
Iron
(Fe)
Phosphorus
(P)
Magnesium
(Mg)
Molybdenum
(Mo)
Boron
(B)
Zinc
Nitrogen (Zn)
(N)
Interaction
Antagonism

12. NUTRIENT ANTAGONISM AND INTERACTION
NITROGEN
When high levels of Nitrogen induce accelerated growth rates, levels of micronutrients that
would normally be marginal can become deficient.
High soil levels of Nitrogen can assist Phosphorus, Calcium, Boron, Iron and Zinc but an
excess can dilute these elements.
Low soil levels can reduce Phosphorus, Calcium, Boron, Iron and Zinc uptake.
Ammonium Nitrogen can make Molybdenum deficiency appear less obvious.
PHOSPHORUS
High levels of Phosphorus reduce Zinc and, to a lesser degree, Calcium uptake. It is
antagonistic to Boron in low pH soils.
POTASSIUM
High levels of Potassium reduce Magnesium and to lesser extent Calcium, Iron, Copper,
Manganese and Zinc uptake. Boron levels can either be low or toxic.
Low levels can accentuate Iron deficiency.
CALCIUM
High levels of Calcium can accentuate Boron deficiency. Liming can decrease the uptake of
Boron, Copper, Iron, Manganese and Zinc by raising soil pH.
COPPER
High levels of Copper can accentuate Molybdenum and to a lesser degree Iron, Manganese
and Zinc deficiency.
IRON
Iron deficiency can be accentuated by limimg, low Potassium levels or high levels of Copper,
Manganese or Zinc.
MANGANESE
High levels of Copper, Iron or Zinc can accentuate Manganese deficiency – especially
repeated soil applications of Iron. Uptake can be decreased by liming or increased by Sulfur
applications (because of the affects on pH)

13. MOLYBDENUM
Deficiencies can be accentuated by high levels of Copper and to a lesser degree
Mnaganese. Uptake can be adversely affected by sulfates. Uptake can be increased by
phosphates and liming.
Molybdenum can increase Copper deficiencies in animals.
ZINC
Uptake can be decreased by high Phosphorus levels, liming or high levels of Copper, Iron or
Manganese. Zinc deficiencies are often associated with Manganese deficiencies, especially
in citrus.

14. EFFECT OF SOIL REACTION ON AVAILABILITY OF NUTRIENTS
The availability of nutrients at specific pH ranges differs between mineral and organic soils.
The following charts demonstrate these differences.
Influence of pH on the availability of plant nutrients in mineral soils; wildest parts of the shaded areas indicate maximum availability of each
element
Adapted from L.B.Nelson (Ed.) Changing Patterns in Fertiliser Use, Soil Science Society America, Madison,WI (1968).
Influence of pH on the availability of plant nutrients in organic soils; widest parts of the shaded areas indicate maximum availability of each
element.
Adapted from E.E. Lucas and J.F. Davis. Relationships between pH values of organic soils and availability of 12 plant nutrients, Soil
Science 92:177-182 (1961)