Nutrient
| Action Mode
| Deficiency
| Excess
| Comments
|
Nitrogen (N)
| Absorbed as NO3-, NH4+; responsible for rapid foliage growth and green color; easily leaches from soil, especially NO3-; mobile in plant, moving to new growth
| Reduced growth, light green to yellow foliage (chlorosis); reds and purples may intensify with some plants; reduced lateral breaks; symptoms appear first on older growth
| Succulent growth, leaves are dark green, thick and brittle; poor fruit set; excess ammonia can induce calcium deficiency
| The best NH4+/NO3- ratio is 1/1; high NH4+ under low light can cause leaf curl; uptake inhibited by high P levels; indoors, best N/K ratio is 1/1 unless light is extremely high; in soils with high C/N ratio more N should be supplied.
|
Phosphorus (P)
| Promotes root formation and growth; affects quality of seed, fruit and flower production; increased disease resistance; does not leach from soil readily; mobile in plant, moving to new growth
| Reduced growth; leaves dark green; purple or red color in older leaves, especially on the underside of the leaf along the veins; leaf shape may be distorted; thin stems; limited root growth
| Shows up as micronutrient deficiency of Zn, Fe, or Co
| Rapidly "fixed" on soil particles; when applied under acid conditions, fixed with Fe, Mn and Al; under alkaline conditions fixed with Ca; high P interferes with micronutrient and N absorption; used in relatively small amounts when compared to N and K; availability is lowest in cold soils.
|
Potassium (K)
| Helps plants overcome drought stress; improves winter hardiness; increased disease resistance; improves the rigidity of stalks; leaches from soil; mobile in plant
| Reduced growth; shortened internodes; margins of older leaves become chlorotic and burn; necrotic (dead) spots on older leaves; reduction of lateral breaks and tendency to wilt readily; poorly developed root systems; weak stalks
| Causes N deficiency in plant and may affect the uptake of other positive ions such as Mg and Ca
| High N/low K favors vegetative growth; low N/high K promotes reproductive growth (flower, fruit); calcium excess impedes uptake of potassium
|
Magnesium (Mg)
| Absorbed as Mg++; leaches from sandy soil; mobile in plant
| Reduction in growth; yellowish, bronze, or reddish color of older leaves, while veins remains green; leaf margins may curl downward or upward with a puckering effect
| Interferes with Ca uptake; small necrotic spots in older leaves; smaller veins in older leaves may turn brown; in advanced stage, young leaves may be spotted
| Mg is commonly deficient in foliage plants because it is leached and not replaced; epsom salts at a rate of 1 teaspoon per gallon may be used two times a year; Mg can be absorbed by leaves if sprayed in a weak solution; dolomitic limestone can be applied in outdoor situations to rectify a deficiency
|
Calcium (Ca)
| Absorbed as Ca++; moderately leachable; limited mobility in plant; essential for growth of shoot and root tips; reduces the toxicity of aluminum and manganese
| Inhibition of bud growth; roots can turn black and rot; young leaves are scalloped and abnormally green; leaf tips may stick together; cupping of maturing leaves; blossom end rot of many fruits, pits on root vegetables; stem structure is weak; premature shedding of fruit and buds
| Interferes with Mg absorption; high Ca usually causes high pH which then precipitates many of the micronutrient so they become unavailable to the plant
| Ca is rarely deficient if the correct pH is maintained; too much or too little water, can affect Ca relationships within the plant causing deficiency in the location where Ca was needed at the time of stress
|
Sulfur (S)
| Absorbed as SO4-; leachable; not mobile; contributes to odor and taste of some vegetables
| Rarely deficient; general yellowing of the young leaves then the entire plant; veins lighter in color than adjoining interveinal area; roots and stems are small, hard and woody
| Sulfur excess is usually in the form of air pollution
| Sulfur excess is difficult to control but rarely a problem.
|
