Understanding Plant Nutrition

Nineteen elements are considered essential for plant growth. Carbon, hydrogen, and oxygen are primarily supplied by air and water. Plant roots absorb the remaining 16 elements from the surrounding soil. These elements are divided into three groups based on their relative abundance in plants: Primary Nutrients (or Major Nutrients), Secondary Nutrients (or Minor Nutrients), and Trace Nutrients (or Micronutrients). Although the Major Nutrients are needed in the greatest quantities, a deficiency of any one nutrient can prevent plant growth, or reduce it to unsatisfactory levels. Even though some soils may already contain these nutrients, they may not be in a form available for plant growth. The best way to ensure that all of the nutrients are available in the soil is through regular applications of plant foods.

The table below provides more information on each nutrient, its deficiency symptoms, and possible plant foods to cure the deficiency.

Primary NutrientsFunctionDeficiency Symptoms *Solutions
NitrogenVigorous growth & dark green colorLight green leaves; stunted growth
Dried Blood, Garden Manure, Cottonseed Meal, Urea
Phosphorus Root development & flowering
Smaller yields of seeds & fruit; purplish leaves, stems & branches;Rock Phosphate, Bone Meal, Single Super Phosphate, Triple Super Phosphate
PotassiumOverall hardiness & disease resistance Reduced yields; Spotted or curled leaves; Weak root systemMuriate of Potash, Greensand
Secondary NutrientsFunctionDeficiency Symptoms*Solutions
CalciumPlant vigor; Aids in uptake of nutrientsDeformed terminal leaves; Poor root growthGarden Lime, Garden
Magnesium Essential part of chlorophyll Yellowing of older leavesGarden Lime
Sulfur Dark green color; Seed productionYellow leaves; Stunted,
spindly plants
Soil Acidifier, Gypsum
Trace NutrientsFunctionDeficiency Symptoms *Solutions
BoronIncreases flowering
& fruit development
Terminal buds die; Less
flowers & fruit develop
Garden Manure, Bone Meal
Chlorine Helps control water loss & moisture stress
Plants wilt; yellow leaves Garden Manure, Greensand
CobaltImproves growth &
Reduced growth and
yellowing of foliage
Greensand, Kelp, Cottonseed Meal
CopperHelps produce chlorophyllYellow, wilted leaves;
Lack of flowering
Garden Manure,
IronPromotes dark green
Yellow leavesGreensand, Garden
Manure, Cottonseed Meal
ManganeseHelps produce chlorophyllIntervenous chlorosis in
younger leaves
Garden Manure, Greensand
MolybdenumEssential in some enzyme systemsPale green, rolled or cupped leavesGreensand, Lime (makes it more available)
NickelEnzyme ProductonYellow LeavesGreensand
SodiumAids water regulation & photosynthesisPlants wiltKelp, Garden Manure,
Bone Meal, Greensand
ZincEnzyme & growth
hormone production
Yellow leaves, Rosetted
(clustered) leaves
Garden Manure, Greensand, Cottonseed