Chapter 12 - Plant Nutrition

Essential Plant Elements

• Primary Macronutrients

- Nitrogen (N)

- Phosphorus (P)

- Potassium (K)

• Secondary Macronutrients

- Calcium (Ca)

- Magnesium (Mg)

- Sulfur (S)

• Micronutrients

- Iron (Fe)

- Copper (Cu)

- Zinc (Zn)

- Boron (B)

- Molybdenum (Mo)

- Manganese (Mn)

- Nickel (Ni)

- Chlorine (Cl)

Nitrogen

Functions:

- component of chlorophyll, proteins and nucleic acids

- responsible for vegetative growth

deficiency symptoms (stunting, chlorosis)

General Information:

- mobile within plant

- ionic forms: NH4+, NO3

-

Nitrogen Cycle

Nitrogen in the Soil

• very mobile and active

• form is highly dependent upon microbes

Organic N Inorganic N NH4

+

Inorganic N NO3

-

nitrification

(warm, MWD, neutral pH soils)immobilization

mineralization

(wet soils)

den

itri

fica

tio

nle

ach

ing

atmosphere

Phosphorus

Functions:

- the “energy” element

- needed for good root development, flowering and fruiting

- component of cell membranes

deficiency symptom (purplish coloration)

General Information:

- mobile within plant

- ionic forms: HPO4-2, H2PO4

-

Potassium

Functions:

- helps regulate stomatal opening/closing

- needed to prevent lodging (stem toppling)

- improves disease resistance

deficiency symptom (marginal scorching)

General Information:

- mobile within plant

- ionic form: K+

Calcium

Functions:

- component of cell walls and membranes

- needed for apical (tip) growth of roots and shoots

deficiency symptom (blossom end rot)

General Information:

- immobile within plant

- ionic form: Ca+2

Magnesium

Functions:

- component of chlorophyll

- assists in activating various enzyme systems

deficiency symptom (interveinal chlorosis)

General Information:

- mobile within plant

- ionic form: Mg+2

Sulfur

Functions:

- component of several amino acids

- responsible for the pungent flavors of many crops

deficiency symptoms (stunting, chlorosis)

General Information:

- variable mobility within plant

- ionic form: SO4-2

Iron

Functions:

- needed for chlorophyll production

- involved in various reactions in photosynthesis

deficiency symptom (interveinal chlorosis)

General Information:

- immobile within plant

- ionic forms: Fe+2, Fe+3

Nickel

Functions:

- needed for urea metabolism (form of N)

- especially important for legume crops

deficiency symptoms (leaf tip necrosis, deformed leaves - “mouse-ear”)

General Information:

- mobile within plant

- ionic form: Ni+2

Zinc

Functions:

- assists in activating various enzyme systems

deficiency symptoms (interveinal chlorosis, shortened internodes)

General Information:

- immobile within plant

- ionic forms: Zn+2

Manganese

Functions:

- needed for chlorophyll production

- needed for nitrogen metabolism

deficiency symptoms (interveinal chlorosis, brownish-black speckling)

General Information:

- immobile within plant

- ionic forms: Mn+2

Copper

Functions:

- needed for chlorophyll production

- assists in activating various enzyme systems

deficiency symptom (leaf tip die back)

General Information:

- immobile within plant

- ionic forms: Cu+2

Molybdenum

Functions:

- needed for nitrogen metabolism

- needed by legume crops for N fixation

deficiency symptoms (chlorosis with marginal necrosis)

General Information:

- mobile within plant

- ionic forms: MoO4-2

Boron

Functions:

- needed for integrity of cell walls and membranes

- needed to insure good pollination

deficiency symptom (abnormal apical development)

General Information:

- immobile within plant

- ionic form: H3BO3

Chlorine

Functions:

- involved in photosynthesis

- helps regulate stomatal opening/closing

toxicity symptoms (chlorosis with tip and marginal burn)

General Information:

- mobile within plant

- ionic forms: Cl-