| Element (abbreviation; absorbed form) | Typical amount in plant (g/kg dry wt) | Major functions | Deficiency symptoms |
|---|---|---|---|
| Macronutrients | |||
| Nitrogen (N; NO3– and NH4+) | 15 | In proteins, nucleic acids | Oldest leaves turn yellow and die prematurely; plant is stunted |
| Phosphorus (P; H2PO4– and HPO4 | 2 | In nucleic acids, ATP, phospholipids, and phosphoproteins | Plant is dark green with purple veins and is stunted |
| Potassium (K; K+) | 10 | Enzyme activation; water balance; ion balance; stomatal opening | Older leaves have dead edges |
| Sulfur (S; SO2 | 1 | In proteins and coenzymes | Young leaves are yellow to white with yellow veins |
| Calcium (Ca; Ca2+) | 5 | Affects the cytoskeleton, membranes, and many enzymes; second messenger | Growing points die back; young leaves are yellow and crinkly |
| Magnesium (Mg; Mg2+) | 2 | In chlorophyll; required by many enzymes; stabilizes ribosomes | Older leaves have yellow stripes between veins |
| Micronutrients | |||
| Iron (Fe; Fe2+ and Fe3+) | 0.1 | In active site of many redox enzymes and electron carriers; chlorophyll synthesis | Young leaves are white or yellow |
| Chlorine (Cl; Cl–) | 0.1 | Photosynthesis; ion balance | Leaf tips wilt; leaves turn yellow and die |
| Manganese (Mn; Mn2+) | 0.05 | Cofactor for many enzymes | Younger leaves are pale with green veins |
| Boron [B; B(OH)3] | 0.02 | Required for proper cell wall formation and expansion | Poor growth of leaves and roots |
| Zinc (Zn; Zn2+) | 0.02 | Enzyme activation; auxin synthesis | Young leaves are abnormally small; older leaves have many dead spots |
| Copper (Cu; Cu2+) | 0.006 | Cofactor for some redox enzymes and electron carriers | New leaves are dark green, may have dead spots |
| Nickel (Ni; Ni2+) | 0.001 | Activation of the enzyme urease | Leaf tips die; deficiency is rare |
| Molybdenum (Mo; MoO4 | 0.0001 | Cofactor of enzymes involved in nitrogen reduction | Leaves turn yellow between veins; older leaves die |