The essential plant nutrients, or essential elements, are listed in the table below.
It enumerates 16 chemical elements of which the essentiality for plant growth and reproduction has been established according to the criteria formulated by D.I. Arnon and P.R. Stout in 1939.
This listing has existed since 1954 with chlorine as the latest addition (cited by Hopkins 1999)
Classification of Plant Nutrients
These plant nutrients are classified into various groups:
1. Major elements and trace elements
Of the 16 listed, 9 are major elements or macronutrients and 7 are trace elements or micronutrients.
Major elements are those which are needed by plants for their growth and reproduction in relatively large amounts while trace elements are needed in smaller amounts compared to the former.
The major elements are further subclassified into structural elements (carbon, oxygen, and hydrogen), primary macronutrients (nitrogen, phosphorus, and potassium), and secondary macronutrients (calcium, sulfur, and magnesium).
2. Mineral and non-mineral nutrients
Mineral nutrients are absorbed by plants primarily in ionic form from the soil while non-mineral nutrients are absorbed either from the soil or from the atmosphere as a component of compounds.
The elements numbered 4 to 16 in the list are considered mineral nutrients.
Carbon, oxygen, and hydrogen are considered non-mineral nutrients.
They are sourced from carbon dioxide (CO2) and water (H2O) which are reactants in the process of photosynthesis.
Table EPN-1. List of essential elements or essential plant nutrients.
| ELEMENT | ATOMIC WEIGHT | FORMS ABSORBED | RANGE OF CONCENTRATION IN DRY TISSUE* |
| Major Elements or Macronutrients | |||
| 1. Carbon (C) | 12.01 | CO2 | 45% (450,000 ppm) |
| 2. Oxygen (O) | 16.00 | CO2, O2 | 45% (450,000 ppm) |
| 3. Hydrogen (H) | 1.01 | H20 | 6% (60,000 ppm) |
| 4. Nitrogen (N) | 14.01 | NO3–, NH4+ | 0.5-6% (5,000-60,000 ppm) |
| 5. Phosphorus (P) | 30.97 | H2PO4–, HPO42- | 0.15-0.5% (1,500-5,000 ppm) |
| 6. Potassium (K) | 39.10 | K+ | 0.8-8% (8,000-80,000 ppm) |
| 7. Calcium (Ca) | 40.08 | Ca2+ | 0.1-6% (1,000-60,000 ppm) |
| 8. Sulfur (S) | 32.06 | SO42- | 0.1-1.5% (1,000-15,000 ppm) |
| 9. Magnesium (Mg) | 24.31 | Mg2+ | 0.05-1% (500-10,000 ppm) |
| Trace Elements or Micronutrients | |||
| 10. Iron (Fe) | 55.85 | Fe2+, Fe3+ | 20-600 ppm |
| 11. Chlorine (Cl) | 35.45 | Cl– | 10-80,000 ppm |
| 12. Manganese (Mn) | 54.94 | Mn2+ | 10-600 ppm |
| 13. Zinc (Zn) | 65.38 | Zn2+ | 10-250 ppm |
| 14. Copper (Cu) | 63.54 | Cu+, Cu2+ | 2-50 ppm |
| 15. Boron (B) | 10.81 | BO33-, H3BO3 | 0.2-800 ppm |
| 16. Molybdenum (Mo) | 95.94 | MoO42- | 0.1-10 ppm |
* Modified from Epstein (1994; ppm equivalent of concentration expressed in percent (%) is supplied).
Note: Emanuel Epstein of the University of California- Davis has added nickel (Ni) to the list of essential plant nutrients (Epstein 1994).
REFERENCES
- EPSTEIN E. 1994. Review: The anomaly of silicon in plant biology. Proc. Natl. Acad. Sci. USA. 91:11-17. Retrieved Nov. 11, 2012, from http://www.pnas.org/content/91/1/11.full.pdf.
- HOPKINS WG. 1999. Introduction to Plant Physiology. 2nd ed. New York, NY: John Wiley & Sons, Inc. p. 61-76.
- MOORE R, CLARK WD, VODOPICH DS. 2003. Botany. 2nd ed. New York, NY: McGraw-Hill. p. 468-495.
