There are 20 mineral elements essential for plant growth.
Carbon (C), hydrogen (H), and oxygen (O) are supplied by air and water.
The six macronutrients are required by plants in large amounts and include
- nitrogen (N)
- phosphorus (P)
- potassium (K)
- calcium (Ca)
- magnesium (Mg)
- and sulfur (S),
The rest of the elements are required in trace amounts (micronutrients). Essential trace elements include
- boron (B)
- chlorine (Cl)
- copper (Cu)
- iron (Fe)
- manganese (Mn)
- sodium (Na)
- zinc (Zn)
- molybdenum (Mo)
- and nickel (Ni).
Studies have also shown that a number of other mineral elements are beneficial to the growth of plants and are required for some plants. Beneficial mineral elements include silicon (Si) and cobalt (Co).
While the beneficial elements are known to be essential to some plants, they are not deemed to be essential for all plants. The distinction between beneficial and essential is often difficult in the case of some trace elements. Cobalt for instance is essential for nitrogen fixation in legumes. It may also inhibit ethylene formation and extend the life of cut roses.
Silicon, deposited in cell walls, has been found to improve heat and drought tolerance and increase resistance to insects and fungal infections. Silicon, acting as a beneficial element, can help compensate for toxic levels of manganese, iron, phosphorus and aluminum as well as zinc deficiency.
A more holistic approach to plant nutrition would not be limited to nutrients essential to survival but would include mineral elements at levels beneficial for optimum growth. With developments in analytical chemistry and the ability to eliminate contaminants in nutrient cultures, the list of essential elements will most likely increase in the future.