Which one among the following is not a micronutrient for plants?

Essential plant nutrients are classified into macronutrients and micronutrients based on the quantity required for growth. Macronutrients are needed in larger amounts and include nitrogen, phosphorus, potassium, calcium, magnesium, and sulphur [2]. Specifically, magnesium (Mg) is categorized as a secondary macronutrient. In contrast, micronutrients are required in very small or trace amounts. The primary micronutrients include iron (Fe), manganese (Mn), boron (B), copper (Cu), molybdenum (Mo), zinc (Zn), nickel (Ni), and chlorine (Cl) [2]. While iron, manganese, and chlorine are explicitly listed as micronutrients across multiple sources [2], magnesium is consistently grouped with the macronutrients because it is a central component of the chlorophyll molecule and is required in higher concentrations for plant structural and metabolic functions. Therefore, magnesium is not a micronutrient.

Sources

1. [2] Indian Economy, Nitin Singhania .(ed 2nd 2021-22) > Chapter 9: Agriculture > FERTILISERS > p. 302
2. [1] Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 25: Agriculture > z. Micronutrientsl > p. 363