Micronutrients are called micro, because they are

Solution (By Examveda Team)

Micronutrients are called micro because they are needed in small amounts.
Micronutrients are essential dietary elements required by organisms in varying quantities throughout life to orchestrate a range of physiological functions to maintain health.
There are about seven nutrients essential to plant growth and health that are only needed in very small quantities, thus termed Micronutrients.