Aristotle postulated four things viz. air, water, soil and fire are required for the life. He reported that water is essential for plants and plants grow better in dirty water. This idea indicated that dirty water contain nutrient elements which enhance the growth of plants.
In 1972, E. Epstein defined two criteria for an element to be essential for plant growth: (1) in its absence the plant is unable to complete a normal life cycle or (2) that the element is part of some essential plant constituent or metabolite, this is all in accordance with Liebig’s law of the minimum.[1] There are 16 essential plant nutrients.
