Question

From where does the plants get Nitrogen,Phophorus,Iron and Magnesium to build up their body?

Answer 1

Although nitrogen is present in abundance in atmosphere, yet plants cannot directly absorb the nitrogen. It is because nitrogen is a relatively inert element. Nitrogen is made available to plants through the process of nitrogen fixation which converts the inert nitrogen into utilisable compounds of nitrogen such a nitrate, ammonia, amino acids, etc. These utilisable compounds present in soil are absorbed by roots of plants.
Phosphorus is absorbed as phosphate ions present in soil, iron as ferric ion or ferrous ion, magnesium as Mg²⁺ ions present in soil.