Question

How do plants take nitrogen?

Answer 1

Plants take nitrogen from the soil by absorption through their roots as amino acids, nitrate ions, nitrite ions, or ammonium ions. Most nitrogen obtained by terrestrial animals can be traced back to the eating ofplants at some stage of the food chain.

Answer 2

generally some bacteria help to fix nitrogen in plants.
now the bacterias can be associated to the plants (symbiosis between rhizobium and root nodules of leguminous plants) or free living in soil.