What for of Nitrogen do plants use?

Question

What for of Nitrogen do plants use?

Answer 1

Needs it for nucleic acids, proteins, and hormones, according to a wikipedia article under search "plant physiology" that it will not post here (error 999). It need nitrogen for all proteins, for DNA, growth and reproduction as well. Not enough nitrogen leads to stunting, according to an article "plant nutrition" on wikipedia.

Answer 2

Usually the inorganic forms ammonium and nitrate.  Some plants have been found to take up small, N-containing organic molecules, like amino acids, though.