Nitrogen absorbed by plants is

Nitrogen absorbed by plants is reduced to ammonia.
Nitrogen assimilation is the formation of organic nitrogen compounds like amino acids from inorganic nitrogen compounds present in the environment.
Organisms like plants, fungi, and certain bacteria that can fix nitrogen gas (N₂) depend on the ability to assimilate nitrate or ammonia for their needs.
Plants absorb nitrogen from the soil in the form of nitrate (NO₃^-) and ammonium (NH₄⁺). In aerobic soils where nitrification can occur, nitrate is usually the predominant form of available nitrogen that is absorbed.