Some plants slurp nitrogen out of the air. This is inefficient since atmospheric nitrogen is M2, which is quite stable and happy to stay that way. Takes a lot of energy to break that bond.
Other plants create microbial biomes in their root systems that fix nitrogen for them in forms that are easier to absorb, like ammonium and nitrate, which are much cheaper to use. The plant gets bioavailable nitrogen for cheap, the soil gets leftover fixed nitrogen, and the bacteria get a home. In a healthy ecosystem other plants can crib off the leftover nitrogen and provide benefits of their own, like fixing topsoil or creating biomes for fungi to recycle dead matter back into useful nutrients.
Some plants slurp nitrogen out of the air. This is inefficient since atmospheric nitrogen is M2, which is quite stable and happy to stay that way. Takes a lot of energy to break that bond.
Other plants create microbial biomes in their root systems that fix nitrogen for them in forms that are easier to absorb, like ammonium and nitrate, which are much cheaper to use. The plant gets bioavailable nitrogen for cheap, the soil gets leftover fixed nitrogen, and the bacteria get a home. In a healthy ecosystem other plants can crib off the leftover nitrogen and provide benefits of their own, like fixing topsoil or creating biomes for fungi to recycle dead matter back into useful nutrients.