[hn_throwaway_99]

Nitrogen is often the limiting factor for ALL plant growth, which is why it's the primary component of fertilizer.

Nitrogen in air is not normally available to organisms. The triple bond between the 2 nitrogen atoms is very strong and takes a good deal of energy to break. Some bacteria can do this, and legumes famously have evolved to house bacteria capable of fixing nitrogen in their roots.

The main way we get nitrogen to agricultural plants today is by the industrial production of ammonia, which takes enormous amounts of energy and lots of fossil fuels as presently implemented.