> There are plenty of plants that fix nitrogen already, and nitrogen fixing plants would dominate an ecosystem if Nitrogen were a primary constraint on growth.
You said this with such confidence I had to look this up, because I am quite familiar with the types of plants referred to as “nitrogen fixing plants” such as legumes. But here’s the answer for anyone else curious:
“Nitrogen fixing plants don't pull nitrogen from the air on their own. They actually need help from a common bacteria called Rhizobium. The bacteria infects legume plants such as peas and beans and uses the plant to help it draw nitrogen from the air. The bacteria converts this nitrogen gas and stores it in the roots of the plant.”
Plants fix nitrogen in common parlance but you are technically correct: I sincerely hope that your scientific pedantry works out better for you than it has for me (I won't delve into that topic further).
"Please respond to the strongest plausible interpretation of what someone says".
The research was specifically about introducing nitrogen-fixing organelles into plants because they have none. Precision is valuable since this was in direct contradiction to the original topic. Maybe common parlance is better-suited to a thread on vegetable gardening than microbiology.
“Nitrogen fixing plants don't pull nitrogen from the air on their own. They actually need help from a common bacteria called Rhizobium. The bacteria infects legume plants such as peas and beans and uses the plant to help it draw nitrogen from the air. The bacteria converts this nitrogen gas and stores it in the roots of the plant.”
https://www.gardeningknowhow.com/garden-how-to/soil-fertiliz...