Why is nitrogen fixation necessary in nature? 10 points to the first person to answer!?
Basic reason is that life on Earth needs nitrogen (you need it to make amino acids!), and it’s really, really unreactive as N2. When it’s fixed by bacteria into other molecules, it allows plants to absorb and use it, and indirectly allows higher organisms on the food chain to use it, too, by eating the plants, eating the herbivores, etc.
