> the air is notably lacking in both oxygen (for us) and nitrogen (for plants) Minor nitpick: There are only very few plants that are able to extract nitrogen

> the air is notably lacking in both oxygen (for us) and nitrogen (for plants) Minor nitpick: There are only very few plants that are able to extract nitrogen from the air. That's because N2 is a very stable molecule and it takes a lot of energy to use it chemically. Almost all plants are dependent on other nitrogen compounds they extract using their roots. [That's the reason why the invention of the Haber-Bosch process, which fixes the N2 from the air into NH3 (ammonia), was such a big deal. It is estimated that 50% of the nitrogen atoms in your body once passed through the Haber-Bosch process.] There's probably plenty of nitrogen in various minerals on Mars. Just not in the atmosphere.