Mars has plenty of Nitrogen, it's in the atmosphere (2% of it). That may be at low pressure, but once you have a few hundred tonnes of industrial equipment on Mars you can start doing things like fractional distillation of the atmosphere, and then you're just pumping Nitrogen out of the atmosphere and using it for whatever you want.
2% of a very low pressure may not seem like much but in total that's about half a trillion tonnes, or half a million cubic kilometers of Nitrogen. It'll be a very long time before that resource is depleted. Additionally, Mars has nitrates, which can be mined and exploited.
2% of a very low pressure may not seem like much but in total that's about half a trillion tonnes, or half a million cubic kilometers of Nitrogen. It'll be a very long time before that resource is depleted. Additionally, Mars has nitrates, which can be mined and exploited.