What gave you the first clue, Sherlock?
Terraforming is for TERRA - EARTH! Mars is not Earth. Different gravity, amount of sunlight, atmosphere, soil, water supply.
Using astronauts’ poop to fertilize your plants is going to get you killed.
As already stated without a magnetic field, the solar wind will blow the atmosphere away, as it has for millions of years. All this stuff is a liberal pipe dream.