The sod would have left an earthy smell, but stiff broom and detergent washing the floor should remove that pretty good.
The fertilizer leaves a heavy, cloying chemical smell that you can feel an oily taste onyour tongue if it is strong. Again, laundry detergent washing of the floor should remove that pretty good - if not, wash again with a degreasing floor cleaner like Castrol Purple Degreaser.
OK - if I get this right, you have bare studs, a brown paper on the outside of the studs, then gypboard or cement board ? If the board is the outside sheathing, presumably Bishopric stucco board - sort of like greenboard today, and the predecessor to Hardie Plank siding, but installed in full sheets with grouted joints, and in your case covered with wire mesh (probably has nail tips from mesh nailing sticking through the inside, so watch out for nail jabs, tetanus risk, etc). Or, since house is stucco, could have been exterior rated plaster board.
The paper is probably builders wrap - a waxy asphaltic-lined brown wrapping paper used untill the 80's much like today's Tyvek housewrap, to cut down on airflow in buildings without insulation or a vapor barrier in warm climates, and stop minor water infiltration from stucco cracks. It smells very musty, though not real bad, when old - sort of like an old cardboard box smell with a bit of asphalt smell in the background. Pretty much disintegrates after about 25 years. I would take a utility knife and score it all around the stud edges, then peel it off the cement board - some will stick where the asphalt adhered but should come off pretty fair. Be prepared to kill silverfish - they like the stuff, and commonly you will hit pockets of them removing the paper - they nest in damp spots between the paper and the sheathing or siding.
After all that cleaning, on a dry preferably breezy morning spray the inside face of the siding and the studs with a 50% solution of chlorine bleach like clorox and water, enough to make it turn color darker but not soaked. Use excellent ventilation while doing this - house door closed, garage windows open, fan if no back window to cause a car door to back window draft. Let dry with doors open (at least leave rollup door open 6 inches or so, at a minimum) so maybe a weekend when you are home for at least a day, then don't plan on doing anything more in there for a couple days more with wondows open still, but garage door can be closed for security if needed.
That should take care of the problem - if a musty smell continues, start looking for leaking pipes or garage roof leaks.