I can't say about your tractor for sure, but I posted this a little while ago about a typical starter.
The big wire from the battery to the starter usually doesn't have a fuse. Likewise the big ground (normally negative (-)) wire from the battery to the chassis won't have a fuse.
I like to take a screwdriver and short across the solenoid from the battery wire to the ignition wire. If the starter turns, then your battery and starter is OK, and start looking at either the ignition circuit or the safety switches.