I know this answer comes a little late, but from what I know at least with FS 15 the silos will hold as much as you can put in them.

Seeing as the game has now been out for years and it still hasn't had any updates or dlc to lift it up out of demo playability, it's safe to assume this is it. This is the final cut for the 3DS' version, which could have been so much better with just a few minor adjustments and additives. Some prett...

I think you're referring to one of the other platform versions. There's currently no function to show what state a field is in on the 3DS.