Farm modeling is a thriving community of quality modelers, most of whom are using 1:64 scale products. Since many railroad tracks pass by farm land, it isn't too much of a stretch to consider integrating farming into your model railroad layout, or consider integrating a section of S-scale track with an engine and some cars (or just a siding with a couple of covered hoppers parked on it) into your farming diorama.
We have a listing of current and previously-produced kits and models, which are related to farm modeling, on this web site.