Anyone can verify if a field needs tending. "The crops grow steadily" means the field is in order, while "It could use a touch from the rake or some other farming tool" means it must be tidied with a [[rake]]. If the description mentions "rotting old weeds", the field is overgrown and can no longer be harvested.
Level 10 5 farmers can determine which type of crop is growing in a field, except at the lowest growth level ("freshly sown").
Level 15 farmers can mouse over a field and determine crop type, and whether or not the field is tended or untended (ie needs farming)