Use the adjective pastoral to describe the countryside, particularly an idealized view of the country. If you draw cheery pictures with lush fields, calm skies, cheerful bunnies, and colorful wildflowers, you draw pastoral scenes.
Pastoral can also describe something done by, you guessed it, a pastor. If a pastor writes a letter to his congregation, it is a pastoral letter. How are the two meanings of pastoral related? Shepherds, of course. Pastors are often referred to as shepherds of their flock (i.e., the members of their church congregation). Actual shepherds, the kind who tend sheep, work in pastoral settings.