Keep in mind that any "prestige" class (the term "advanced" class is not PC) for Disciples of the Land will have very limited combat ability due to the fact that most combat abilities have at minimum a Disciple Of War or Disciple of Magic requirement.

Also keep in mind that Disciples of the Land are gatherer classes. So any prestige class should also "gather something".

All that being said ... Rancher, Shepherd, Breeder, Dowser, Surveyor, Homesteader, Cartographer are all possibilities.