The mention of “lo sossur” that anonymous1000 alluded to is erroneous. There ,we are talking about halachic matters, not “milei d’alma”, matters of general interest. There is no obligation to follow any Rov in matters that are not halachic.
Just for the record, in case anyone is confused by Rabbi of Berlin’s statements, he has previously gone on record that shemita is not considered halacha for this purpose since it is not in the shulchan aruch http://www.theyeshivaworld.com/coffeeroom/topic/about-the-rca-i-do-shudder/page/3