Appointments to fill expired terms in the office of drainage commissioners shall be made by the presiding judge of the district court of the county having jurisdiction of the drainage district at the courthouse therein, during the first ten days of September, or as soon thereafter as possible, on a day fixed by the court at least thirty days before such appointment is to be made and a written notice of the time fixed, mailed under direction of the court to each landowner of the district in each district in which such terms expire.