The question may be submitted at a special bond election called for that purpose or at a general district election. If called upon petition of the electors of the district, the question shall be submitted not later than the ninetieth day after the filing of the petition therefor with the secretary of the board. The notice calling the election shall be entered in the minutes of the board and in addition to other requirements of this chapter governing the general district election shall contain a statement of the purpose of the proposed bond issue, the amount of bonds proposed to be issued, and the rate of interest, not exceeding six per cent, to be paid thereon.