The president and treasurer of the university, residing at Columbia, and treasurer of the University of Missouri-Rolla, residing at Rolla, shall, at each annual meeting of the board, prepare and submit to the board a carefully prepared statement of the probable amount of income, as near as may be, of the university and all its departments for the year following, and the curators shall thereupon make an estimate of the probable expenses of the institution and each of its departments for the ensuing year, based upon the statements above mentioned, and make the necessary appropriations to meet said expenses for the current year; and in no instance shall the board of curators create any indebtedness in any one year above what they can pay out of the annual income of said year.