Bonds issued under the authority of this chapter shall be full faith and credit obligations of the county or supervisors district for which the same are issued and the board of supervisors shall annually levy upon all taxable property within such county or supervisors district, as the case may be, an ad valorem tax sufficient to pay said bonds at maturity and the interest thereon as it accrues. Said bonds shall bear interest at a rate to maturity not to exceed that allowed in Section 75-17-101, shall be payable semiannually, shall mature within twenty (20) years of the date of issuance in such annual maturities and denominations and shall be in such form as the board of supervisors may direct and such bonds shall not be subject to any limitation relative to amount of bonded debt. Said bonds shall be executed by the signature of the president of the board of supervisors, countersigned by the clerk thereof, under the seal of such board.