If said assessments should for any reason be insufficient to meet the interest and principal of said drainage refunding bonds additional assessments shall be made to provide for such deficiency. [C27, 31, 35, §7714-b18; C39, § 7714.19; C46, 50, 54, 58, 62, 66, 71, 73, 75, 77, 79, 81, §463.19 ] 89 Acts, ch 126, §2 CS89, §468.558