may not carry out the feedstock flexibility program described in subsection (b) for the 2020 or subsequent crops. . 4. Two-year extension of marketing allotments for sugar and subsequent administration of tariff-rate quotas (a) Flexible marketing allotments for sugar (1) Sugar estimates Section 359b(a)(1) of the Agricultural Adjustment Act of 1938 ( 7 U.S.C. 1359bb(a)(1) ) is amended in the matter preceding subparagraph (A) by striking 2018 and inserting 2020 . (2) Stocks-to-use ratio Section 359k(b) of the Agricultural Adjustment Act of 1938 ( 7 U.S.C. 1359kk(b) ) is amended by adding at the end the following: (3) Stocks-to-use ratio Notwithstanding paragraphs (1) and (2), the Secretary shall adjust tariff-rate quotas established under subsection (a) in such a manner as to ensure, to the maximum extent practicable, that— (A) the final ratio of sugar stocks to total sugar use at the end of a fiscal year is— (i) 14.5 percent for fiscal year 2019