Notwithstanding any other provision of law, whenever a set-aside program is in effect for one or more of the 1982 through 1995 crops of wheat and feed grains, the Secretary of Agriculture may require, as a condition of eligibility for loans, purchases, and payments for such crops under the Agricultural Act of 1949 [7 U.S.C. 1421 et seq.], that producers not exceed the acreage on the farm normally planted to crops designated by the Secretary, adjusted as deemed necessary by the Secretary to be fair and equitable among producers and reduced by any set-aside or diverted acreage. Such normal crop acreage for any crop year shall be determined as provided by the Secretary. The Secretary may require producers participating in the program to keep such records as the Secretary determines necessary to assist in making such determination.