For purposes of the several federal crop adjustment programs, the determination of farm program yields is based upon the average program yields of the farm for three of the past five years (the highest and lowest yields of the five years are disregarded) before the effective date of a farm bill (i.e. 1981-1985 for the 1985 farm bill and 1986-1990 for the 1990 farm bill). Thus, if a producer increased production by irrigation after 1985 or after 1990, the farm program yield may not be increased to reflect the irrigated yield