29 CFR 780.607: “Primarily employed” in agriculture.

Not only must the employee be employed in agriculture, but he must be “primarily” so employed during the particular workweek or weeks in which the 13(b)(13) exemption is to be applied. The word “primarily” may be considered to mean chiefly or principally (Agnew v. Board of Governors, 153 F. 2d 785). This interpretation is consistent with the view, expressed by the sponsor of the exemption at the time of its adoption on the floor of the Senate (107 Cong. Rec. (daily ed., April 19, 1961), p. 5879), that the word means “most of his time.” The Department of Labor will consider that an employee who spends more than one-half of his hours worked in the particular workweek in agriculture, as defined in the Act, is “primarily” employed in agriculture during that week.