if you think about it, it makes some sense because arts students are believe not to know anything about agriculture thats why. You can look at the agric colleges requirement and see
Qualification for agricultural colleges.
Three (3 ) years for SSSCE/ WASSCE students. Applicants must have aggregate 24 or better in the core subjects (English,Mathematics,Integrated Science) and any other three(3) Elective (Physics,Chemistry,Biology,General Agriculture,Fisheries,Animal Husbandry,Horticulture, etc) subjects.WAASSCE applicants must have credit in the Core subjects and at least C6 in any three (3) of the a fore-named Elective subjects.
As you can see, no arts students qualify for any of the electives at all.