Judging by the example sentences on Naver, this is more "field" as in "open area" (i.e. it there don't necessarily have to be crops planted there), right?
Correct! :D In case you want to know what a Korean word exactly means in the native speaker's head, try image search pls.
The Korean word for "field trip" is 수학여행.
fyi, 수학 is a Sino-Korean word, homonym meaning either mathematics or "to study"