The Hebrew word tsemed indicates a “pair” of oxen. In ISA 5:10 it speaks of the area that two oxen could plow in a day. Some English translations try to employ an equivalent English word, although they cannot agree on just how big the area is. Thus RSV has “ten acres” while GNT has “five acres.” The important point here and in the continuation of the verse is that harvests will be extremely poor. Most translations convey this idea by adding a word like “only,” “barely,” or “merely.”
1SA 14:14: This is a corrupt text. If the word tsemed is correct here, then it indicates the length of a plowed furrow, approximately 20–30 meters (65–100 feet); in other words, Jonathan and his servant killed the Philistine soldiers within about half that distance.