Ross Geddes (personal communication, 12 July 2004) suggests that the noun call may be a mistake here. He points out that this use of call is the only example of the word call being used as a noun in the entire Book of Mormon text. Consequently, he considers a number of possible emendations, including call as a mishearing for all, but ultimately he rejects this possibility and others. Nothing seems to work. He recognizes that the intended meaning here seems to be ‘need’ (as if the text read “and thus we see the great need of the diligence of men to labor in the vineyards of the Lord”). The word call is extant in the original manuscript.
It turns out that the Oxford English Dictionary lists under definition 8a for the noun call the meaning ‘need’ (as in “there was no call for that behavior” or “he had no call to do that”, more or less idiomatic uses of call that prevail in modern English). The OED gives the following citations (accidentals unchanged) from Early Modern English where call is used much like it is in Alma 28:14:
So the meaning for call as ‘need’ will definitely work in Alma 28:14.
Summary: Maintain the noun call in Alma 28:14 (“and thus we see the great call of the diligence of men”); although its use in this passage seems strange to English speakers today, it has the meaning ‘need’ (a general meaning that dates back to Early Modern English).