Here the 1858 Wright edition omitted the of in the phrase “the land of Jershon”. As discussed under Alma 27:22–24, either reading is possible. We therefore follow the earliest textual sources in determining whether the of should be here in Alma 43:15.
Summary: Maintain in Alma 43:15 the of in “the land of Jershon” since this is the reading of the earliest textual sources (including 𝓞).