Here the 1874 RLDS edition omitted the definite article the before the word parts; the 1908 RLDS edition restored the original the (which is extant in 𝓞). Either reading is acceptable, so we follow the earliest textual sources. Elsewhere in the text, wherever there is a choice, we get examples of only “all parts”, never “all the parts”:
In any event, the critical text will maintain here in Alma 46:28 the definite article the in the phrase “in all the parts of the land”.
Summary: Maintain in Alma 46:28 the definite article the before parts (“in all the parts of the land”), the reading in both manuscripts and all the early editions.