The definite article the appears to be required here. For all other instances of land Desolation, there is a determiner and it is always the (seven times). Here in 3 Nephi 3:23, Oliver Cowdery seems to have omitted the necessary the in 𝓟, although it is possible that he omitted it originally in 𝓞 and that the 1830 compositor supplied it when he set the type. There are a couple of examples in 𝓞 where Oliver initially omitted the definite article the before the word land:
For further examples of where Oliver omitted the in the manuscripts, if only momentarily, see under 2 Nephi 13:23 and Alma 14:5. The critical text will maintain the necessary the here in “the land Desolation”.
Summary: Maintain the definite article the before land Desolation in 3 Nephi 3:23; Oliver Cowdery accidentally omitted the the here, either in 𝓞 or in P.