Lighter, the Lomaxes attribute the song to Sylvano R. Ramos, copyright 1927, Edward B. Marks Music Corp. This is more likely than attribution to Uranga, who seems to have been active about a decade later, but I think the song is even older.

In ABFS, the version is credited by the Lomaxes to a publication of the Texas Folk-Lore Society. The full reference should be:

Joaquin Moro, 1931, "Songs the Vaqueros Sing," p. 119, in "Southwestern Lore," ed. J. Frank Dobie, Publ. Texas Folk-Lore Society, no. 9, 1931.
Moro makes no mention of author, and provides music, coro and first verse only. If the song was composed only four years earlier, it is surprising that Moro and the Texas Folk-Lore Society did not credit the author.
Moro is cited as an architect, living in Austin, TX, reared in the Rio Grande Valley and a former resident of northern Mexico.