Very interesting.
SACM, Sociedad de Autores y Compositores de Mexico, list the song as follows:

Alla en el Rancho Grande
ISWC: T.035.000.821-7
compositor-autor 00054126011 Uranga Donato Emilio SACM
autor 00054126011 Diaz del Moral Juan SACM
editor original 00160694172 Promontora HispanoAmerica De SACM

The SACM website has a biography of Juan Diaz del Moral, with details of the song and other compositions.
http://www.sacm.org.mx/archivos/biografias.asp?txtSocio=02507

Text is in Spanish, a mostly intelligible English translation is provided.