Agriculture in the prehistoric Southwest
After the Hohokam disappeared, Spanish explorers of the 16th century noted the use of canal irrigation in only two areas of the Southwest: eastern Sonora, primarily practiced by the Opata and Lower Pima, and among the Pueblos of northern New Mexico. Irrigation by the Opata and Pueblos had different objectives. In Sonora, with a long growing season, two crops of maize a year were grown in river valleys. The spring crop during the dry season was dependent upon irrigation; the summer and fall crop during the rainy season utilized irrigation to supplement rainfall. The necessity of irrigation probably required a high level of social organization. In New Mexico, with only one crop of maize per year possible, irrigation was supplemental and the lesser dependence on irrigation implies less social organization than in Sonora.
Instituto Nacional de Colonización
The Instituto's main goal was to increase agricultural production in Spain by devoting more land surface to agriculture. Priority was given to the development of new irrigated areas in arid and semi-arid zones. This goal was very effective for the propaganda purposes of the new regime and triumphalistic claims were made that the colonization measures would increase self-sufficiency. But often irrigation was opposed to the traditional and sustainable methods of dryland farming that were ecologically more in tune with locally available resources in fragile environments.