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.
Irrigation in Peru
Agriculture in Peru dates back more than 5,000 years when the Chavin culture built simple irrigation systems and canal networks north of Lima. By the 15th and 16th centuries, the Inca Empire boasted an advanced irrigation systems, supplying water to 700,000 hectares of diverse crops in the fertile coastal zone. For the next 300 years, Spanish colonialists shifted the country's focus to mining, which caused a reduction in agricultural production to 300,000 hectares in the coast.