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.
Matengo people
The traditional farming methods of the Matengo are known as "Ingolo" or "Ngolo". Over the last 100 years, the Matengo have developed an innovative method of farming on the steep hills, digging pits on ridges on steep slopes to prevent soil erosion and to promote sustainable fertile soils. The function of the pits is to prevent heavy rain washing away the soils on the steep slopes, acting as sedimentation tanks to trap green grasses, thus providing a source of nutrients for the following season. The main crops they grow are staple food crops and coffee under this unique system of cultivation known as "Matengo Pit Cultivation". This cultivation practice usually starts in March following the rainy season.