Estimates of Prehistoric Irrigated Field Crop Productivity: Sonoran Desert

​By Robert C. Hunt

Robert Hunt is a social and economic anthropologist with a long-term interest in irrigation and agriculture. A key element in the study of prehistoric southwestern environments is the relationship of variation in moisture supply to variation in human behavior. Moisture variation is widely assumed to be correlated with variation in plant productivity; thus, moisture variation has a direct effect on food supply and in turn on human behavior. However, we know little to nothing about particular plant productivity responses to variation in water supply. The question Hunt addresses in Chapter 5 is, How did the Mesoamerican field crops (maize, beans, squashes, cotton) respond to variation in water supply? Hunt’s chapter summarizes what we know about the yields of irrigated field crops in the Sonoran Desert part of the Southwest. It was possible to extract considerable information about maize but not about the other crops. Plausible approximations of maize’s response to that variability are presented. Reviews of the situation for the other field crops reveal how little we know. The evidence supports Karen Adams’s hypothesis in Chapter 1 that traditional southwestern maizes are adapted to different altitudes. The best solution for acquiring more knowledge of plant yields is to conduct systematic agronomy experiments.