Encyclopedia of the Incas

altitude crops of the quechua zone included maize, quinoa, squashes of many
varieties, beans of even more varieties, chili peppers, and other crops. The puna
zone saw the cultivation of hardy plants such as potatoes, of several hundred
varieties; oca and ullucu, two other native tubers; and other types of plants. The
puna also provided pasture par excellence for llamas and alpacas. Some farmers
grew crops at altitudes that exceeded 4,000 meters (13,000 feet), higher than in
other regions of the world (see Andes, Central; Foodstuffs, Domesticated).
In the highlands, farming systems adapted to the local geography. In valleys
where the three zones were located relatively close to each other, farmers placed
fields in the different zones to grow a variety of plants. In addition, they spaced
their fields to avoid losing their entire crop to a hailstorm, pest infestation, or
early frost. Where flat land was at a premium, terracing was developed to
increase farming outputs. Rainfall dictated whether irrigation systems were
needed.
In regions where the three ecozones were spaced far apart, such as the
altiplano of southern Peru and Bolivia, other means existed for procuring the
resources of distant zones. Using llama caravans, people exchanged produce
between villages located in the different zones. This system is still in use today
in southern Peru where people from the altiplano exchange dried meat and puna
crops such as potatoes with other groups in mid-altitudes for maize, beans, and
other local crops; they also trade with coastal groups for dried fish, seaweed, and
low-altitude crops. After trading on the coast, the altiplano people return to their
villages, collecting their local products along the way. No doubt this is an
ancient, probably pre-Inca practice.
Andean peoples also developed another mechanism to meet the challenges of
distant resources. In this system, villages in one zone sent family members to
live in another zone to produce the necessary crops. The Incas expanded this
concept to include entire villages that they moved to grow crops of interest to
them (see Labor Service).