Chinampas are raised-bed agricultural systems invented by the Aztecs. Built in low, marshy areas, the chinampas were elongated rectangular islands built up above the water level, with canals flowing between them. Each island was constructed by building retaining walls woven from posts and branches. The soil between these walls was then built up by adding soil excavated from the canals, and willow trees were planted along the walls to reinforce them with their mostly vertical root system. The final height of the chinampa would be roughly one meter above the water level.
The crops grown on the chinampas were polycultures, such as the squash-beans-maize complex (Upper Sonoran Agricultural Complex) and the amaranth-bean-cassava-maize-pepper complex. Various trees, such as the Mexican cherry and hawthorn, were also grown, and animals were often kept in corrals on the islands. Fish and/or water hyacinths were grown in the canals.
The chinampa is a textbook example of a regenerative agricultural system, in which every element contributes to the final yield and gives something back to the system so that resources are continually renewed. The canals would be periodically dredged, their sediments (including nutrient-rich fish waste) going to the chinampas to restore lost nutrients and soil. The livestock ate agricultural waste, and provided manure for the crops and protein for the farmers. The polycultures themselves were selected for maximum sustainability as well as low maintenance requirements. The chinampas needed no water or nutrient input, and could answer all of the farmers’ needs with minimal environmental impact. The water flow through the chinampas was virtually unchanged from the undeveloped state. While many agricultural systems can claim similarly low impact, the chinampa system was productive even compared to modern monocultures, at one time providing ½ to 2/3 of the food for the 150,000-200,000 residents of Tenochtitlan.
- ”Regenerative Design for Sustainable Development”, John Tillman Lyle 1994