Chinampas: An Urban Farming Model of the Aztecs and a Potential Solution for Modern Megalopolis

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• n conclusion, RF such as chinampas, if correctly managed, produce high yields with relatively low inputs

• the chinampa system, which was developed during the time of the Aztecs in the region of Lake Xochimilco, south of Mexico City

• A chinampa is a raised field on a small artificial island on a freshwater lake surrounded by canals and ditches.

• Farmers use local vegetation and mud to construct chinampas. Fences made of a native willow [bonpland willow (Salix bonplandiana)] protect the chinampa from wind, pests, and erosion

• The dominating crops are vegetables and ornamentals

• Complex rotations and associations allow up to seven harvests per year.

• They are also commonly called floating gardens

• Chinampas are considered raised field (RF) systems, which are a type of agriculture consisting of elevated, narrow platforms used as fields surrounded by water canals connected to ditches

• These fields are constructed by digging the canals and mounding the obtained earth on the platforms

• The chinampas of today are situated at an altitude of 2240 m near the lake region of Mexico City, mainly Lake Xochimilco

• Their development was linked to high regional population density and the growth of sizable local urban communities.

• The RF agriculture provided pre-Columbian farmers with better drainage, soil aeration, moisture retention during the dry season, high and long-term fertility, and high productivity per area and input (

• After the conquest, new crops were established, especially vegetables with a high tolerance for moisture such as lettuce (Lactuca sativa) or cabbage (Brassica oleracea var. capitata). The introduced livestock provided manure for fertilization

• Due to the introduction of conventional production techniques in the context of the Green Revolution around 1970, the chinampas of today are significantly altered compared to the Aztec ones

• Between 1989 and 2006, urban land increased from 46.7% to 57.2% of the total area in Xochimilco (not including illegal housing), and the space for chinampas decreased from 7.4% to 2.5%

• Urbanization has caused environmental problems such as forest degradation, erosion, floods, land sinking, pollution of soil and water, reduced water retention and infiltration, and a loss of biodiversity

• n 1950, the local government began supplying treated sewage water for the chinampas because many canals annually run dry. The polluted water caused soil degradation and habitat alteration

• chinampa soils are characterized by considerable aerobic microbial activity and, consequently, high oxygen consumption

• The length of the individual fields varies from 8 to 100 m, and the width varies from 2 to 25 m

• The desired capillary effect determines the optimal dimensions: if the soil water is deficient during certain periods, then narrow fields are more convenient, and vice versa