The Aztecs fed their capital from 'floating gardens' that don't actually float.
Chinampas are long, narrow fields built up from the bed of a shallow lake, fenced with reeds and piled high with mud and plants. Watered from below and fertilised with canal silt, they could yield up to seven harvests a year. Some still survive in Mexico City's Xochimilco.
Chinampas are often called floating gardens, but they are artificial islands anchored to the lake bed. Farmers staked out a rectangle in the shallows, fenced it with woven reeds, and filled it with layers of mud, lake sediment and rotting vegetation until it rose above the water. Willows and cypresses planted at the corners helped hold them together. Typical plots were long and narrow, around 30 by 2.5 metres according to one estimate, separated by channels wide enough for a canoe.
The design was ingeniously self-sustaining. Because the beds sat among canals, crops had continuous access to water and did not depend on rainfall. The channels gradually filled with nutrient-rich mud, likely including human waste, which farmers dug out and spread on the beds, clearing the canal and fertilising the soil in one job. Modern studies find these cultivated soils rich in bacterial diversity. The yields were extraordinary, with up to seven harvests a year of maize, beans, squash, amaranth, tomatoes, chillies and flowers.
The Aztecs didn't invent chinampas. The earliest securely dated fields are from about 1150 to 1350 CE, and some evidence points to a Nahua settlement at Culhuacan building them around 1100. But after the Aztec Triple Alliance conquered the southern lake cities, they developed the system on a large scale, and chinampas ringed their island capital, Tenochtitlan. How far the state organised this expansion, perhaps with dikes to keep out the salty water of Lake Texcoco, is still debated.
After the Spanish conquest, many fields were abandoned when dams and sluices were destroyed, though lakeshore towns kept theirs. Remnants survive in Xochimilco, and in 2018 the UN recognised chinampas as a Globally Important Agricultural Heritage System. They are often promoted as a model for sustainable farming, though some experts question how easily they transfer to other places.
Source: Wikipedia — Chinampa · Text summarised from Wikipedia (CC BY-SA 4.0)
