When Spanish conquistadors first encountered the capital of the Aztec world, Tenochtitlán (now present day Mexico City) they looked at the homes built on floating island structures known as chinampas and dubbed the city “The Venice of the New World.”
At the time of Spanish Conquest, Tenochtitlán was larger than most of the cities in Europe, including Paris and Rome. The population, which was between 15,000 and 20,000, was largely non-farming. To feed this large population, farmers constructed farms directly into the lake districts using the chinampas method.
In this method, farmers (called chinamperos) drove posts into the shallow lake bottom. They wove branches between the posts to construct wattle fencing around the perimeter of the chinampas. After this, chinamperos dredged the lake bottom to pull up nutrient-rich mud and muck. They filled the enclosure of wattle fencing with the mud and muck.
Then farmers planted willow trees along the perimeter to secure the enclosure. The roots of the willows kept the soil from eroding. A chinampas measuring 15-30 feet wide and 300 feet long would take 4-6 men 8 days to build.
To keep fresh water circulating through the farm beds, the Aztec built a series of canals through the chinampas to carry fresh water throughout the farming district. These methods of farming helped local farmers to overcome the limits provided by their environment, which included a dry, arid land, variable rainfall, periodic frosts and low soil fertility.
Chinampas farming has similarities to raised bed gardening, lasagna gardening and hydroponics. The techniques allowed farmers to raise enough crops that they could feed the entire city-state. A chinampas could produce up to 8 times the amount of crop compared to a traditional plot of land.
In present-day Mexico City, plant nurseries still practice the ancient techniques of gardening in canals on these floating islands in the Xochimilco district. The estimated 5,000 chinampas built over Lake Xochimilco are all that is left of the ancient chinampas that once existed throughout Tenochtitlán. They have been a designated UN World Heritage site for over 15 years.
Despite the protection of this designation, the chinampas have been degrading. Urban sprawl, illegal development in the Xochimilco district, draining of the natural aquifers and pollution have all caused the canals in the Xochimilco to drain and have left the water highly-contaminated. Additionally, the canals and chinampas are threatened by non-native species such as water lilies. The problems are so large that the UN has considered removing Xochimilco’s world heritage status.
The image at the top of this article is from http://northeasternpermaculture.wikispaces.com/Educational+Resources
*I planned to post this long before the recent rains flooded most of my home state. I honestly and sincerely hope that no one reading this article is offended by the timing.