Chinampa - Ancient Agricultural System of Floating Gardens

Highly Productive and Ecologically Sound Ancient Farms

Chinampa Gardens at Xochimilco
Chinampa Gardens at Xochimilco. Hernán García Crespo

Chinampa system farming (sometimes called floating gardens) is a form of ancient raised field agriculture, used by American communities at least as early as 1250 CE, and successfully used by small farmers today as well.

Chinampas are long narrow garden beds separated by canals. The garden land is built up from the wetland by stacking alternating layers of lake mud and thick mats of decaying vegetation. The process is typically characterized by exceptionally high yields per unit of land. The word chinampa is a Nahuatl (native Aztec) word, chinamitl, meaning an area enclosed by hedges or canes.

Key Takeaways: Chinampas

  • Chinampas are a type of raised field agriculture used in wetlands, constructed of stacked alternating layers of mud and decaying vegetation. 
  • The fields are built with a series of long alternating strips of canals and raised fields. 
  • If properly maintained, by dredging organic-rich canal muck and placing it onto of the raised fields, chinampas are quite productive. 
  • They were seen by the by Spanish conquistador Hernan Cortes when he reached the Aztec capital of Tenochtitlan (Mexico City) in 1519. 
  • The oldest chinampas in the Basin of Mexico date to ca. 1250 CE, well before the formation of the Aztec empire in 1431. 

Cortes and the Aztec Floating Gardens

The first historical record of chinampas was by the Spanish conquistador Hernan Cortes, who arrived in the Aztec capital of Tenochtitlan (now Mexico City) in 1519. At the time, the basin of Mexico where the city is located was characterized by an interconnected system of lakes and lagoons of varying size, elevation, and salinity. Cortes saw agricultural plots on rafts on the surface of some of the lagoons and lakes, connected to the shore by causeways, and to the lakebeds by willow trees.

The Aztecs did not invent chinampa technology. The earliest chinampas in the Basin of Mexico date to the Middle Postclassic periods, about 1250 CE, more than 150 years before the formation of the Aztec empire in 1431. Some archaeological evidence exists showing that the Aztecs damaged some of the existing chinampas when they took over the basin of Mexico.

Ancient Chinampa

Xochimilco Chinampas, Aerial View
Aerial view over Xochimilco traditional agricultural fields Mexico City, March 16, 2015. Getty Images / Ulrike Stein / Stock Editorial

Ancient chinampa systems have been identified throughout the highland and lowland regions of both continents of the Americas, and are also currently in use in highland and lowland Mexico on both coasts; in Belize and Guatemala; in the Andean highlands and Amazonian lowlands. Chinampa fields are generally about 13 feet (4 meters) wide but can be up to 1,300–3,000 ft (400–900 m) in length.

Ancient chinampa fields are difficult to identify archaeologically if they've been abandoned and allowed to silt over: However, a wide variety of remote sensing techniques such as aerial photography have been used to find them with considerable success. Other information about chinampas is found in archival colonial records and historic texts, ethnographic descriptions of historic period chinampa farming schemes, and ecological studies on modern ones. Historical mentions of chinampa gardening date to the early Spanish colonial period.

Farming on a Chinampa

Chinampa Field Scene, Xochimilco
Chinampa Field Scene, Xochimilco. Hernán García Crespo

The benefits of a chinampa system are that the water in the canals provides a consistent passive source of irrigation. Chinampa systems, as mapped by environmental anthropologist Christopher T. Morehart, include a complex of major and minor canals, which act both as freshwater arteries and provide canoe access to and from the fields.

To maintain the fields, the farmer must continually dredge soil from the canals, and redeposit the soil atop the garden beds. The canal muck is organically rich from rotting vegetation and household wastes. Estimates of the productivity based on modern communities suggest that 2.5 acres (1 hectare) of chinampa gardening in the basin of Mexico could provide an annual subsistence for 15–20 people.

Some scholars argue that one reason chinampa systems are so successful has to do with the diversity of species used within the plant beds. A chinampa system in San Andrés Mixquic, a small community located about 25 miles (40 kilometers) from Mexico City, was found to include an astonishing 146 different plant species, including 51 separate domesticated plants. Other benefits include a damping down of plant diseases, compared to ground-based agriculture.

Ecological Studies

Instensive studies in Mexico City have been focused on chinampas in Xaltocan and Xochimilco. Xochimilco chinampas include not just crops such as maize, squash, vegetables, and flowers but small-scale animal and meat production, hens, turkeys, fighting cocks, pigs, rabbits and sheep. In sub-urban spaces, there are also draft animals (mules and horses) used to draw carts for maintenance purposes and take visiting local tourists.

Beginning in 1990, heavy metal pesticides such as methyl parathion were applied to some chinampas in Xochimilco. Methyl parathion is an organophosphate which is extremely toxic to mammals and birds, which negatively impacted the kinds of levels of nitrogen available in the chinampa soils, decreasing beneficial types and increasing those not-so-beneficial. A study by Mexican ecologist Claudia Chávez-López and colleagues reports successful laboratory tests removing the pesticide, lending hope that damaged fields may yet be restored.

Archaeology

Chinampa or Floating Gardens, Mexico (1860 illustration)
Chinampa or floating gardens, Mexico, journey of Leon De Pontelli to Central America, from L'Illustration, Journal Universel 886(35), February 18, 1860. De Agostini / Biblioteca Ambrosiana Getty Images

The first archaeological investigations into chinampa farming were in the 1940s, when Spanish archaeologist Pedro Armillas identified relict Aztec chinampa fields in the Basin of Mexico, by examining aerial photographs. Additional surveys of central Mexico were conducted by US archaeologist William Sanders and colleagues in the 1970s, who identified additional fields associated with the various barrios of Tenochtitlan.

Chronological data suggests chinampas were built at the Aztec community of Xaltocan during the Middle Postclassic period after significant amounts of political organization was in place. Morehart (2012) reported a 3,700–5,000 ac (~1,500–2,000 ha) chinampa system at the postclassic kingdom, based on aerial photographs, Landsat 7 data, and Quickbird VHR multispectral imagery, integrated into a GIS system.

Chinampas and Politics

Although Morehart and colleagues once argued that chinampas required a top-down organization to be implemented, most scholars today (including Morehart) agree that building and maintaining of chinampa farms do not require organizational and administrative responsibilities at the state level.

Indeed, archaeological studies at Xaltocan and ethnographic studies at Tiwanaku have provided evidence that the meddling of the state in chinampa farming is detrimental to a successful enterprise. As a result, chinampa farming may be well-suited to locally-driven agricultural efforts today.

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