Floating Gardens of Mexico

A system of shallow basins forms the floor of the mountain-girt plateau known as the Valley of Mexico. This area was the heartland of the Aztec empire. Its capital, Tenochtitlan, stood on an island in an embayment of Lake Texcoco. South of this area a subdivision of the valley known as the Xochimilco-Chalco Basin exists. The bottom of this basin is comprised of approximately 520 square miles of flats. Until recently, when the completion of drainage works caused the destruction of most of the area, a continuous tract of marshes, swamps, and lagoons extended on these bottoms. From the 14th and 15th centuries, garden plots raised above water have been built on these swamps.

These artificial islands, known as chinampas, were constructed of layers of mud and vegetation within the shallow fresh water lakes. This technique of land reclamation reached its maximal development in the 16th century. Almost all of Lake Xochimilco was converted to chinampas by the early part of the 16th century. The Aztec even converted a large bay of saline Lake Texcoco into a freshwater lake by a system of sluiced dikes and spring-fed aqueducts, and covered it with chinampas. The rich organic soil and readily available moisture, combined with techniques of fertilization and the use of seed beds, converted the lakes into a major agricultural resource. Chinampa cultivation represents the final stage of ecological adaptation of the Mesoamerican farmer to the Basin of Mexico. By 1519, the combination of chinampa agriculture, canal and floodwater irrigation, and terracing supported the densest population in the history of the culture area.

Recent archaeological investigations, which focused on researching aerial photographs and the inspection of on-the-ground traces of the old field system, have revealed that the extent of the raise plots was much greater in the Aztec period than had been recognized. In addition, archaeological data were obtained to substantiate the descriptions left by 16th-century witnesses of native land-reclamation records.

The natives' methods of expanding farmland over swamps and lagoons in the Valley of Mexico were described by a number of early Spanish Colonial writers from the 16th century onward. In freshwater lagoons, one wrote, the Indians "without much trouble plant and harvest their maize and greens, for all over are ridges called chinampas; these are strips built above water and surrounded by ditches, which obviates watering."

The pattern for laying out these plots and the principles of this farming system were also outlined in the 16th-century reports: "they make garden lots...carrying in canoes sod cut in the mainland, to heap it up in shallow waters, thus forming ridges from 3 to 4 varas (8 to 11 feet) wide and raised half a vara above the water; a farm has many of these ridges and the farmers circulate in their canoes between them, to tend the crops"; and, "they set maize seedbeds on the chinampas and they transplant the seedlings, which is a thing peculiar to that country."

Seedlings were also started on floating foundations, according to another witness. The movable nurseries were "20 to 30 feet long and as broad as the farmer deems convenient, laid on rush, cattail, and sward; on these they set seedbeds for vegetables which are to be transplanted later, and they tow them with ropes from one place to another within the lagoon." The legend of "Montezuma's floating gardens" appears to have arisen through errors of observation made by some witnesses who mistook the movable nurseries for the farm plots.

To keep the plots under continuous cultivation, the ancient chinampa farmers sustained the fertility of the soil by mucking and manuring. Plot building on swamps, permanent irrigation, and the use of fertilizers produced by the ecosystem, and planting in seedbeds were enmeshed in the system of chinampa horticulture.

Although lakeside settlements were numerous and important, archaeological investigations revealed that chinampa tillers dwelt in the middle of the swamps, rather than on the mainland. These settlements were linked to the mainland by a system of causeways. Besides these island towns, the watery landscape was dotted with small communities and dispersed farmsteads set on artificial foundations amid the chinampa plots.

Although the Valley of Mexico included other prime agricultural districts, none seems to have matched the productivity of the continuous zone of chinampa farming in the Xochimilco-Chalco Basin. Archaeologists estimate that the gross area of reclaimed swamps, excluding islands, amounted to more than 46 square miles. Reducing this figure by one-fourth to account for canals and an indeterminate number of interspersed pools, over 22,230 acres of productive soil was built upon natural wastes. The yields of this farming system per unit of tilled land are estimated to be extremely high. The zone may have produced enough food to nourish some 100,000 people.

The creation of farmland over marshes and lagoons represents the ultimate development of the natural resources (via aboriginal technology) in the Valley of Mexico. The expansion of chinampa farming during the 14th and 15th centuries appears to be related to a substantial increase in population. On the eve of the Spanish conquest this heartland of empire greatly outranged in human resources any other center of power within the sphere of Mexican civilization. Late in the 16th century, with the demise of Tenochtitlan and the changes in hydrography due to clumsy attempts at flood control, the garden plots were still farmed by Indians in the outlying wards of Mexico City, the Spanish town rebuilt over the rubble of Tenochtitlan.

The few remaining lush chinampas of Xochimilco still grow crops for Mexico City today, mostly in the form of flowers such as gardenias, hibiscus, and roses. It is a popular spot where families can escape the traffic noise and smog of the city to picnic and relax. The inhabitants of this area still speak the Aztec language and occupy the same land as their ancestors, renewing the chinampas each year by the same methods used in Aztec times. The outlines of former beds may be seen for a considerable distance, since the modern draining of Lake Texcoco has dried up much of the lake area of the Valley of Mexico.

--Hettie Ballweber, MG, 1996

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