Chinampa (Nahuatl: chināmitl [tʃiˈnaːmitɬ]) is an agricultural method used in Mesoamerica. It involves creating small, rectangular plots of fertile land on shallow lake beds in the Valley of Mexico. The word "chinampa" comes from Nahuatl, meaning "in the fence of reeds." These plots are built on wetlands, such as lakes or freshwater swamps, and their shape helps keep the soil moist. This technique was widely used in Lake Xochimilco. In 2018, the United Nations recognized chinampas as a Globally Important Agricultural Heritage System.

During the post-classic and colonial periods, chinampas raised questions about farming and political growth. After the Aztec Triple Alliance formed, conquering city-states like Xochimilco became a key strategy for expansion. Before this, farmers in Xochimilco and Chalco built small chinampas near their homes. The Aztecs did not create chinampas but expanded their use on a large scale. Sometimes called "floating gardens," chinampas are artificial islands made by weaving reeds with stakes underwater, forming underwater fences. Soil and plants were then added to these fences until the top of the soil reached the water’s surface.

When building chinampas, a drainage system was also created. This system had multiple uses. Ditches were dug to allow water and sediments (including waste) to flow. Over time, mud would collect in the ditches and be removed to add to the chinampas. Soil from the lake bottom was rich in nutrients, helping to fertilize the plots. Adding nutrients to the soil ensured good harvests. A study by researchers found that cultivated chinampa soil had more types of bacteria than non-cultivated soil. The bacteria helped improve soil nutrients, and some types were linked to the roots of plants growing in the chinampas.

Evidence from Nahuatl wills from the late 17th century shows that chinampas were measured in units called matl (1 matl = 1.67 meters), often grouped in sets of seven. A scholar used the Codex Vergara to estimate that chinampas were usually about 30 meters long and 2.5 meters wide. In Tenochtitlan, chinampas ranged from 90 meters by 5 meters to 90 meters by 10 meters. They were built by marking the lake bed and fencing areas with wattle (woven branches). Mud, lake sediment, and decaying plants were layered inside the fences until the land rose above the water. Trees like āhuexōtl (Salix bonplandiana, a willow) and āhuēhuētl (Taxodium mucronatum, a cypress) were planted at corners to hold the chinampas together. Some chinampas had ditches between them, allowing plants continuous access to water. This made crops independent of rainfall. Chinampas were separated by wide channels for canoes to pass through. These well-watered plots produced up to seven harvests per year. Chinampas were used in pre-colonial Mexico and Central America. Evidence suggests that the Nahua settlement of Culhuacan, near Lake Texcoco and Lake Xochimilco, built the first chinampas around 1100 C.E.

History

The oldest known chinampa fields date back to the Middle Postclassic period, between 1150 and 1350 CE. These floating gardens were mainly built in Lakes Xochimilco and Chalco, near natural springs along the southern shores of those lakes. The Aztecs worked to control these areas through military actions and, according to some studies, used large-scale efforts to expand the chinampa system. Evidence suggests that the government may have played a role in this expansion, a theory sometimes called the "hydraulic hypothesis." This idea connects to the concept of a "hydraulic empire," which is an empire that gains and keeps power by managing water resources. Some evidence supports government involvement, such as the need for large amounts of labor and materials to build, turn, and maintain the chinampas. However, arguments about government control depend on the belief that dikes were needed to control water levels and keep saltwater from Lake Texcoco away from the chinampa area. This idea is reasonable, but there is also evidence that chinampas worked before dikes were built. Some experts suggest the dikes were added to greatly increase the size of the chinampa system.

Chinampa farms surrounded Tenochtitlan, the Aztec capital, which grew larger over time. Smaller chinampa farms have also been found near Xaltocan, an island city, and on the eastern side of Lake Texcoco. During the Spanish conquest of the Aztec Empire, many chinampas were abandoned after dams and water gates were destroyed. However, some lakeshore towns continued using chinampas until the end of the colonial period because growing crops on them required a lot of labor, which made it less appealing for Spanish settlers to take over.

The Aztecs built Tenochtitlan on an island around 1325. As the city expanded, it ran out of space to grow. As the empire grew, more food was needed. At times, this meant taking over new land, and at other times, it meant expanding the chinampa system. This expansion allowed chinampas to grow multiple crops each year, which helped supply food. Historical records suggest that farmers paid a relatively small amount of tribute compared to others, as their annual tribute may have been only a small part of what was needed locally.

Scholars have studied how much Tenochtitlan relied on chinampas for its food supply.

Crops grown on chinampas included maize, beans, squash, amaranth, tomatoes, chili peppers, and flowers. Maize was planted using a digging stick called huictli, which had a wooden blade on one end.

The word chinampa comes from the Nahuatl language, meaning "square made of canes" and the Nahuatl word for "place." Spanish documents sometimes called them camellones, meaning "ridges between rows." However, a Franciscan priest named Fray Juan de Torquemada described them using the Nahuatl term chinampa, saying, "Without much trouble, the people plant and harvest their maize and greens because there are ridges called chinampas; these were strips built above water and surrounded by ditches, which makes watering unnecessary."

Chinampas are shown in Aztec picture books, such as the Codex Vergara, Codex Santa María Asunción, the Uppsala Map, and the Maguey Plan (from Azcapotzalco). In written Nahuatl records from the late 1500s, The Testaments of Culhuacan mentions chinampas as property that people left to their heirs in wills.

Today, parts of the chinampa system still exist in Xochimilco, a southern area of Mexico City. Chinampas have been promoted as a model for modern farming that protects the environment, though some sources disagree about how well this model works. For example, one researcher noted that efforts in the 1970s to use chinampas among the Chontal Maya people failed until plans were changed to better match the Chontal Maya’s needs.

Construction

According to Antonio Vera from the UH Hilo website, chinampas had two types: inland and irrigated. Inland chinampas were built along the edges of water, while irrigated chinampas were constructed on water. The structure of chinampas involved creating shallow land near the water’s edge and surrounding this area with wooden posts from a common wetland tree called ahuejote. As Mexico became more urbanized, this traditional method was no longer used, and new challenges arose due to the growth of cities.

Modern chinampas

As of 1998, chinampas are still found in San Gregorio, a small town east of Xochimilco, as well as in San Luis, Tlahuac, and Mixquic. These gardens were built and carefully maintained from the Postclassic Period through the Spanish conquest. Many of these plots of land still exist and are used today for farming.

Some chinampas have been left to grow wild by modern farmers. A few farmers still use canoes to work the land, but many now rely on wheelbarrows and bicycles for transportation. In areas like San Gregorio and San Luis, some fields have been intentionally filled in. As canals dry up, some fields naturally connect. Although these areas are no longer used for their original purpose, they are often used to grow food for cattle.

Other fields, whether dried or surrounded by canals, produce crops such as lettuce, cilantro, spinach, chard, squash, parsley, coriander, cauliflower, celery, mint, chives, rosemary, corn, and radishes. The young leaves of quelites and quintoniles, which are often mistaken for weeds, are grown and collected for use in sauces. Flowers are also grown on these plots. Some chinampa fields are used as places for tourists to visit.

• Example of a modern-day chinampa
• One of the remaining chinampas in Xochimilco
• Example of cattle feeding on grasses from dried chinampa land

Although many local farmers are pleased to return to traditional farming methods, they face challenges. During the Spanish conquest, many lakes were drained, reducing the area’s ability to grow food, such as the lake at Xochimilco. In 1985, an earthquake damaged several canals. Other challenges include limited water supply, pesticide use, climate change, urban growth, and water pollution caused by untreated sewage and toxic waste.