Ancient farming system and campesino livelihoods at risk in Mexico City

XOCHIMILCO, Mexico — In the 70 years Miguel del Valle has worked on his family’s chinampa in Xochimilco, a neighborhood in the south of Mexico City, he has witnessed a huge change in the environment and the attitudes of his neighbors.

“Xochimilco was always famous for its vegetables and flowers,” the 80-year-old farmer, also known as a chinampero, told Mongabay, while looking out at the rows of lettuce, radish and broccoli planted across almost every inch of his family’s 3.5-hectare (8.6-acre) chinampa. “Now, there is none of that. And that makes me sad.”

Chinampas are an agricultural system developed by the Aztec Empire in shallow lakes or marshes in the southern valley of what is today Mexico City. They consist of elevated, narrow mounds of earth used as fields for farming, surrounded by water canals that are connected to ditches. The mounds are constructed with mud excavated from the water channels and fences made of ahuejote (Bonpland willow, Salix bonplandiana), interwoven with reeds and branches of other plants.

The ground beneath del Valle’s feet is one of the few chinampas still used to grow food. Many chinamperos have left the fields to find work in the city, to improve their economic situation or escape the host of environmental issues that threaten their livelihoods. Some people have converted their chinampas to football fields and festival grounds. Tourists visit Xochimilco to tour the waterways in brightly colored boats known as trajineras, which have become an unavoidable feature of the canal landscape and key source of income for locals, despite the environmental consequences. As a result, according to researchers at the National Autonomous University of Mexico, there are now 16,000 abandoned chinampas in Xochimilco, and only 17% are considered active.

An increase in the rejection of chinampa culture has also put chinampero ancestral knowledge under threat. Traditional cultivation techniques such as milpa, an ancient method of growing a wide range of crops in a limited space, as well as knowledge about how to maintain the chinampa have been passed down for thousands of years. But now, there are fewer people to relay that information to and, as the tradition is transmitted orally, there’s never been any form of record-keeping.

“People don’t want to know about the campo [countryside],” says Sonia Tapia, agricultural team lead for Arca Tierra, an organization that focuses on the preservation of the chinampa system. “Knowledge has been lost. There are many things we would like to know about how things were done before, how they resolved issues, but there is no one to explain it to us anymore.”

Del Valle learned these skills from his grandfather, father and uncles. And now, he must share this knowledge with his children. But the difficulties he faces today are very different to those of his ancestors.

Pressures on the last remaining Aztec-era agricultural systems

Threatened by the rapid growth of Mexico City and its suburbs, the chinampas have decreased significantly in number since the second half of the 20th century. During this time, Mexico City’s population exploded, which resulted in a series of environmental problems for the last remaining chinamperos. An estimated 25% of the wetlands have been urbanized, a transformation that has caused water contamination, land degradation and a loss of biodiversity from the clearing of native vegetation and dumping of sewage and agricultural residue.

Xochimilco, which is a protected natural area, is home to 2% of the world’s biodiversity. Throughout the complex network of canals that surround the chinampas, scientists have recorded 1,700 plants, 320 bird, 57 reptile, 70 mammal and 20 amphibian species. More than 250 of these species are endemic, including the Aztec rail (Rallus tenuirostris) and volcano rabbit (Romerolagus diazi), which are both threatened with extinction.

In the 1970s, the government introduced nonnative wildlife to Xochimilco, such as the carp (Cyprinus carpio) and tilapia (Oreochromis niloticus), which are considered invasive species and have contributed to the extinction of several endemic species. Many others remain under threat, such as the axolotl (Ambystoma mexicanum) and the Chapultepec splitfin (Girardinichthys viviparus). Around 55% of the endemic species of Xochimilco are considered under some state of conservation.

“The carp has destroyed a lot of habitats and a lot of fauna endemic to Xochimilco,” says Óscar Camacho Flores, founder of the national civil organization Preservacf A.C. “It has become a pest and a very serious problem for Xochimilco. Chinampas have been destroyed, and the fauna. The lakes are full of the plague.”

Besides its designation as a national protected area, Xochimilco is listed as a UNESCO World Heritage Site, an FAO Site of Agricultural Importance, and a Ramsar wetland of international importance. And yet, most of the water in Xochimilco’s 150 kilometers (93 miles) of canals is contaminated due to agrochemical runoff, the unregulated tourism industry and discharges from irregular settlements in the area.

According to data from the Institute of Democratic and Prospective Planning, a Mexican government body, the Xochimilco conservation area hosts 308 irregular settlements that contain 17,803 homes for 133,523 people in a 569-hectare (1,406-acre) area. There’s little information from the government or other sources for why people choose to live here or why they continue to return, despite previous fines and evictions. One government report published in 2022 stated that the irregular settlements are a consequence of population growth. Camacho tells Mongabay that the lakes in this area are the most contaminated because the people who live here don’t have proper waste disposal and therefore dump directly into the water.

“The chinampa area is considered a conservation zone, you cannot live in that area, but the government has allowed the settlements to grow,” he says. “It has not protected the conservation area at all. It has no systems or programs for cleaning the canals, and no one is monitoring whether a person builds a house or not.”

The Xochimilco’s mayor’s office, the ministries of culture and environment, the Mexico City water board and the National Water Commission didn’t respond to Mongabay’s multiple requests for comment.

Canals running dry

Del Valle stands on a wooden bridge and looks down at the narrow canal that runs through his chinampa. This, he says, is one of the few clean channels in the area. He points at the aquatic plants lining the banks below and says these species, such as bulrush (Schoenoplectus americanus) and broadleaf cattail (Typha latifolia), were brought in to act as biofilters.

The rest of the water in the area is contaminated, he says. His son, Javier del Valle, tells Mongabay there’s no vision to protect the area. “No designation [such as World Heritage Site] has been able to counteract the environmental problems that exist both in the water and in the trees,” he says. “In most of this ecosystem, the water is not treated and is therefore of poor quality.”

In 1950, when Xochimilco’s canals began to run dry due to overdrawing of the water to supply the city, the government began piping in treated sewage water from four treatment plants. However, according to researchers, local organizations, chinamperos and other residents, the water from the treatment plants often arrived contaminated.

This, in combination with other factors such as discharges from the irregular settlements, has reduced the water quality in the canals — an issue that greatly impacts the chinampas, biodiversity and human health.

Although water scarcity isn’t a new problem for residents of Mexico City, for several months recently the supply crisis has been exacerbated by severe drought. Extremely low rainfall and historically high temperatures have added additional stress to a water system already struggling to cope with the demand.

“The drought has manifested in all the channels,” del Valle says. “Many canals are very, very low in water and it is no longer possible to travel with the trajinera or canoe. That is another risk here in Xochimilco. Without its canals, Xochimilco is finished.”

This problem also affects food production, as chinamperos are unable to irrigate their crops as frequently, which they need to do in these drought conditions. On Arca Tierra’s chinampa, for example, which is named Chinampa del Sol, Tapia demonstrates the impact that the lack of rain has had on the soil.

She kneels on the ground and scoops up a handful of earth. The soil looks like loose white rock. This, she says, is soil salinization, which is what happens when water evaporates from saline soils. When there’s not enough rain, the salt in the water is left behind to accumulate on the soil surface, which further inhibits water absorption and limits the growth and productivity of plants.

“When there is no water flow, it causes that crust to harden and reduces the permeability of the soil,” says Diana Laura Vásquez Mendoza, a researcher at UNAM. “When that happens, like right now with the issue of the rain, it affects production.”

To preserve the ecosystem and the cultural richness of the area, chinamperos, local organizations, academic institutions and independent citizens have carried out a series of diverse actions to restore the chinampas and prevent further environmental damage.

“Successful conservation of a species, including the axolotl or any other species, also relies on the recovery and conservation of its habitat,” says Mendoza, who notes that the annual maintenance of an axolotl colony costs 100,000 pesos (about $5,700) and of a “refuge chinampa” to host the amphibians another 100,000 pesos. “It’s expensive.”

“My greatest desire is to preserve all this and involve my family, such as my children and grandchildren,” del Valle says. “I don’t like that the land is abandoned, and I wish my neighbors would do a bit to conserve all this, the nature and the environment.”

Featured image: Many people visit Xochimilco for its cultural and ecological value, touring the canals in colorful gondola-like boats called trajineras. However, poor regulation of the tourism industry, which is one of the region’s main economic activities, has added to the area’s environmental problems and brings more pollution to its waterways. Image by Aimee Gabay.

Citations:

Ebel, R. (2020). Chinampas: An urban farming model of the Aztecs and a potential solution for modern megalopolis. HortTechnology, 30(1), 13-19. doi:10.21273/HORTTECH04310-19

Medina, F.-X., Vázquez-Medina, J. A., Covarrubias, M., & Jiménez-Serna, A. (2023). Gastronomic sustainable tourism and social change in World Heritage Sites. The enhancement of the local agroecological products in the chinampas of Xochimilco (Mexico City). Sustainability, 15(22), 16078. doi:10.3390/su152216078

Eakin, H., Shelton, R. E., Siqueiros-Garcia, J. M., Charli-Joseph, L., & Manuel-Navarrete, D. (2019). Loss and social-ecological transformation: Pathways of change in Xochimilco, Mexico. Ecological and Society, 24(3). doi:10.5751/ES-11030-240315

Merlín-Uribe, Y., González-Esquivel, C. E., Contreras-Hernández, A., Zambrano, L., Moreno-Casasola, P., & Astier, M. (2013). Environmental and socio-economic sustainability of chinampas (raised beds) in Xochimilco, Mexico City. International Journal of Agricultural Sustainability, 11(3), 216-233. doi:10.1080/14735903.2012.726128

Zambrano, L., Valiente, E., & Vander Zanden, M. J. (2010). Food web overlap among native axolotl (Ambystoma mexicanum) and two exotic fishes: carp (Cyprinus carpio) and tilapia (Oreochromis niloticus) in Xochimilco, Mexico City. Biological Invasions, 12, 3061-3069. doi:10.1007/s10530-010-9697-8 doi:10.1007/s10530-010-9697-8

Domínguez Alfaro, N. N., Guerra Ramírez, D., Rodríguez Palacio, M. C., & Castilla Hernández, P. (2023). Xochimilco Lake, Mexico. The importance of its preservation: Challenges and opportunities. In 18th World Lake Conference: Governance, Resilience and Sustainability of Lakes for a Better Society (pp. 559-571). Guanajuato, Mexico. Retrieved from https://www.researchgate.net/publication/368574623_Xochimilco_Lake_Mexico_The_importance_of_its_preservation_challenges_and_opportunities

Figueroa, F., Puente-Uribe, M. B., Arteaga-Ledesma, D., Espinosa-García, A. C., Tapia-Palacios, M. A., Silva-Magaña, M. A., … Zambrano, L. (2022). Integrating agroecological food production, ecological restoration, peasants’ wellbeing, and agri-food Biocultural heritage in Xochimilco, Mexico City. Sustainability, 14(15), 9641. doi:10.3390/su14159641

Feedback: Use this form to send a message to the author of this post. If you want to post a public comment, you can do that at the bottom of the page.