Mexicans try to save aztec-era farming beds

Five 100 years on, it still takes a canoe to reach the fields that fed this city when it ruled a great empire.

On the map, Xochimilco's gardens are a tiny wedge of green in the southern reach of the Mexican capital's expanding urban sprawling. Along the area's maze of canals, the raised farming beds are the last life vestige of the city's Aztec past.

Anastasio Santana still farms here, growth herbs and veggie on two hectares, or five acres, surrounded by water. Tall willow tree trees abut the canal that flows past his house and fields. Instead of the city, he hears bird calls.

But he is 50 years old and fears that his is the last coevals to grow food here. "People used to plant, but now they get a hold of a job with the authorities and they leave," he said.

although the Spanish conquered the Aztecs and set about draining the vast lake basin at the centre of the vanquished empire, the canals and their raised farming beds, called chinampas, have managed to survive.

But they are under siege. Scattered among some 180 kilometers, or 110 miles, of transmission channel may be no more than an estimated 1,000 chinamperos, as the farmers are called, raising crops with traditional methods.

One of them, Rigoberto González, dredges mud from the canal bed with a long-handled net to create a baby's room for his seeds. He grows boodle, cilantro and rocket, irrigated by the canals. It is so fertile here that he can crop five times a year. But the work is labor-intensive and it cannot compete with the more mechanized agriculture.

"The job is, we don't have a marketplace," said Dionisio Eslava Sandoval, a chinampero who leads a small group of farmers, including González, in seeking ways to earn enough from their farming to keep doing it. More than market forces are working against the growers. The ecosystem that supports the chinampas, a mat of reeds and their roots that is loaded with mud and plant waste, is fragile. For a hundred years the city has been diverting the natural springs that fed the canals. Instead, semi-treated wastewater from a city treatment plant flows in, along with organic waste and bacteria.

Illegal settlements on the chinampas lack proper sewage lines, and their waste also goes into the canals.

Misguided efforts at creating fisheries 30 years ago introduced carp and tilapia, which have driven away native species, including a small type of salamander called the axolotl. Prized for its meat and its medicinal qualities, the axolotl is a symbol of the lake and it is close to extinction in the wild.

Working in cooperation with the farmers, Luis Zambrano, a biologist at the National Autonomous University of Mexico, is trying to conserve the axolotl.

His team hopes to place in the canals axolotls that the farmers have bred locally. Santana has dug a trial ditch alongside his field to protect the amphibian from its nonnative predators.

At first glance, the area of Xochimilco where González and Santana work seems to be safe. White herons stand at the canals' edges.

Farmers till crops on a few chinampas. The fields are green. The chinampas lie deep within Xochimilco's protected area, about 25 square kilometers, or 10 square miles.

In several ways, Xochimilco is healthier than it was 20 years ago, when Unesco designated it a world heritage site. By that time, it had been all but abandoned, its canals fetid, sewage buried in the sediment. The city even dumped rubble from the 1985 earthquake in parts of Xochimilco.

In the early 1990s, a $2 million investment from the federal government created a drainage outlet, allowing a flow of water that began to wash out some of the contaminated sediment. Migratory birds returned.

But there are signs of decay. Across the canal from González's chinampa, another has been abandoned to grass, its edges beginning to crumble into the water. Instead of farming food crops using traditional methods, most of Xochimilco's farmers have switched to greenhouses, where they grow high-priced ornamental plants with chemical fertilizers and pesticides.

And although the farmers say the canal water is clean enough to irrigate their crops, tests by a team from the national university show that it is not.

"It is a state of emergency," said Marisa Mazari, who led the testing team. "We're going from bad to worse because the urban growth continues unbraked.

"I still think there is a part that can be rescued as a productive aquatic system, but we have to move now."

None of that seems obvious to the thousands of families that flock to Xochimilco for weekend excursions to ride colorful flat-bottomed boats along the outer edges of the canals' labyrinth. Women in canoes pull up offering tacos and soft drinks. Mariachis float alongside. On the banks, though, makeshift houses and rudimentary swing sets are evidence of the city's encroachment.