The 2,000-year-old Banaue rice terraces in the Philippines, which are already under threat from poor irrigation, neglect, and cultural change, have met a new menace - giant earthworms.
The ancient terraces, dubbed the "eighth wonder of the world" by the Philippines Department of Tourism, are being slowly eroded with the help of the worms, which grow up to 18 inches long.
The narrow terraces, which rise like steps up the hillsides, have been declared a World Heritage site by Unesco and are the No. 1 tourist destination in the northern Philippines.
Christopher Pagadut, project development officer of the Rice Terraces Commission (RTC), has conducted a study on the impact of the worms on the terraces in Banaue, northern Luzon, about 250 kilometers (155 miles) north of Manila.
The average number of worms per spade full of soil is 16 to 21, Mr. Pagadut says. "The worms bore deep within the terrace stones, which produces an effect like a hole in a dike. When the rains come in the rainy season, they wash away the soil, leading to the collapse of the wall and the terrace," Pagadut says. It only takes a week of rains to destroy a 1,000-year-old terrace.
Pagadut is looking at methods to control the worms that will not damage the environment. The worms are not indigenous. They arrived after World War II it is believed when higher yield strains of rice were introduced.
Planting sunflowers, treating the soil with a solution of soap powder and salt, and using pesticides have already been tried. However, the chemicals cause environmental damage, and the sunflowers have had only a limited effect.
The most effective method so far has been an ancient pest-control system used by the Ifugao tribes, who are believed to have begun building the terraces between 200 BC and AD 100.
This involves mixing three types of forest vines with water. The soil is treated with the mixture during planting. However, even this method is unsuitable because the number of vines available in the rain forest is diminishing rapidly.
The extent of the problem was such that in 1994, President Fidel Ramos ordered the setting up of the RTC (comprising governmental agencies and chaired by the Department of Tourism Secretary Mina Gabor) to search for a workable maintenance program.
"They are already starting to deteriorate. Thirty years ago the grandeur of the rice terraces was magnificent. In 20 year's time, we do not know," says Banaue Mayor Tito Candelario.
Giant earthworms are undoubtedly a problem, but the main threat to the terraces is the the so-called "brain drain" of young Ifugaos who desert the uplands in favor of the bright lights of the cities.
Rice farming is labor intensive, and it reaps relatively low financial returns. "When you can get a high-paying, white-collar job working in the city, who wants to push a plow in the mud all day?" asks Lauris Anudon, RTC project evaluation officer.
The young Ifugaos are not interested in going back to work in the fields after they've finished college. The work is hard, and most terraces are too narrow for a water buffalo to plow, Mr. Anudon says. Another major problem is the lack of irrigation. Illegal logging and systematic deforestation have exacerbated the problem in a country that already suffers chronic water shortages in the dry season.
Anudon adds that the terraces are not as cost effective as the lowland rice fields. "Unlike the lowlands, where you can have two crops a year, the terraces can only sustain one. There is not enough water for irrigation because the forests have been logged and the watershed has been destroyed," he says.
Antonia Kindipan helps her neighbors farm their plot. Her husband left the province to seek work elsewhere. "You can't grow enough food to live on for a whole year. That's why many people are leaving to work in other places," she says.
Ken Fischer, deputy director general for research at the International Rice Research Institute, says traditional work methods must change if rice cultivation is to stay the dominant culture.
"The image of a water buffalo plowing a field may be aesthetically pleasing to the tourist, but it is no solution to the problems of increasing rice yields or making rice cultivation more attractive and profitable for the farmer," Mr. Fischer says. Anudon points out that many farmers are turning to commercial cash crops like cabbages and beans. They can be harvested within 45 days, whereas rice takes six to seven months to harvest.
This year, the RTC implemented a nine-point plan to maintain the terraces. The farmers are being encouraged to supplement their income through traditional means, such as loom weaving. They are also being advised to cultivate more cash crops like mushrooms, when they are not working in the rice fields.
Schools in the area are being encouraged to teach Ifugao culture and forestry, and agricultural college students have field placements at the terraces.
If these methods cannot halt the decline of the terraces, private money may be needed, says Ms. Gabor. She is looking into charging tourists to visit the sites. That way, she says, "the terraces can directly benefit from the one aspect of their long history which is actually flourishing - tourism."