Analysis of information sources in references of the Wikipedia article "Banaue Rice Terraces" in English language version.
Add to that, the loss of interest among the younger generations to farming. They'd rather go down to the cities and try their luck for a more stable income in call centers, real estate and other salary-based careers.
The Banaue Rice Terraces, built by the Ifugaos by hand some 2,000 years ago, is among the country's national cultural treasures and is listed as a UNESCO (United Nations Educational, Scientific, and Cultural Organization) World Heritage Site.