In the struggle to feed booming populations and attract export income, developing countries have increasingly turned to large-scale mechanized farming. In many cases yields have gone up, but often at a cost to the environment. In the search for what's become known as "sustainable agriculture," many farmers are finding that old farming technologies are often more productive and less damaging than modern methods. Matthew Binder traveled to Mexico's Yucatan Peninsula and reports that the government is having little luck switching farmers from traditional methods of subsistence growing to modern cash crops.