Today many of the terraces Gaoxigou laboriously hacked out of the loess are reverting to nature. In what locals call the "three-three" system, farmers replanted one-third of their land—the steepest, most erosion-prone slopes—with grass and trees, natural barriers to erosion. They covered another third of the land with harvestable orchards. The final third, mainly plots on the gully floor that have been enriched by earlier erosion, was cropped intensively. By concentrating their limited supplies of fertilizer on that land, farmers were able to raise yields enough to make up for the land they sacrificed, says Jiang Liangbiao, village head of Gaoxigou.