However, in the case of Tanada (on a steep slope) in western Japan, the slope would have to be cut away on a large scale if agricultural fields were to be enlarged, and ancillary works including prevention of mudslides on the slope would involve enormous cost, so many of the rice terraces were not enlarged, or were abandoned and degraded.
ただし、西日本の（急傾斜）棚田では、大規模化をしようとすると斜面を大きく削らなくてはならず、のり面の土砂崩れ対策など付帯工事の費用が莫大となるため、大規模化されなかったり、営農放棄されたりして荒廃していくところも多く見られた。