Unification of agricultural fields and mechanization as stated above were difficult in Tanada (on a steep slope), but many rice terraces in the mountains were successfully enlarged thanks to the development of civil engineering technology.
（急傾斜）棚田ではこのような圃場整備や機械化は難しかったが、土木技術の進歩で大規模化に成功した山間地の棚田も多い。