水平梯田是治理坡耕地水土流失的根本措施,也是山区建设高产稳产农田的主要途径。根据一九七二年秦安、徽县等十一个大队典型调查,梯田粮食亩产六百五十三斤,比坡地三百零九斤增产一点一倍,其中洋芋增产一点三倍,高粱增产一点六倍,小麦增产一倍,玉米增产65％,梯田修平后不仅可以每年每亩控制流失二万三千斤水和二千一百斤的肥土,而且可以一次拦蓄一百毫米的暴雨径流,做到水不出田,土不下坡,变“三跑一低”(跑水、跑 Horizontal terrace is the basic measure to control soil and water loss in sloping arable land and also the main way to build high and stable farmland in mountainous area. According to the typical survey of eleven brigades such as Qin’an and Huixian in 1972, the terraced grain yield of 653 kilograms was double that of the slopes of 300 kilograms, of which the potato production increased by one and a half times. The yield of sorghum one and a half times, doubling of wheat and corn yield by 65%. After the terrace is tightened, not only 23,000 pounds of water and 2,100 kilograms of fertilizer can be drained each mu per year, but also one hundred milligrams Storm runoff, so that water does not field, soil is not downhill, change “three running one low” (running water, run