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一、试验区自然条件试验布设在陕北安塞县水土保持试验区的县南河流域,侵蚀地貌属黄土丘陵沟壑区第2副区。流域面积50.6平方公里,沟壑密度每平方公里4.4公里。地面坡度从上向下分为4类:1、梁峁顶部平缓,一般3—10°;2、梁峁坡较陡,一般15—25°,有的达30°;3、沟坡最陡,多为25—35°;4、塌地与沟台地也较缓,为5—15°。其中0—15°的占1.6%,15—25°的占22.4%,25—35°的占50%以上,35°以上的占21.4%。地面组成物质大都是黄土,沟床和沟岸有岩石和红土露头。海拔高1,010—1,400米。年平均气温8.8℃,极端最低气温-23.6℃。平均无霜期159天,≥10°的年平均积温3,160.2℃。年平均降水量553毫米,但分布不均,主要集中在6—9月,其中
First, the experimental area of natural conditions The test is located in Ansai County, Shaanxi Province, soil and water conservation pilot counties in the South River Basin, the erosion of the loess hilly and gully area is the second sub-district. Basin area of 50.6 square kilometers, gully density of 4.4 kilometers per square kilometer. The slope of the ground is divided into four categories from top to bottom: 1, the top of the beam is smooth, usually 3-10 °; 2, the beam slope is steep, generally 15-25 °, some of up to 30 °; 3, , Mostly 25-35 °; 4, land and ditch also slow, 5-15 °. Among them, 0-15 ° accounted for 1.6%, 15-25 ° accounted for 22.4%, 25-35 ° accounted for more than 50%, 35 ° or more accounted for 21.4%. The composition of the ground is mostly loess, ditch bed and ditch shore rock and clay outcrop. 1,010-1,400 meters above sea level. The annual average temperature of 8.8 ℃, extreme minimum temperature -23.6 ℃. The average frost-free period of 159 days, ≥ 10 ° average annual temperature of 3,160.2 ℃. The average annual rainfall of 553 mm, but unevenly distributed, mainly concentrated in June-September, of which