subsurface drainage

基本解释

The subsurface pipe drainage came into being just in the metaphase of20th century. It was broadly applied in USA, Japan and Egypt for30~40years.
暗管排水在20世纪中期初步形成，近30～40年在美国、日本、埃及等国家得到广泛应用。
However, when irrigation application decreased by 25% the salt accumulation in root zone will not be obvious and the subsurface drainage flow will decrease by 31.4%.
现状灌溉用水量减少25%时，作物根区没有产生明显的积盐，地下排水量减少31.4%。
Several methods of determining the optimal space and depth of subsurface plastic drainage tubes are explicated and summarized in this paper.
本文介绍了农田塑料暗管埋深和间距的确定方法，并对之进行了评述。