修水库是人们开发水利资源,兴利除害的重要措施。水库能降服洪水,灌溉万顷良田。然而,人们在与旱魔作斗争的实践中,还修建了风格迥异的另一种水库,它虽然不象地面水库那样洋洋可观,但其作用却不可等闲视之,这就是“耕层水库”。在旱区,未经改良培肥的土壤,其蒸发量很大,自然降落到土壤中的水分约有25～50％被蒸发掉,留下的水分满足不了作物的需要,所以经常受春旱、伏旱和秋吊的威胁。如何把仅有的降水保住,尽量减少蒸发,这 To repair the reservoir is one of the important measures to develop water conservancy resources, Reservoir can surrender floods, irrigation million square meters of fertile land. However, in the practice of fighting Upland, people also built another reservoir of a very different style. Although it is not as impressive as a surface reservoir, its role can not be ignored. This is called “tillage reservoir” . In arid areas, unmodified fertilizers are highly volatile and about 25-50% of the water that naturally falls into the soil evaporates. The water left behind can not meet the needs of crops and is often affected by spring drought , The threat of summer drought and autumn hanging. How to keep the only precipitation, minimize evaporation, this