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提高自然降雨经济效果的关键,是用好自然降雨,使其充分发挥对农业增产的作用。这是中纬度干旱、半干旱类型地区,当前农业增产的战略性问题。中纬度干旱、半干旱类型,也叫大陆型或欧亚大陆草原型,主要分布在北半球,南半球面积较小。我国绝大多数干旱地区都属于这种类型。其降雨量,下限通常规定在250毫米年雨量的等雨量线上,其上限规定在450—550毫米之间,个别地区也有高达600毫
The key to improving the economic effect of natural rainfall is to make good use of natural rainfall so as to give full play to its role in increasing agricultural output. This is a strategic issue of increasing agricultural output in arid and semi-arid regions of the mid-latitude. Mid-latitudes arid and semi-arid types, also known as continental or Eurasian grassland type, are mainly distributed in the northern hemisphere and smaller in the southern hemisphere. Most arid areas in our country belong to this category. Its rainfall, the lower limit is usually provided in the rainfall of 250 mm annual rainfall line, the upper limit between 450-550 mm, some areas have up to 600 milli