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我国西北、东北西部、华北大部的半湿润易旱地区的面积,约占全国土地总面积的五分之一,这些地区属季风降雨区,降雨多集中在7—9月,冬春干旱。同时年降雨量变化大,也常出现伏旱、秋旱、全年旱和连年旱。干旱是这些地区最主要的自然灾害。干旱使土壤中的有机物质难以分解,土体形不成良好的结构,水土易流
The area of the semi-humid and drought-prone areas in the northwestern, northeastern and western parts of China and most of North China accounts for about one fifth of the total land area of the country. These areas belong to the monsoon rainfall area with rainfall mostly concentrated in the period from July to September and are in winter and spring. At the same time the annual rainfall changes, but also often appear drought, autumn drought, dry and even year-round drought. Drought is the most significant natural disaster in these areas. Drought makes the organic matter in the soil difficult to decompose, soil shape is not a good structure, easy flow of soil and water