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旱地农业目前在世界范围内存在的主要问题是水分的制约和土壤的制约。水分制约主要表现为:①降水量少。由于自然降水量少,不能满足作物正常生长所需要的水分供给量,限制了作物的正常生产;②降水分布不均。由于降水分布不均,与作物生长的需水分布不吻合,从而导致一些自然降水的浪费,另一方面又表现出作物供水不足的两不利现象,其结果也限制了作物的正常生产;③降水变率大。由于年际间降水的不稳定性,极易导致干
The main problems that exist in dryland agriculture in the world at present are the restriction of water and soil. Moisture constraints mainly as follows: ① less precipitation. Due to the small amount of natural precipitation, it can not meet the requirement of water supply for the normal growth of crops, which limits the normal crop production; (2) There is uneven distribution of precipitation. Due to the uneven distribution of precipitation, which is not consistent with the distribution of water demand of crops, resulting in some wastes of natural precipitation and on the other hand shows two unfavorable phenomena of crop water supply, which also limits the normal crop production. ③ Precipitation Variable rate. Due to the instability of precipitation during the year, it can easily lead to dryness