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水分是影响作物产量的一个重要资源条件。即使在农业比较发达的美国,干旱仍是作物低产的一个头等重要因素。据美国农业部的统计,1939至1978年间,不利自然条件使美国作物造成的产量损失中,干旱所占的比值最大,达40.8％,而病害和虫害所占的比值分别只有2.7％和4.5％。在我国及广东省,灌溉条件在很多地区也仍是限制产量的重要因素。因
Moisture is an important resource condition that affects crop yields. Even in the more developed agriculture of the United States, drought is still a top priority for low crop yields. According to the USDA, between 1939 and 1978, the adverse natural conditions led to the largest proportion of the yield loss caused by the U.S. crops, accounting for 40.8% of the total, while the ratio of diseases and insect pests was only 2.7% and 4.5% respectively. . Irrigation conditions in many parts of our country and in Guangdong Province are still an important factor limiting production. because