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一、提出问题的依据近年来,天祝永丰滩地区降水量显著降低(由1956年的600毫米下降到1974年的410毫米,减少近20％),已明显影响到草原牧草的植物学组成和产量的稳定。尤其在牧草生长发育的初期(5—6月),往往因干旱而导致牧草凋萎,使春乏现象不能及时扭转,严重限制了草原生产能力的发展。因此草原灌溉问题已是草原培育的重大课题。从1970年以来,我们在春季引洪漫灌草原,得到了较好的效果。但由于草原起伏不平,即使在地形平坦,坡度仅1％—3％的滩地上,漫灌有效面积也只有20％—30％,
I. Basis for Proposing the Problem In recent years, the precipitation in Tianzhu Yongfengtan area has dropped significantly (from 600 mm in 1956 to 410 mm in 1974, a decrease of nearly 20%), which has obviously affected the botanical composition and yield of grassland herbage Stable. Especially in the early stage of forage growth and development (May-June), the forage often wilts due to drought, which can not reverse the spring shortage in time, which severely limits the development of grassland productivity. Therefore, the problem of grassland irrigation is a major issue of grassland cultivation. Since 1970, we introduced flood grassland in the spring and got good results. However, due to the ups and downs of grassland, even in the flat terrain, slope of only 1% -3% of the beach, flood irrigation effective area is only 20% -30%