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经过多年的治理 ,黄淮海平原大面积盐碱地得到改良 ,但仍有 460万公顷左右的具有障碍因子的中低产土壤 ,这些地区一般相对人少地多 (人均耕地 0 .2～ 0 .3hm2 ) ,热量资源丰富 ,0℃积温 42 0 0～ 5 5 0 0℃ ,无霜期 1 80～ 2 2 0天 ,光照充足 ,年日照为 2 80 0～ 2 1 0 0小时
After years of governance, a large area of saline land in the Huang-Huai-Hai Plain has been improved. However, there are still 4.6 million hectares of middle- and low-yielding soils with obstacles, which are generally less than those with relatively few people (0.2-2.3 hm2 of cultivated land per capita) The heat is rich in resources. The accumulated temperature at 0 ℃ is 42 0 0 ~ 5500 ℃. The frost-free period is 180 ~ 220 days. The sunlight is sufficient and the annual sunshine is 280 ~ 210 h