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山东沂蒙山区南部的临郯蒼大平原,是魯南山区最肥沃的地方,有沂沭河纵貫南北,地势低洼,多为湖洼地。除沂沭河两岸的河沙土、河淤土和黄土外,其余大部分为黑土和老土(即为沼泽草甸土),两者共計366多万亩,其中老土为250多万亩。一、老土的分布規律老土主要分布在平原稍低,而比湖洼地又稍高的地方(图1),是黑土經过多年耕作熟化而成的。因老
Shandong Yimeng mountain southern Linqu Cang plain, is the most fertile place in the mountains of Lunan, Yishu River runs north and south, low-lying, mostly lake depressions. Except for river sand, river silt and loess on both banks of Yishu River, most of the rest are black soil and old soil (that is, swamp meadow soil), both of which total more than 3.66 million mu, of which more than 2.5 million mu are old soil. First, the law of the old soil distribution Old soil is mainly distributed in the lower plain, and slightly higher than the lake depressions (Figure 1), is the black soil after years of farming and aging. Because of the old