摘 要: | <正> The arid and semiarid land in China covers a vast area, about 3.5 million km~2(not coun-ting the Tibet Plateau),where natural resources are very aboundant. In this area, the totalsolar radiation is as high as 140--160 kilocalorie / cm~2. a. There are about 167 million ha ofvarious grasslands, accounting for nearly 60% of the national grassland area. Arable
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