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Purdue大学的Anson Bertrand和J er r yMannering1963年曾指出:“今天的趋势是朝向最少耕作,但不可丢掉中耕机。” 近20多年来,化学除草剂的发展有了很大进步不需中耕控制杂草已成为可能,而且农家也常常劝告:如果土中无杂草,就没有理由进行中耕。然而我们的调查却表明,对大多数中耕作物,农家是要进行中耕的(表1)。其理由何在? 表1 美国1984年主要中耕作 物的平均中耕次数 (美国农业部经济研究所)
Anson Bertrand and Järä Mannering of Purdue University pointed out in 1963: “The trend today is toward least cultivation, but we must not discard cultivators.” The development of chemical herbicides has greatly improved in the past 20 years. Grass has become possible, and farmers often advise: There is no reason to cultivate if there are no weeds in the soil. However, our survey shows that for most cultivated crops, the farmhouse is for cultivating (Table 1). The reasons for this are as follows: Table 1 Average Drought Times of Major Upland Crops in the United States in 1984 (USDA Institute of Economic Research)