一、机械化保护性耕作技术的起源保护性耕作起源于美国20世纪30年代席卷美国大地的“黑风暴”,特别是1935年5月,狂风把田野中的沃土卷起,天空一片昏暗,已见不到太阳,连续三天,从西部刮到东部,横扫了2/3的美国国土,把3亿多吨土壤送入大西洋。大风过后,田野荒芜,土地绝产。经过多 I. The Origin of Mechanized Conservation Tillage Conservation tillage originated in the “Black Storm” that swept through the United States in the 1930s in the United States. In particular, in May 1935, the wind rolled up the fertile ground in the fields and the sky was dim. To the sun, for three consecutive days, swept from the west to the east, sweeping two-thirds of the U.S. territory and sending more than 300 million tons of soils to the Atlantic Ocean. After the wind, the fields were deserted and the land was in abeyance. After more