风蚀严重地威胁着降水量低而多变的任何地区,那里干旱频繁,温度高,蒸发量和风速都大.美国大约7千万(?)土地,其中包括5.5万(?)作物耕地、9百万(?)草原地以及6百万(?)其它用地这是至关紧要的问题.良好的耕作措施,如作物轮作、控制放牧,能够保护这些土地34%左右;但是4.6千万(?)土地的特殊风蚀需要防止,每年大约有4.8百万(?)遭受中等程度的损害. Wind erosion is a serious threat to any area where precipitation is low and variable, with frequent droughts, high temperatures, large amounts of evaporation and winds.About 70 million U.S. land, including 55,000 cropland, 9 This is a crucial issue for millions of grassland and 6 million other sites. Good farming practices, such as crop rotation and grazing, can protect about 34% of these lands; but 4.6 million (? Special wind erosion on the land needs to be prevented, with about 4.8 million (?) Suffering moderate damage each year.