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农业的发展是人类文明的必要前提。当人们开始种植作物时就意识到,如果清除与作物竞争的非栽培植物时,就能获得高产。但是人类对农业创造性的活动以后,杂草的种群、密度、覆盖度不是减弱了,相反地却加重了杂草问题的严重性。例如从其它国家引种植物时,往往把引进的植物变成严重的杂草,或者夹带其他杂草种子而引起蔓延。据美国农业部1895年年鉴中列出的在美国发生的200种杂草中,有108种来源于国外。随着农业技术从利用自然
The development of agriculture is a necessary prerequisite for human civilization. When people start planting crops, they realize that they can achieve high yields if they remove uncultivated plants that compete with their crops. However, after the human activities of agriculture, the population, density and coverage of weeds are not weakened, but on the contrary aggravate the seriousness of weed problems. For example, the introduction of plants from other countries, the introduction of plants often become serious weeds, or entrain other weed seeds caused by the spread. Of the 200 weed species in the United States listed in the 1895 Almanac of the United States Department of Agriculture, 108 are from abroad. With the use of agricultural technology from nature