Tham khảo tài liệu 'herbicides environmental impact studies and management approaches part 10', khoa học tự nhiên, công nghệ sinh học phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Velvet Bean Mucuna pruriens var. utilis a Cover Crop as Bioherbicide to Preserve the Environmental Services of Soil 169 considered in a broadest sense and not only as a rudimentary way to add nitrogen to the soil. This comprehensive concept has been adopted in this work to use velvetbean as bioherbicide. 3. Historical use of cover crops and green manures Interest to preserve soil fertility for crop production through the use of legumes as cover crops or green manures has been known since the origin of agriculture Allison 1973 Tivy 1990 Sarrantonio 1991 Winiwarter 2006 Williams 2006 . In China and Japan the use of cover crops and green manures -mainly legumes- that were incorporated directly to the soil as soil improvers or used as rotation associated or relay crops to support cereal crops has been documented since over 3000 years ago. It was also a common practice in Greece Rome and Mesoamerica under conditions of cheap labour water restrictions and lack of inorganic fertilizers Allison 1973 Hauck 1977 Winiwarter 2006 Williams 2006 . By 1976 the surface area cultivated with green manures in China was nearly million hectares Hauck 1977 . Such soil conservation and management practices developed by ancient agricultural civilizations were adopted and remained virtually unchanged in most of the agricultural regions of the world until 1840 when the practice of soil fertilization with guano and superphosphates began. However widespread use of those materials did not start until 1900. In Germany the chemical fertilizers industry began in 1850 incentivized by Julius von Liebig s work on fertility and plant nutrition. Overall it was not until 1945 when the intensive use of synthetic fertilizers in agriculture and livestock raising began in the USA Europe and Australia Allison 1973 Tivy 1990 Mulvaney et al. 2009 . Traditional agriculture in the USA Europe Australia and Mesoamerica consisted of prairie rotation with a wide variety of cereal root and legume crops which .
