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坡耕地的水土流失不仅是造成河流、水库淤积的一个重要原因,更严重的是每年丧失大量肥沃表土,导致土壤退化和农业减产。其危害已成为全世界共同关注的问题。据联合国环境规划署估计,由于土壤侵蚀,全世界每年丧失可耕地500—700万公顷,到本世纪末还可能上升到1,0005万公顷。防治水土流失,保护每一寸土地,已是刻不容缓的任务,也是世界性国土整治的共同目标。美国、苏联等一些国家对坡耕地的水土流失问题很重视,有关保持水土的耕作措施,诸如等高耕种、草田轮作、地面覆盖、免耕法等,都进行了大量的试验研究和推广
Soil erosion in sloping arable land is not only an important cause of siltation of rivers and reservoirs, but more serious is the loss of large amounts of fertile topsoil each year, which leads to soil degradation and agricultural yield reduction. Its harm has become a common concern in the world. The United Nations Environment Program estimates that the world loses about 5 to 7 million hectares of arable land each year due to soil erosion and may rise to 10,105 hectares by the turn of the century. Preventing soil and water loss and protecting every inch of land is an urgent task and a common goal of world-wide land remediation. Some countries, such as the United States and the Soviet Union, attach great importance to the problem of soil and water loss on sloping arable land. A great deal of experimental research and promotion have been carried out on tillage measures to maintain soil and water, such as contour cultivation, crop rotation, ground cover and no-tillage methods