贵州坡耕地水土保持措施效益研究

对旱坡地水土保持的截流沟措施、横坡种植措施和植物篱措施进行效益研究,结果表明:在裸露耕地上,水土流失十分严重,地表径流达到4 044.4m³/hm²·a、土壤流失高达172.4t/hm²·a,以此速率流失土壤,其耕层(15cm)约在12年后,将被冲刷殆尽。截流沟措施与横坡种植措施相比,可减少地表径流702.6m³ /hm²·a和土壤流失19.2t/hm²·a;但其占地面积大,农作物产量低,收益小。植物篱种植措施与横坡种植相比可减少地表径流345.3m³/hm²·a;土壤流失21.0t/hm²·a。虽然植物篱占据耕地面积,但并不影响农作物产量。植物篱种植下的耕层土壤的酸碱度和质地得到改善,土壤养分含量有所提高,土壤侵蚀速率远低于易风化土壤的成土速率,同时结合人工翻耕,每年平均以17.5cm的速度形成梯坎,以1.1°的速度减缓坡度。该项措施最终可实现坡改梯的目的,实现旱坡地的可持续利用。

A Study on Effects of Soil and Water Conservation Measurements on Sloping Land in Guizhou

After eight-year study on effects of soil and water conservation measurements which were alley cropping,cross channel and cross planting on sloping land in Guizhou,the results showed soil erosion on the bared sloping farmland was very serious.The runoff reached 4044.4 m³/ha·a and the soil loss reached 172.4t/ha·a on it.The topsoil (15cm) will be eroded and the productivity of soil will be lost after 12 years in case of such erosion.Cross channel measurement on sloping land could reduce runoff by 702.6m³/ha·a and soil loss by 19.2t/ha·a compared with cross planting measurement,but the crop yield and income were low since the cross channel occupied much more area of land.Alley cropping measurement could reduce runoff by 345.3 m³/ha·a and soil loss by 21.0t/ha·a in comparison with cross planting measurement.Although parts of land were occupied by alley crops,the crop yield did not reduce.Soil pH,soil texture and nutrition contained in top soil were enhanced and the soil erosion rate was further lower than soil weathering rate under alley cropping measurement.Combined with land cultivation, the sloping land could be terraced at a speed of 17.5cm per year and slow down the sloping at a speed of 1.1°.The sloping land to be terraced and to be cultivated sustainably can be achieved under the alley cropping measurement finally.