东北黑土区顺坡垄作和无垄作坡面侵蚀过程对比

目的]以无垄作坡面侵蚀过程为对照,研究顺坡垄作坡面土壤侵蚀过程及机理,为东北黑土区坡耕地土壤侵蚀防治提供科学依据。方法]基于人工模拟降雨试验,设计了3个降雨强度(50,75和100mm/h)以及1个坡度(即顺坡垄作改横坡垄作的临界坡度5°),进行顺坡垄作和无垄作坡面侵蚀过程的对比研究。结果]顺坡垄作坡面径流量和侵蚀量分别较无垄作坡面增加了1.2~1.7和1.3~2.1倍,径流和侵蚀过程也发生了变化。与无垄作坡面相比,顺坡垄沟的集中汇流作用使坡面水流流速增加了1.0~2.3倍,径流剪切力增加了0.7~1.2倍,其坡面侵蚀方式也由片蚀为主转变为以细沟侵蚀为主,细沟侵蚀量可占总侵蚀量的55.3%~65.6%。结论]坡面水流流速增加和细沟侵蚀发生是导致顺坡垄作坡面土壤侵蚀增加的主要原因。

Comparison of Soil Erosion Process Between Longitudinal Ridge Slope and Non-ridge Slope in Mollisol Region of Northeast China

Objective] Longitudinal ridge slope soil erosion process was studied by using non-rige slope as control in order to provide scientific basis for the prevention and control of soil erosion in the northeast mollisol region slope. Methods] Simulated rainfall experiments were conducted. The experimental treatments included two tillage measures (longitudinal ridge and non-ridge tillage), three rainfall intensities (50, 75 and 100 mm/h) and one slope gradient (5°, which was the critical slope gradient for changing longitudinal ridge to contour cultivation). Results] Compared with non-ridge tillage, the total runoff rate and total erosion amount of the longitudinal ridge tillage increased by 1.2~1.7 times and 1.3~2.1 times, respectively. The runoff and sediment process also changed. Compared with non-ridge treatment, the concentrated runoff velocity in furrows of the longitudinal ridge increased by 1.0~2.3 times and shear strength increased by 0.7~1.2 times. Consequently, hillslope erosion pattern shifted from sheet erosion dominant to rill erosion dominant, and rill erosion occupied 55.3%~65.6% of total erosion amount at longitudinal ridge treatments. Conclusion] The increase of runoff velocity and occurrence of rill erosion were two main reasons for the intensification of hillslope erosion at the longitudinal ridge treatment.