不同地表条件下黑土区坡耕地侵蚀过程中土壤团聚体迁移

Soil Aggregate Transport During Soil Erosion Process Under Different Soil Surface Conditions on Black Soil Slope Farmland

土壤侵蚀过程中,土壤团聚体的迁移反映了团聚体的破碎程度及径流的搬运能力,直接影响着侵蚀强度。以东北典型薄层黑土区耕层土壤为研究对象,采用模拟降雨试验方法,研究裸露休闲、纱网覆盖与秸秆覆盖3种地表条件下不同粒级(>5mm,2～5mm,1～2mm,0.5～1mm,0.25～0.5mm和<0.25mm)土壤团聚体的迁移特征。结果表明:(1)纱网覆盖与秸秆覆盖具有削减径流和抑制侵蚀的作用,其中抑制产沙作用更明显,减沙率分别为75%和99%以上;(2)3种地表条件下,<0.25mm团聚体是主要的流失粒级,其占到团聚体流失总量的50%以上;各粒级流失量均表现为:裸露休闲>纱网覆盖>秸秆覆盖;(3)纱网覆盖和秸秆覆盖下的团聚体粒级分布与裸露休闲的相比,差异较为明显的均是<0.25mm粒级,该粒级流失量较裸露休闲的分别减少74.62%和99%;秸秆覆盖与纱网覆盖之间差异明显的是<0.25mm与1～5mm粒级,流失量较纱网覆盖的分别减少97.81%和86.03%;(4)秸秆覆盖下团聚体平均重量直径表现为最大;分形维数和平均重量比表面积均表现为:裸露休闲>纱网覆盖>秸秆覆盖。

During soil erosion process, soil aggregate transport reflects the broken degree of soil aggregate and runoff transport capacity, which directly affects soil erosion degree. A laboratory rainfall simulator study was conducted to determine characteristics of sediment yield and soil aggregate transport of different size fractions （〉5 mm, 2-5 ram, 1-2 mm, 0.5-1 ram, 0.25-0.5 mm and d0.25 ram） under different soil surface conditions on typical black soil in the northeast China. Three soil surface conditions were designed. The bare land, nylon net cover and straw cover. Results showed that： （1）Nylon net cover and straw cover not only decreased runoff but also sediment yield, while sediment yield reduction was above 75% and 99%, compared with the bare land, respectively;（2）〈0.25 mm soil aggregate was the main lost soil aggregate size fraction for all the treatments, occupying by above 50- of the total sediment yield- the loss of each soil ag- gregate size fraction ranked in order of the bare land-nylon net cover 〉 straw cover〉（3）The most pro- nounced difference of soil aggregate transport was d0.25 mm between the bare land and nylon net cover or straw cover, the size fraction loss from nylon net cover and straw cover reduced by 74.62- and 99%, com- pared with the bare land, respectively- there was a large difference of 〈0.25 mm and 1-5 mm transport be- tween straw cover and nylon net cover, while loss of these soil aggregate from straw cover decreased by 97.81% and 86.03%, relative to that from nylon net cover, respectively- （4）The mean weight diameter of soil aggregate from straw cover treatment showed the greatest value, while fractional dimension and mean weight soil specific area were both in order：The bare land〉nylon net cover〉straw cover.