黄土高原风蚀水蚀交错区农田生物结皮对土壤渗透性的影响

Effects of biological soil crusts on soil permeability of croplands in wind-water erosion crisscross region of Loess Plateau

为了明确黄土高原风蚀水蚀交错区农田生物结皮的分布状况及其对土壤渗透性的影响,本文以该区农田(春玉米)土壤自然发育的生物结皮为对象,通过野外调查,探索了该区农田生物结皮盖度及组成。并在此基础上,以裸土为对照,采用环刀法和双环法测定了土壤水分入渗参数,研究了农田藻结皮及藓结皮对土壤渗透性的影响。结果表明:风蚀水蚀交错区水浇地和旱地中均有生物结皮分布,平均盖度为42.11%,其中藻结皮盖度为33.74%,藓结皮盖度为8.37%。生物结皮显著降低了农田土壤饱和导水率,与裸土相比,藓结皮和藻结皮覆盖下土壤0~5 cm土层土壤饱和导水率分别降低55.14%和23.54%;藓结皮使土壤的稳定入渗速率、平均入渗速率及累积入渗量分别显著降低了51.11%、47.71%和46.50%,藻结皮使土壤的稳定入渗速率、平均入渗速率及累积入渗量分别降低了25.56%、21.10%和20.91%,但与裸土差异不显著。藓结皮的形成能够降低农田土壤砂粒含量,提高土壤黏粒含量,进而降低农田土壤渗透性。综上,生物结皮的形成导致了农田土壤渗透性的降低,这可能会进一步影响农作物对土壤水分的有效利用。

To determine the distribution of biological soil crusts(biocrusts)and their influence on soil permeability in croplands in the wind-water erosion crisscross region of Loess Plateau,the natural biocrusts in the croplands(corn)soil were investigated.First,the coverage and composition of biocrusts in croplands soil in this region were investigated.Subsequently,soil water infiltration parameters were measured using ring knife and double ring methods,respectively,and lastly,the influence of cyanobacteria and moss crusts on soil permeability was studied.The results showed that biocrusts are widely distributed in both irrigated and dry croplands in wind-water erosion crisscross region,and the average coverage is approximately 42.11%,of which cyanobacteria and moss crusts respectively account for 33.74%and 8.37%.Biocrust significantly decreased the saturated hydraulic conductivity of croplands soil compared with that of bare soil.Compared with bare soil,the saturated hydraulic conductivity of 0-5 cm soil layer covered with moss and cyanobacteria crusts decreased by 55.14%,and 23.54%,respectively.Compared with bare soil,moss crusts significantly reduced the stable infiltration rate,initial infiltration rate,and cumulative infiltration amount of soil by 51.11%,47.71%,and 46.50%,respectively.Cyanobacteria crusts reduced the stable infiltration rate,initial infiltration rate,and cumulative infiltration amount by 25.56%,21.10%,and 20.91%,respectively,which did not vary significantly from those of the bare soil.The formation of moss crust in cropland can reduce soil sand content,increase soil clay content,and consequently reduce croplands soil permeability.In conclusion,the formation of biocrusts in cropland has resulted in the decrease of croplands soil permeability,which may affect the effective utilization of soil water by crops.