大渡河干旱河谷区不同土地利用方式下土壤抗冲性特征

Soil anti-scourability under different land use types in arid valley area of Dadu River

为弄清干旱河谷地带土壤抗冲性的变化特征,采用野外调查与原状土冲刷相结合的方法,开展干旱河谷区不同土地利用方式下土壤抗冲性变化特征研究。结果表明:1)在土壤冲刷过程中,3种土地利用方式径流含沙量总体呈先减少后趋于平稳的变化趋势;土壤抗冲性符合随冲刷时间的延长而增强的规律。2)土壤抗冲性与团聚体平均重量直径(MWD)和几何平均直径(GMD)呈极显著正相关,与>0.25mm团聚体含量(WR0.25)和土壤非毛管孔隙度呈显著正相关,与土壤容重呈显著负相关;土壤抗冲性与根长密度、根表面积密度和根体积密度呈极显著正相关,与根重密度呈显著正相关。3)草地抗冲性能最好,经果林次之,农耕地最差。研究表明改善土壤结构、提高土壤团聚体稳定性及增加根系密度对强化土壤抗冲性起到重要作用,研究区可通过土地利用方式调整,以期为干旱河谷地带水土流失有效防控提供科学依据。

In order to clarify the factors influencing the soil anti-scourability under different land use types in the dry valley,a combination of field investigation and soil scouring was used to study variation characteristics of soil anti-scourability in fruit forests,farmland and grassland.1)During the soil scour process,the runoff sediment content in different land uses generally shows a trend of firstly decreasing and then stabilizing,soil anti-scourability increases with the extension of scour time.2)Soil anti-scourability is significantly positively correlated with aggregate mean weight diameter and geometric mean diameter,positively correlated with0.25mm aggregates content and soil non-capillary porosity,and negatively correlated with soil bulk density.There is a very significantly positive correlation between root length density,root surface area density and root volume density,and a positive correlation with root weight density.3)Grassland has the best anti-scourability performance,followed by fruit forest,and farmland is the worst.It shows that improving soil structure,increasing soil aggregate stability and root density play important roles in enhancing soil anti-scourability.The research results provide a scientific basis for the effective prevention and control of regional soil erosion.