喀斯特区两种岩性发育土壤入渗特征及其影响因素

为探究土壤理化性质和植物根系结构对喀斯特区白云岩和砂页岩发育土壤入渗特征的影响，本文以环江县典型喀斯特峰丛洼地小流域为研究对象，采用圆盘入渗仪（DJ-WS）进行4个压力水头（0、-3、-6和-9 cm）的土壤入渗实验，同时利用数字扫描仪测定根系结构指标，分析两种岩性不同土地利用发育的土壤入渗性能的差异以及影响土壤入渗的主控因素。结果表明：1）土壤稳定入渗率均随着压力水头的增大而增大，且白云岩大孔隙导水能力均强于砂页岩；2）砂页岩土壤根系结构指标均明显高于白云岩；3）白云岩土壤导水率均与有机质含量、总孔隙度、根系根长密度和根系体积密度呈现显著或极显著正相关；砂页岩土壤导水率均与有机质含量和总孔隙度呈现显著或极显著正相关，与大孔隙导水能力和根系结构指标存在显著正相关，与容重呈现显著负相关；逐步回归表明，白云岩发育土壤入渗受控于根系根长密度和根系体积密度，砂页岩发育土壤入渗受控于根系体积密度。综上，根系根长密度和根系体积密度是影响喀斯特区白云岩和砂页岩发育土壤入渗的主控因素。研究结果以期为深入认识喀斯特区水分入渗以及地下漏失提供新的研究思路与科学理论支撑。

Infiltration characteristics and influencing factors of two types of lithological soils in karst regions

This study aims to investigate the impact of soil physicochemical properties and plant root structure on the soil infiltration characteristics of dolomite and sand shale developed soils within karst areas. Focused on the typical karst peaks and depressions sub-watersheds in Huanjiang County, soil infiltration experiments were conducted using a disc infiltrometer (DJ-WS) at four pressure heads (0, -3, -6, and -9 cm). Simultaneously, a digital scanner was employed to determine root structure indexes, aiming to analyze the disparities in soil infiltration performance developed by these lithologies under different land uses and to identify the primary controlling factors influencing soil infiltration. The results revealed the following: 1) The stable soil infiltration rate consistently increased with the elevation of pressure head, wherein dolomite showcased superior water-conducting capacity within its larger pore spaces as compared to sand shale; 2) The root structure indicators in sand shale soil significantly surpassed those observed in dolomite; 3) The water-conducting rate of dolomite soil displayed significant or highly significant positive correlations with organic matter content, total porosity, root length density, and root bulk density. The water conductivity of sand shale soil exhibited noteworthy or highly noteworthy positive correlations with organic matter content and total porosity. Moreover, it displayed significant positive correlations with macroporous hydraulic conductivity and root structure indexes, while indicating a notable negative correlation with bulk density. Through stepwise regression analysis, it was elucidated that the infiltration of dolomite-developed soil was predominantly regulated by root length density and root bulk density. In contrast, the infiltration of sand shale-developed soil was primarily controlled by root bulk density. Consequently, root length density and root bulk density emerged as the principal controlling factors influencing soil infiltration in both dolomite and sand shale developed soils within karst areas. These results aim to offer novel insights for a more profound comprehension of water infiltration and subsurface seepage in karst regions, thereby laying a robust foundation for scientific theories and further investigations.