Comparing of soil matrix infiltration and preferential flow across different land use types in karst landscapes: Implications for soil and water conservation

Soil infiltration is crucial for regulating water storage, distribution, and movement in karst landscapes with diverse land use types. However, lack quantitative research resulted in unclear mechanisms of matrix infiltration and preferential flow across different land use types. This study examined five land use types—secondary forest land (SFL), abandoned land (AL), woodland (WL), orchard land (OL), and cultivated land (CL) in hillslope and depression. Soil matrix infiltration and total infiltration were measured using a surface-positioned double-ring infiltrometer, while preferential flow was quantified by subtraction. The soil infiltration process model applicability exhibited land-use dependency, which also reflected the variations in their infiltration mechanisms. Cumulative total infiltration (CTI, 380–3152 mm) and preferential flow (PFCI, 176–2755 mm) both followed: WL > OL > AL > SFL > CL, with PFCI contributing 42.8 % to 82.4 % of CTI. Cumulative matrix infiltration (CMI, 169–268 mm) followed: CL > WL > SFL > OL > AL, with CL showing the highest CMI contribution to CTI at 57.2 %, compared to 23.8 %, 22.0 %, 21.3 %, and 17.6 % for SFL, OL, WL, and AL, respectively. Total porosity was the primary factor promoting both matrix infiltration and preferential flow. Increasing silt and decreasing clay promoted matrix infiltration and inhibited preferential flow, enhancing soil water storage. Tillage impacted infiltration more than soil properties, resulting in CL exhibiting the highest matrix infiltration and the lowest preferential flow. To enhance soil and water conservation in karst landscape, we recommend allocating CL and OL to depressions and SFL and WL to hillslopes. This study deepens understanding of soil infiltration and provides a scientific foundation for sustainable management of karst landscapes.