Biocrusts affect preferential flow and water holding capacity by regulating soil properties in Ultisols from subtropical China

Abstract

Biological soil crusts (BSCs) play an important role in regulating the process of soil infiltration, and thus changing soil hydrological processes. However, little attention was paid to the effects of BSCs on soil infiltration and water holding capacity in the humid region. Therefore, the objective of this study was to quantitatively characterize the flow pathways of BSCs on soils developed over Quaternary clay and muddy shale from subtropical China by using dye tracer experiments. To determine the effects of BSCs on soil water holding capacity, the soil water characteristic curve (SWCC) was also measured. Results showed that BSCs significantly reduced the soil water infiltration compared with the bare soil. The dyeing coverage (DC) of BSCs on Quaternary clay and muddy shale decreased by 8.4% and 1.8%, respectively. SWCC results showed that the water content of BSCs was 3.5%–42.8% higher than that of bare soil under the same matrix potential, indicating that BSCs increased the water holding capacity. BSCs affected preferential infiltration by regulating surface soil properties, such as increased soil organic matter content (SOM), silt and clay content, and decreased bulk density (BD) and sand content. Furthermore, PLS-PM results revealed that BSCs and its induced increase of silt and clay content played important roles in inhibiting preferential infiltration. The results could help us to better understand the effects of BSCs on soil hydrological processes in Ultisols from subtropical China.