Simulated Experimental Effect of Bulk Density on Infiltration Rate of China’s Loess Plateau

Understanding the relationship between bulk density (BD) and infiltration rate is crucial for effective water resource management and land use planning in regions with fragile ecosystems such as the Loess Plateau. The study involved selecting five sampling sites, Yangling (YA), Chunhua (CH), Fuxian (FU), Suide (SU), and Shenmu (SH), covering various climate zones and soil types. Laboratory experiments were conducted to simulate different BD values of 1.00, 1.10, 1.20, 1.30, and 1.40 g.cm-3 were simulated and three replicates were conducted for each soil at each BD level using soil cylinders and a mini disc infiltrometer (MDI) used to measure infiltration rates under various suction heads over time. Particle size distribution, and soil organic carbon (SOC) content were analyzed for each soil. Results showed infiltration rates decreased with increasing suction head and BD value for all soils. Significant correlations were observed between infiltration parameters and soil constituents (Sand, Silt, and Clay). Also, soil parameters of van Genuchten’s model (n, and α) and hydraulic conductivity K, derived from measured data using MDI, varied inversely with BD, high the coefficient of determination (R2) between the data estimated using MDI and those predicted by the Philip model ranged from (R2 > 0.832 - 0.969) in most samples, which demonstrated the quality of the data estimated from MDI device, This study demonstrated that increasing BD reduces soil infiltration capacity due to changes in pore structure. The findings provide insights into managing soil and water resources in the ecologically fragile Loess Plateau region by understanding the impacts of compaction on hydrodynamic processes.