Rain infiltration into loess soils from different geographic regions

Loess soils are among the most erodible soils. Therefore, evaluating and enhancing infiltration is paramount in controlling soil loss. A laboratory study was conducted to evaluate the relative difference in infiltration among selected loess surface and subsurface soils from Belgium, Canada, China, and the United States, representing the major loess belts of the Northern Hemisphere. Soils were subjected to simulated rainstorms of constant intensity (I= 41.1mm· h−1), duration (2 hours), and energy rate (27.0 J · m−2 per mm of rain). Infiltration, runoff, and soil water pressure were continuously monitored. Infiltration was described by a linear relationship for the pre-ponding period and by a power series for the post-ponding period. Differences in infiltration response were attributed to differences in soil properties such as differences in organic matter, particle size, swelling clay content, Fe-oxyhydroxides, and carbonates. Despite the high organic carbon content and coarser texture of the Canadian loess surface soil, the presence of highly expansive smectitic clay caused a rapid reduction in infiltration rates indicating the importance of soil mineralogical constituents in surface seal development.