Abstract:To investigate the effects of extreme soil erosion on physical and chemical properties of soil and crop yield, simulated experiments were conducted in topsoil (30 cm), transition layer (40 cm) and parent material layer (>70 cm) of Mollisols farmlands. Treatments including 70 cm topsoil removal, 30 cm topsoil removal, no eroded soil, 30 cm sediment deposition and 70 cm sediment deposition were set respectively. The results showed that compared with no eroded soil, soil bulk densities, soil mass water contents, soil water storages of the other four treatments were all significantly increased in tillage layer (0—20 cm), while soil porosities, contents of soil water stable aggregates were greater than 0.25 mm, mean weight diameters, geometric mean diameters, field capacities, saturated moistures and soil nutrient contents of the four treatments were all significantly decreased. Furthermore, compared with no eroded soil, corn yields of the treatments of 30 cm and 70 cm soil removal reduced by 42.1% and 52.6%, respectively. There was no significant difference in corn yield between no eroded soil and 30 cm sediment deposition. Corn yield of the treatment of 70 sediment deposition significantly decreased by 12.4%. Thus, extreme soil erosion, no matter topsoil removal or sediment deposition, will lead to the decline of soil quality, reduce soil fertilizer supply and conservation ability , then reduce corn yield.