Investigation of Rainfall Infiltration and Redistribution in Bare Land Within the Black Soil Region of Northeast China Under Traditional Ridge Tillage Practices

A prerequisite for the efficient utilization of water and fertilizer in the traditional ridge farming model in the black soil region of Northeast China is the precise elucidation of the small-scale temporal and spatial characteristics of rainfall infiltration and redistribution. However, the existing research findings have yet to fully satisfy this requirement. To investigate soil water infiltration and redistribution at different positions (ridge bed, ridge side, and furrow) before ridge closure in ridge-furrow crops within the black soil regions of Northeast China, indoor simulation experiments and field natural rainfall monitoring were conducted. The indoor test involved rainfall settings of 12, 16, 20, 24, and 30 mm with a rain intensity of 90 mm/h. Field monitoring recorded a natural rainfall intensity of 56 mm/h lasting 22.5 min, with cumulative rainfall reaching 21 mm (randomly measured), to analyze the process of soil water movement post-rainfall. Results indicated that under conventional ridge planting in black soil areas, prior to ridge bed coverage, the infiltration amounts for ridge bed, ridge side, and furrow under 16 mm rainfall conditions equaled the rainfall itself, with ratios close to 1:1:1, showing no significant redistribution of precipitation during infiltration. For rainfall levels of 20 mm, 24 mm, and 30 mm, the ratios of infiltration to rainfall at the ridge bed, ridge side, and furrow positions were 0.92:1.03:1.04, 0.90:1.03:1.06, and 0.89:1.04:1.09, respectively. When rainfall exceeded 20 mm, the infiltration-to-rainfall ratio was approximately 0.9 and 1.04, respectively. Approximately 10% of the rainfall on the ridge platform migrated to the ridge side via splash and runoff, increasing the water volume at the ridge side by about 4%. For rainfall less than 24 mm, the ridge bed, ridge side, and furrow reached a stable state after approximately 50 min of infiltration and redistribution. For rainfall between 24 mm and 30 mm, the ridge platform stabilized within 50 min, whereas the ridge side and furrow required longer stabilization times. These findings elucidate the spatial variation laws of small-scale rainfall infiltration, providing insights for enhancing soil water and fertilizer utilization efficiency.