Background In the arid regions of northern China, the natural environment is characterized by poor conditions and significant ecological damage, resulting in a prevalence of land desertification and soil erosion. These conditions impede sustainable economic and social development. The combination of red clay and aeolian sandy enhances the soil’s water absorption and retention properties, thereby reducing water loss from the aeolian sandy. However, there is a paucity of research addressing the soil improvement effects of red clay and aeolian sandy, especially in the Kubuqi Desert. In order to investigate the hydrological effect of red clay compounding aeolian sandy soil, providing a theoretical foundation for advancing the management of aeolian sandy soil.

Methods In this study, red clay and aeolian sandy soil were mixed in accordance with a series of mass ratios, including 0∶1(completely aeolian sandy soil), 1∶4, 2∶3, 3∶3, 4∶1, and 1∶0 (completely red clay). The infiltration rate of the soil was then determined through the utilization of the ring knife method, and the effects of integrating red clay with aeolian sandy soil on the water infiltration process were subsequently analyzed. This investigation involved a thorough examination of how the combination of these two soil types influences water infiltration dynamics. In addition, a detailed simulation of the infiltration process was performed.

Results The content of clay in the compound soil increased significantly when the red clay added, ranging from 18.57 to 123.43 times the original value. Additionally, the range of particle size distribution expanded, enhancing the homogeneity of soil particle size and resulting in a finer soil texture. The saturated water holding rate, capillary water holding rate, water holding rate in the field increased gradually with the addition of red clay, and the capillary porosity of the compound soil was 1.10 to 1.21 times than that of the aeolian sandy soil, which enhanced water retention capabilities. As the proportion of red clay within the composite increased, both the initial infiltration rate and the average infiltration rate exhibited a gradual decline, the duration for soil to reach stable infiltration was extended. The infiltration capacity of the composite soil with a 1∶4 ratio was diminished significantly, leading to a substantial reduction in the movement of water into deeper soil layers. Water infiltration characteristics of red clay and aeolian sandy combining were more accurately represented by the Horton model (R² > 0.93).

Conclusions In summary, a mixture of red clay and aeolian sandy soil in a 1∶4 ratio proves highly effective for soil improvement.