Abstract:Red mud was used as a compost carrier to prepare a geological fertilizer that was used to improve rocky desertification soil. The composition of particles, bulk density, aggregates and nutrient indexes of the soil transverse interface and radial profile was then tested and analyzed under simulation of varying rainfall erosion and infiltration conditions. Further, a three-dimensional evaluation and analysis of the improvement caused by the geological fertilizer was conducted. The results show that the red mud-based fertilizer enhances the resistance to rainfall erosion and infiltration of the transverse and radial interfaces of the rocky desertification soil. Under rainfall intensities of 15–90 mm/h, the transverse loss of soil could be maintained in the range of 19.49%–72.20%. In addition, the clay content of the soil drops by less than 20%, whereas organic matter (OM), total nitrogen (TN), total phosphorus (TP), and other nutrient indexes drops to a minimum of 3.89%. The bulk density of the 0–20 cm top soil decreases progressively from 1.18 g/cm3 to 0.86 g/cm3, while the water-stable aggregate volume rises from 45.33% to 75.57%. Under infiltration conditions that vary from 1 000 mm to 3 000 mm, the infiltration rates of OM, TN, available phosphorus, available potassium, and other nutrient indexes in each layer of the radial soil profile decrease significantly. Overall, the lowest attrition rate is 2.86%. Data from infrared analysis shows that intensities of absorption peaks that are characteristic of nutrients in the geological fertilizer are significantly enhanced. The porous structure associated with particles of the red mud-based geological fertilizer promotes the retention and adhesion of nutrients in the soil matrix. Considering the trends of losses associated with physical and chemical indexes and effects of the soil structure, improvement effect of 15% red mud base mass fertilizer on rocky desertification soil is the best.