Using a tiny rainfall simulator to investigate the impact of soil internal forces on long-term location fertilization Loess soil loss

Soil water erosion and the resulting nutrient loss (such as phosphorus loss) and other ecological and environmental issues are still important obstacles that challenge the quality and efficiency of agricultural production and sustainable development in the Loess Plateau of China. Soil water erosion is affected by external environmental factors such as rainfall intensity and slope. Measures such as increasing vegetation coverage and reducing slope can play an external role in preventing and controlling soil and nutrient loss. At present, based on the Universal Soil Loss Equation (USLE) and the Revised Universal Soil Loss Equation (RUSLE), Chinese scholars have established regional soil loss models such as the erosion prediction model for small watersheds in loess hilly and gully regions, which play a very important role in soil erosion prediction and prevention. However, all the above models are empirical and lack consideration of the mechanism of soil erosion. In this study, using a self-designed needle drop micro-rainfall model device combined with the basic principles of soil electrochemistry, the effect of the interaction between soil particles on the loss of soil and its nutrients during long-term fertilization was studied on a mesoscopic scale. We found that: (1) the total phosphorus content of loess soil under long-term phosphate fertilizer treatment was 2.46 times that of non-phosphorus treatment, but its surface potential, surface charge density, surface electric field intensity, specific surface area, and number of surface charges were all lower than those of non-phosphorus treatment; (2) loess soils with varying levels of phosphorus exhibit a trend in which the loss of soil particles and phosphorus increases as the surface potential of the soil particles, and there is a linear positive correlation between the cumulative loss of particulate phosphorus and the cumulative loss of soil particles; (3) the net force (the combined force of van der Waals force, hydration repulsion force, and electrostatic repulsion force) between soil particles with different phosphorus levels at a given electrolyte concentration is all expressed as repulsive force and changes with the decrease of electrolyte concentration; (4) due to the relatively high surface potential of low-phosphorus loess soil, the electrostatic repulsion between soil particles is greater, resulting in poor stability of soil aggregates and more cumulative loss of soil particles and attached phosphorus. This study clarified the relationship between soil surface properties, soil internal forces, soil particles and nutrient element loss characteristics under long-term fertilization treatment, and provided new ideas for soil loss prevention and control and environmental risk assessment during long-term fertilization.