Restoring soil quality and root morphology of peanut under simulated topsoil erosion: effects of fertilization strategies in a controlled study

Soil erosion and deposition are critical processes affecting soil quality and crop productivity, particularly in hilly agricultural regions. Topsoil removal reduces soil fertility and degrades root development, threatening sustainable crop production. This study aimed to evaluate how different degrees of topsoil erosion and deposition, combined with different fertilization strategies,influence soil quality and peanut (Arachis hypogaea L.) root morphology. We sought to determine effective fertilization measures for restoring soil functionality and improving root growth under erosion stress. A controlled pot experiment simulated five topsoil redistribution scenarios: moderate (10 cm) and severe (20 cm) erosion and deposition, and a no-change control. Each scenario was combined with four fertilization treatments: no fertilizer, inorganic fertilizer, organic fertilizer, and combined organic-inorganic fertilizer. Soil chemical properties, soil quality index (SQI), and peanut root morphology were assessed. Topsoil erosion reduced soil organic matter, nitrogen, and phosphorus contents, with 20 cm erosion decreasing root diameter at flowering by 21.8% under inorganic fertilization and 19.3% under combined fertilization compared with the control. Erosion consistently resulted in reduced plant height, root diameter, root length, root surface area, and root volume. In contrast, deposition improved soil nutrient availability, enhancing root growth. Root length increased by 75.5% and root surface area by up to 116.7% under 20 cm deposition with combined fertilization, relative to the control. Fertilization mitigated erosion effects, with the combined organic-inorganic treatment achieving the highest SQI and best root performance. The maximum SQI value (0.417) was observed under 20 cm deposition, and combined fertilization consistently outperformed inorganic or organic fertilization alone. Organic fertilizer alone maintained more stable root morphology under erosion conditions. Topsoil redistribution profoundly alters soil quality and root morphology in peanut production. Appropriate fertilization, particularly combined organic-inorganic application, is essential for restoring soil functionality and sustaining crop productivity in erosion-affected areas.