Assessing Silica-Enriched Biochar and N, P, K Fertilization in Newly Flooded Inceptisols: Impacts on Soil Chemical Properties, Phosphorus Use Efficiency, and Rice Productivity

Phosphorus (P) limitation remains a major constraint to rice productivity in newly flooded Inceptisols, despite relatively high total P reserves. The conversion of mineral soils into paddy fields induces rapid changes in redox conditions, iron dynamics, and silica availability, which strongly influence P availability and fertilizer efficiency. In recent years, silica-enriched biochar has emerged as a promising soil amendment due to its capacity to improve soil chemical properties, regulate iron-mediated P fixation, and enhance nutrient retention in flooded soils. This narrative review synthesizes recent advances on the roles of silica-enriched biochar and N, P, K fertilization in modifying soil chemical properties, phosphorus use efficiency, and rice productivity in newly flooded Inceptisols. The review highlights the effects of these management strategies on soil pH, cation exchange capacity, available and potential P pools, silica dynamics, plant P and Si uptake, and yield components such as grain yield and 1000-grain weight. Evidence from recent studies indicates that silica-enriched biochar contributes to improved P availability through competitive sorption with phosphate on iron oxides and increased cation retention, while balanced N, P, K fertilization enhances nutrient uptake and yield performance. Synergistic effects between biochar-silica and mineral fertilization are particularly important during the early stages of soil flooding, when nutrient dynamics are highly unstable. This review underscores the potential of integrating silica-enriched biochar with optimized N, P, K fertilization as a sustainable strategy to improve phosphorus use efficiency and rice productivity in newly established paddy soils.