Synergistic Biofirefighting: Closed-Loop Nutrient-Recycling Hydrogel for Forest Fire Extinguishment and Postfire Agroecosystem Regeneration.

Global wildfires have grown increasingly severe. Conventional fire suppressants exhibit low fire-extinguishing efficiency, re-ignition risks, environmental contamination, and cumbersome preparation procedures. Herein, a biofertilizer-based hydrogel (BBH) was fabricated using food additives and compound fertilizers as all-biomass raw materials. The resultant material is low-cost and suitable for large-scale production. Different from traditional single-functional hydrogels, this material operates via a gas-liquid-solid three-phase coupled flame-retardant mechanism based on bound water cooling, phosphorus radical quenching, and the formation of carbon "aerogel-like" barriers. BBH achieves a high limiting oxygen index (LOI) of 84.2%, and its flame-retardant efficacy delivers a 3.3-fold improvement compared with commercial counterparts. Compared with pure water, this hydrogel shortens the fire-extinguishing time by 60% and reduces material consumption by nearly 70%, and no re-ignition is observed throughout all tests. Furthermore, BBH supports an integrated closed-loop system combining fire suppression and in situ ecological restoration. After BBH effectively extinguishes wildland fires, appropriate residues remaining in soil and on plant surfaces impose no environmental burden; its biodegradable residues can release nitrogen, phosphorus, and potassium, which effectively promote plant growth. This work provides a theoretical foundation and feasible technical route for the development of high-efficiency and eco-friendly wildfire suppression materials.