Evaluating the potential of charred bone as P hotspot assisted by phosphate-solubilizing bacteria

The enhanced phosphorus (P) release from charred bone by microorganisms results in hotspots to alleviate P limitation in agricultural and natural systems. This study compared P release, assisted by phosphate-solubilizing bacteria (PSB), from charred bone (CB) produced at various temperatures (100-300 °C). In the absence of PSB, soluble P from CB in water was observed with fluctuation between 100 and 300 °C, with a maximum value of 8.66 mg/L at 200 °C. Similarly, kinetics of dissolution indicated that CB produced at 250 °C owned the highest solubility and dissolution rate. After the addition of PSB, soluble P from all the CB samples were all elevated. The CB produced at 100 °C incredibly showed the most significant enhancement (from 3.51 to 77.37 mg /L). ATR-IR and XPS confirmed the loss of organic matter (primarily collagen), but no significant mineralogical alternation of bioapatite in bone. Meanwhile, it demonstrated that collagen itself cannot provide soluble P. However, the collagen contributed to the substantial sorption of bacteria, which improved the efficiency of P release from CB surface. This study clarified the P release via the interaction between CB and PSB, and hence provided a new perspective on understanding P biogeochemical cycle in ecosystem.