Phosphoric acid-triggered phosphorus transformation: Structural regulation and long-term phosphorus release mechanism of biochar slow-release phosphate fertilizer.
- 2026-07
- Environmental research 301
- PubMed: 42031052
- DOI: 10.1016/j.envres.2026.124494
Study Design
- Methods
- Co-pyrolysis of waste pomegranate branches with Ca3(PO4)2 and H3PO4 at varying ratios and temperatures, followed by characterization and soil incubation experiments.
- Funding
- Unclear
Addressing the low phosphorus-use efficiency in soils requires sustainable strategies for phosphorus replenishment. Herein, biochar-based slow-release phosphorus fertilizers (BSRPFs) were fabricated through co-pyrolysis of waste pomegranate branches with Ca3(PO4)2, while the addition of H3PO4 was precisely regulated to manipulate internal phosphorus transformation and release behavior. Results demonstrate that phosphate particles were successfully loaded onto the BSRPFs surface. Increasing H3PO4 dosage raised the total phosphorus (25.26-30.20 mg·g-1) and inorganic phosphorus (24.23-28.47 mg·g-1) contents and promoted the conversion of organic phosphorus to inorganic phosphorus during pyrolysis. BSRPFs obtained at higher temperatures exhibited enhanced10 aromatization and structural stability, accompanied by the formation of Ca8H2(PO4)3(OH)) and a dominant HCl-P fraction, which collectively contributed to superior slow-release performance. Phosphorus release was positively correlated with H3PO4 addition and followed kinetics best described by the Pseudo-second-order (R2 > 0.988) and Elovich models (R2 > 0.935). Soil incubation experiments confirmed that BSRPFs could sustainably supply available phosphorus without significantly altering soil pH. Systematic evaluation of H3PO4 addition ratios revealed that a moderate addition (30%) provides an optimal balance, yielding a high total phosphorus content (27.29 mg·g-1) while achieving a desirable slow-release profile (41.04%) and maximizing soil available phosphorus increase. This work highlights a feasible route to convert agricultural waste into efficient slow-release phosphorus fertilizers via H3PO-modulated co-pyrolysis, offering a promising strategy for improving phosphorus utilization in sustainable agriculture.
Research Insights
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