Changes in the Bio-Availability of Phosphorus in Pyrochars and Hydrochars Derived from Sewage Sludge after Their Amendment to Soils

The expected shortage of global phosphate has enforced the search for alternative resources P fertilizers. Therefore, present study focuses on turnover phosphorus (P) hydrochars and pyrochars derived from sewage sludge (SS) in soils during plant growth. We designed a pot experiment which Lolium perenne L. was allowed to grow Calcic Cambisol amended with SS-derived chars. Hydrothermal carbonization (HTC) yielded SS-hydrochars (200 °C, 260 °C; 30 min, 3 h), whereas SS-pyrochars were obtained after dry pyrolysis (600 1 h). Increasing severity HTC lowered recovery total (PT) feedstock 76%. Olsen-P diminished 4% PT untreated 1% hydrochars, exhibited an between 6%. At end experiment, produced at 200 °C contained more than unamended soils, proving that P-rich chars can indeed serve as fertilizer. Part sequestered turned into mobile form experiment. After addition our chars, soil pH remained alkaline, allowing conclusion could not have been solubilized through just abiotic processes. suggest biological biochemical processes are involved this mobilization. This work demonstrates that, order evaluate efficiency organic amendment fertilizer, knowledge their availability alone is sufficient better understanding cycling its immobilized certainly required.