Development of biofertilisers from calcined bones: production, and physicochemical and ecotoxicological analysis

The lack of use of raw materials other than cattle and the non-standardization of protocols in the production of calcined bone ash encourages biotechnological investigation of this niche of bio-based fertilizers. The aim was to develop and characterize calcined bone ash from different animal sources and heat treatments. Bovine, porcine and ovine femurs received 2h or 4h heat treatments and their ashes (CBA1, CBA2 and CBA3) were compared to commercial calcined bone ash with unknown processing (CCBA-Unk). In the production analysis, CBA1 and CBA3 had higher yields than CBA2 with 2h while only CBA1 maintained the difference to CBA2 with 4h. In physical-chemical analyses, calcined ashes with 4h demonstrated clearer and more homogeneous granular morphology than with 2h and CCBA-Unk and high mineral concentration, reaching twice the presence of phosphorus and calcium compared to CCBA-Unk. In the ecotoxicological analysis with Artemia salina, all tested ashes were non-toxic, with CBA1 and CBA3 with 4h being safer than the other experimental ashes, reaching four times or twice the lethal concentration in 50% of CCBA-Unk respectively. Bovine and ovine calcined bone ashes for a longer period proves to be more promising than porcine ones for generating nutritional products for acidic soils.