Insights into the Maturity of Keratin Byproduct-Based Biofertilizer by UV-Vis, Fourier Transform Infrared...

Dog hair keratin byproducts are extremely resistant to degradation and require appropriate waste management technologies. To enhance the degradability of these byproducts, silo cocomposting with food byproducts was performed for 19 weeks. In this study, the physical-chemical analysis (temperature, pH, electrical conductivity, carbon/nitrogen ratios (C/N), germination index, and mineral nutrients) was combined with spectroscopic technologies (ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM)) as an advanced tool to effectively monitor the maturity of compost, thereby minimizing excessive consumption of time and products. Furthermore, a partial least-squares regression (PLS-R) model was used to predict the final compost quality. As a result, it can be concluded that the compost produced fulfills the norms of applicability of mature compost in agriculture with a C/N ratio below 20 and a germination index of 100%. These results were confirmed by UV-spectroscopy analysis showing an increase in humification and by FTIR depicting the degradation of disulfide bonds in cysteine present in keratin and the degradation of cellulose, hemicellulose, and lignin in food byproducts. This study confirms that a well-managed degradation of keratin byproducts enables them to be upgraded into a valuable product that could be used to improve the fertility of degraded soils and promote plant growth.