Evaluation of change in biochar properties derived from Eragrostis tef straw and pyrolysis temperature for agricultural application

In this study, the potential use of Eragrostis tef straw (ETS) was investigated, which is one of the most prevalent agro-wastes in Ethiopia and East Africa. It is typically discarded and contributes to environmental pollution. In line with waste valorization, we explored the suitability of biochar produced from teff straw via pyrolysis, focusing on its prospects for agricultural applications. Teff straw-derived biochar (TSB) was obtained at 400, 500, and 600 °C and analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Fourier-transform infrared (FTIR) spectroscopy. The findings suggest that the pyrolysis temperature influences the surface microstructure and physicochemical properties of biochar. The optimum pyrolysis temperature (500 °C) was selected based on consideration of surface area change, ash content, energy consumption, biochar yield, and the intended target of application. The Brunauer–Emmett–Teller (BET) surface area of teff straw increased from 2.6 m 2 /g, with a maximum value of 18.4 m 2 /g at 500 °C, while temperatures below and above (400 and 600 °C), respectively, gave lower surface areas of 11.1 and 17.4 m 2 /g, respectively. At this temperature, the higher surface area, higher biochar yield, less energy consumption, and lower ash content were investigated compared with other pyrolysis temperature (600 °C). The findings of this study indicate that conversion of ETS to TSB at optimum temperatures of 500 °C would be better suited for use in agriculture and support a circular economy. Therefore, future studies should focus on real-world applications.