BS in Materials Engineering
Materials Engineering Department
The soil additive properties of biochar have proven both effective and globally beneficial, but depend heavily on feedstock used and process conditions. This study characterizes how forced and natural draft air flows affect the biochar’s soil amendment potential. Biochars manufactured from two pine species of feedstock, in timber and pellet form, were compared against a designer biochar. The designer biochar held the lowest C:N ratio (57.43), followed by the natural draft pellets (199.5), forced air timber (282.5), forced air pellets (422.7), and natural draft timber (503.7). The designer char had the largest cation exchange capacity at 138.5 cmolc/kg; the decentralized biochars rated between 22.16 cmolc/kg and 62.33 cmolc/kg. X-ray diffraction failed to indicate the formation of turbostatic graphite, but confirmed the loss of organic content by the deflation of three broad cellulose peaks between 14.88-22.78°; expected mineralogical restructuring was confirmed in the designer biochar. Fourier-transform infrared spectroscopy confirmed the reduction in aliphatic functional groups (2820-2980 cm-1) and but failed to prove the formation of aromatic carbon-carbon double bonds (1580-1610 cm-1) after pyrolysis. Using scanning electron microscopy, draft conditions were concluded to have little or no effect on pore morphology. In order to help gauge the agricultural benefits of these biochars, an additional soil study is recommended to observe how soil interactions with the biochar affect the CEC and the C/N ratio over time.