Abstract
Biochar is a carbon-rich organic amendment often used to sequester carbon and sustain soil productivity. The characteristics and the potential benefits of biochars depend upon their feedstock type. Therefore, changes in stability and composition of biochars derived from different agricultural wastes viz. sugarcane filter cake (SF), farmyard manure (FM), and rice husk (RH) were investigated in this study. The feedstocks were pyrolyzed at 350 degrees C, and the resultant biochars (SF-BC, FM-BC, and RH-BC) were characterized for yield, proximate (moisture, volatile matter, fixed carbon, ash content) and ultimate (CEC & elemental composition) analyses, surface area (BET), surface morphology (SEM), structural and functional groups (FTIR), and thermal stability (TG-DTA). Results revealed that SF-BC exhibited the highest yield (42.18%), lower bulk density and particle density (0.131 g cm(-3) and 0.583 g cm(-3), respectively), and higher porosity (76.56%) while the FM-BC had highest contents of fixed carbon (46.83%). The pH was slightly neutral for SF-BC and RH-BC but alkaline for FM-BC. The electrical conductivity and TDS were considerably higher in FM-BC while the CEC was higher in RH-BC (28.24 cmol kg(-1)). The recalcitrance index (R-50) showed that all the biochars were minimally degradable (0.7 > R-50 >= 0.5). The SF-BC exhibited highest stability with R-50 value of 0.64 and also showed highest C sequestration potential (43.68%). Hence, it is concluded that thermal conversion of sugarcane filter cake waste into biochar might serve as a potential candidate to increase soil organic C pool if applied as soil amendment.