A life cycle analysis (LCA) for pyrolysis biochar systems was carried out to determine greenhouse gas balance, carbon cycling, and the economics of biochar production from different agricultural residues and wastes. Investigating a range of feedstocks (forest residues, corn stover, etc.) provided insight into the use of biomass residues rather than bioenergy crops as biochar production substrates and the resulting energy and climate change impacts. The analyses were conducted based on various optimized pyrolysis parameters for corn fodder and forest residue. The observed reductions of greenhouse gas (GHG) emissions (CO2 equivalent per Mg dry feedstock) for both corn fodder and forest residue were mainly contributed by the stable carbon in the biochar. Corn fodder showed a greater reduction in emissions than forest residue, indicating the corn fodder’s greater economic potential for soil sequestration of stable carbon. The relative GHG emission analysis found that the optimization of a biomass pyrolysis system for biochar production is better suited for soil sequestration of stable carbon than as a fuel source. The economic viability of the pyrolysis-biochar system is largely dependent on the costs of feedstock production, pyrolysis, and the value of C offsets. The LCA reported in this study can be instrumental in assessing the environmental potential of biochar production and its application in the region.