Effects of biochar amendment on daily CO2 emission

<p>Poplar residue-derived biochars were larger in surface area and total pore volume but lower in nutrients and pH values than the rice straw-derived biochar. Increasing pyrolysis temperature led to a decrease in the total nitrogen content (TN) of poplar leaf- and rice straw-derived biochars, but enhanced the TN in the poplar twig- and poplar bark-derived biochars. After 180-day incubation, the total cumulative CO₂ emission decreased by 33.1–73.8% in the biochar amendments compared to their corresponding biomass residue addition, whereas the biochars derived from poplar twig and bark residues had more positive effects on reducing soil CO₂ emissions, but depended on the pyrolysis temperature.</p>