Stoichiometric ratio of dissolved organic carbon to nitrate regulates nitrous oxide emission from the biochar-amended soils

• Biochars can alter the biogeochemical properties and affect soil N2O emission.
• Effects of biochars of different feedstocks on soil N2O emission were studied.
• All biochars reduce N2O emission in Tenosol, but effect is inconsistent in Ferrosol.
• Biochar modifies stoichiometric ratio of DOC and NO3− and then affect N2O emission.