The GHG emissions caused by N fertilizer applied to croplands are mainly in the form of N2O, including direct and indirect emissions. We classified Chinese agricultural land into two groups: upland fields and paddy fields. We compiled all published field measurements in China (a total of 853) and summarized the results using a meta-analysis method to derive direct and indirect N2O emission factors. Direct emission factors for upland fields and paddy fields were obtained from a study by Gao et al. (38), which includes 456 N2O emission measurements in China (195 paddy fields and 261 upland fields). Indirect emissions include N2O resulting from N deposition (associated with NH3 volatilization)