> However, soil CO2 fluxes were suppressed when biochar was added to fertilized soils, indicating that biochar application is unlikely to stimulate CO2 fluxes in the agriculture sector, in which N fertilizer inputs are common.

> Our results showed that biochar application increased soil CO2 fluxes by 43.33% in unfertilized soils, but decreased by 8.61% in N-fertilized soils, consistent with the meta-analysis of Liu et al. (2016).

The metastudy did go into detail about N2O and CH4 as well in both fertilized and unfertilized soil.