【Objective】Ammonia oxidizers make an important contribution to N₂O emissions. However, the composition of their relative contribution to N₂O emission in different soils and agricultural management systems has not been systematically studied.【Method】We studied the contributions of AOB, AOA + comammox and heterotrophic nitrifiers to the potential nitrification rate, net nitrification rate and N₂O emission in typical upland surface soils (fluvo-aquic soil, black soil, latosol, red soil), and in latosols from soil profile under organic fertilizer amendment.【Result】In the surface fluvo-aquic soil, black soil, latosol and red soil, potential nitrification rate significantly increased with soil pH (P < 0.05), and was 32.5, 6.6, 4.8 and 2.3 mg·kg^-1·d^-1, respectively. AOB dominated the potential nitrification rate in the above surface soils, with contributions ranging 58%-100%. Further analyses of the fluvo-aquic soil, black soil and latosol indicated that net nitrification rate and N₂O emission both significantly increased with soil pH (P < 0.05), which were consistent with potential nitrification rate. For the net nitrification rate, AOB and AOA + comammox contributed equally (30%-40%) in the fluvo-aquic soil and latosol, while AOB dominated in the black soil (72%). N₂O emissions from the fluvo-aquic soil, black soil and latosol were all dominated by AOB (58%-92%). For soils from the organic fertilizer-amended latosol profile, pH, potential nitrification rate, net nitrification rate and N₂O emission significantly increased from the subsurface to surface layer (P < 0.05). The increase in potential nitrification rate and net nitrification rate was dominated by AOA + comammox (contributing 63% and 54%) and the increase in N₂O emission was dominated by AOB (contributing 54%).【Conclusion】This study provides new evidence for developing reduction measures of N₂O emissions that match the soil ammonia oxidation characteristics and soil properties.