Relative Contribution of Ammonia-oxidizing Microorganisms to Nitrous Oxide Emissions in Upland Agricultural Soils
[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.
国家科技期刊平台
NSTL
万方数据
