Resumen
Purpose Nitrogen (N) fertilizer application in agricultural soil is a primary anthropogenic nitrous oxide (N2O) source. Currently, the effect of the N fertilizer type on N2O emissions from upland soil has been rarely reported. To this end, impacts of various types of N fertilizer on N2O emissions in purple caitai (Brassica campestris L. ssp. chinensis var. purpurea) fields are investigated in this work. The field experiment was carried out with four treatments, including inorganic N fertilization (I), organic N fertilization (O), integrated organic-inorganic N fertilization (I+O) and no fertilization (CK). The nitrifier/denitrifier abundance was determined using absolute real-time quantitative PCR. Compared with I and O, I+O significantly increased dissolved organic C content, microbial biomass C and microbial biomass N by 24?63%, 12?38% and 13?36% on average, respectively. Moreover, the seasonal cumulative N2O-N emissions and fertilizer-induced N2O emission factor under I+O were significantly lower than those under I and O by 17?29% and 23?39%, respectively. The results indicate that N fertilizer type significantly affects the N2O emissions, and the integrated organic-inorganic N fertilization can mitigate the N2O emissions primarily by inhibiting the nitrification mediated by ammonia-oxidizing bacteria in purple caitai fields. Integrated organic-inorganic N fertilization is an ideal N fertilization regime to enhance soil fertility and yield and reduce N2O emissions in the upland fields.