The mechanism of N2O production following chloropicrin (CP) fumigation was investigated in this study. Our results showed that CP fumigation increased N2O production from 23 to 25 times in comparison with the control and significantly decreased the abundance of 16S rRNA and N-cycling functional genes. CP also decreased the soil bacterial diversity and caused a shift in the community composition. The N2O emissions in fumigated soil were significantly correlated with soil environmental factors (NH4+, dissolved amino acid, microbial biomass nitrogen, and NO3-) but were not correlated with the abundance of functional genes. Metatranscriptomes and dual-label 15N-18O isotope analysis revealed that CP fumigation inhibited the expression of gene families involved in N2O production and sink processes and shifted the main pathway of N2O production from nitrification to denitrification. These results provided useful information for environmental safety assessments of CP in China, to improve our understanding of the N-cycling pathways in fumigated soils.
Keywords: N2O emissions; chloropicrin; functional genes; microorganisms; nitrogen cycling.