Substitution of organic and bio-organic fertilizers for mineral fertilizers to suppress nitrous oxide emissions from intensive vegetable fields

To gain insight into the microbial mechanisms associated with the replacement of chemical fertilizers with organic or bio-organic fertilizers to mitigate soil nitrous oxide (N2O) emissions, we measured N2O emissions from greenhouse vegetable soils through field observations and pot experiments. Results showed that organic substitution suppressed N2O emissions by reducing soil mineral N content and stimulating the abundance of the nosZII gene. The trade-off effect of bio-organic substitution on N2O emissions may be due to the stimulated activity of the AOA-amoA gene, resulting in unfavorable conditions for N2O production and thus reduced N2O loss. We also linked the inhibitory effect of organic and bio-organic substitution on N2O emissions to the increased abundance of key species in bacterial co-occurrence networks represented by Patescibacteria as they were significantly and negatively correlated with N2O emissions. However, the mitigation effect of bio-organic substitution on N2O emissions was conteracted by an increase in Bacillus abundance due to the direct negative effect of Bacillus on the nosZII gene abundance. These findings suggest that conventional or bio-organic substitution is a promising strategy for alleviating the environmental costs of crop production.