Responses of N2O production pathways and related functional microbes to temperature across greenhouse vegetable field soils

Abstract

Greenhouse vegetable field is one of the main sources of agricultural nitrous oxide (N2O) emissions via multiple pathways regulated by different microbes. However, the relative contributions of nitrifier nitrification, nitrifier denitrification, nitrification-coupled denitrification and heterotrophic denitrification to N2O production with temperature change in different greenhouse vegetable soils are poorly understood. In this study, combined approaches of the 15N–18O labeling technique and transcriptome analyses were applied to investigate the pathways of N2O production (nitrifier nitrification, nitrifier denitrification, nitrification-coupled denitrification and heterotrophic denitrification) under 15, 25 and 35 °C in six greenhouse vegetable field soils in mainland China. The results show that heterotrophic denitrification was an important source of N2O in acidic greenhouse vegetable soils, whereas nitrifier nitrification was the dominant source of N2O in alkaline greenhouse vegetable soils. In addition, the contribution of nitrifier denitrification and nitrification-coupled denitrification to N2O production in alkaline greenhouse vegetable soils were higher than in acidic greenhouse vegetable soils. The contribution of nitrification-coupled denitrification increased with temperature at 15–35 °C, whereas nitrifier denitrification increased with temperature at 15–25 °C. Overall, high temperature decreased the contribution of nitrifier nitrification to N2O production. These results have important implications for understanding the temperature-dependent N2O production pathways and for mitigating agricultural N2O emissions under different soil and temperature conditions.