Soil Bacterial Community and Greenhouse Gas Emissions as Responded to the Coupled Application of Nitrogen Fertilizer and Microbial Decomposing Inoculants in Wheat (Triticum aestivum L.) Seedling Stage under Different Water Regimes

Abstract

The soil microbial community is critically important in plant nutrition and health. However, this community is extremely sensitive to various environmental conditions. A pot experiment was conducted during the wheat seedling stage to better understand the influences of the coupled application of nitrogen (N) and microbial decomposing inoculants (MDI) on the soil bacteria community under different water regimes. There were two levels of water and six levels of fertilization. The results reveal that water stress increased the relative abundance of Acidobacteria and decreased that of Firmicutes and Proteobacteria. The application of 250 kg N ha−1 altered the diversity of the bacterial community but increased the relative abundance of nitrifying bacteria. Nitrous oxide (N2O) and carbon dioxide (CO2) emissions were negatively correlated with Myxococcota and Methylomirabilota while positively correlated with Patescibacteria. These two gases were also positively correlated with nitrifying bacteria, and the correlation was more significant under the full irrigation regime. These findings indicate that MDI does not substantially influence the soil bacterial community and its relationship with greenhouse gas emission at the wheat seedling stage and that the abundance of the soil bacterial community would mainly depend on the rational control of the amount of N and water applied.