Appropriate Irrigation and Fertilization Regime Restrain Indigenous Soil Key Ammonia-Oxidizing Archaeal and Bacterial Consortia to Mitigate Greenhouse Gas Emissions

Abstract

Harnessing an ammonia-oxidizing microbiome has become an increasingly attractive form of management for mitigating greenhouse gas emissions in rice paddies; however, the relationship between greenhouse gas emissions and ammonia-oxidizing microbiomes, using a nitrogen application and irrigation regime, has not been well investigated. To decipher which of (and how) the specific mmonia-oxidizing bacterial species drive the greenhouse gas CH4 and N2O emissions, a field experiment with varying nitrogen application and irrigation regimes was initiated to investigate the succession of key bacterial consortia associated with GHG emissions. The results showed that water-saving irrigation (AWD) significantly increased NO3-N and NH4+-N concentrations, compared with conventional irrigation (FDF), whereas (total nitrogen) TN was little higher in FDF (1.38 g kg−1) compared with the AWD (1.36 g kg−1). During the rice-growing season, CH4 emissions ascended speedily, and emissions peaked at maximum values of 3.32 and 4.41 ug mg−2 h−1 on day 5 in FDF and AWD irrigation regimes, respectively, and then they rapidly decreased during the midseason period, maintaining a relatively low emission rate until the rice was harvested. The patterns of N2O emission fluxes had the same tendencies with N fertilization. Putative key taxa, such as Flavobacterium, Massilia, Arenimonas, Novosphingobium, Pseudomonas, exhibited significant positive relationships with higher GHG emissions, suggesting that they make particularly obvious contributions to N2O emissions. These putative taxa should be considered when designing a high nitrogen application and irrigation strategy. As such, the nitrogen application of N180, and the irrigation regimes of water-saving irrigation, are recommended methods for N conservation and the mitigation of greenhouse gas emissions in rice paddies.