Effect Of Different Moisture Content On N₂O Consumption Potential Of Paddy Soil And NosZ-containing Microbial Community

N₂O is the third major greenhouse gas（GHG）after carbon dioxide（CO₂）and methane（CH4）.N₂O has 298-fold higher warming potential than CO₂.And paddy soil is one of the most important agricultural soil types in China,accounting for 27% of the country’s total arable land area.It is not only a strong N₂O source,but also a N₂O sink.The contribution of N₂O consumption to the reduction in net N₂O emission from paddy soil varies with moisture content.However,little is known about the effects of different moisture contents on N₂O consumption process of paddy soil and key microbial communities’ regulatory mechanisms.Typical paddy soils in Hubei Province were selected for the experiment.We designed and conducted a microcosm experiment controlled for mass moisture content（20%,35%,50%,and 70%gravitated moisture content）and applied exogenous N₂O to the paddy soil.At the same time,the change characteristics of nos Z-containing microbial community structure,and its internal relationship with N₂O consumption were analyzed.This study provides more ideas for N₂O reduction in paddy soil under different moisture conditions and provides an important reference for the mitigation of N₂O emission in paddy fields.The main conclusions of this paper are as follows:（1）The total N₂O consumption and consumption rate of paddy soil increased with moisture content,35%,50%,and 70% moisture content were significantly higher than 20%,and maximum consumption rate was 200.17 μg·（m2·h）-1 under 70% moisture content.（2）N₂O consumption of paddy soil with different moisture content was positively correlated with NO₃^--N,DOC consumption,and p H,while the NH₄⁺-N consumption was negatively correlated（p<0.05）.The dominant factor of N₂O consumption in paddy soil with 20%and 35% moisture content was NH₄⁺-N consumption.However,NO₃^--N,DOC consumption and p H were the dominant factors of N₂O consumption in paddy soil with 50% and 70%moisture content.（3）The addition of exogenous N₂O gas did not affect the richness of nos Z-containing denitrifying microorganisms with 20%,35% and 50% moisture content.There were significant differences in nos Z-containing microbial community diversity between low moisture content（20% and 35%）and high moisture content（50% and 70%）,and the diversity and richness of species increased with the moisture content.Soil moisture content regulated the denitrification rate mainly by influencing the composition and relative abundance of nos Z-containing denitrifying microbial community,and then affected the consumption of N₂O.In the phylogenetic classification of phyla,Proteobacteria increased with the moisture content and was significantly positively correlated with N₂O consumption（p<0.05）.In phylogenetic classification of family,the dominant bacteria families are Oxalobacteraceae,Comamonadaceae,Zoogloeaceae,Bradyrhizobiaceae,Rhodospirillaceae,Methylobacteriaceae,and Chelatococcaceae.Among them,Oxalobacteraceae and Zoogloeaceae were significantly positively correlated with N₂O consumption（p<0.05）.（4）For common OTUs,99.18% of the variation in nos Z-containing microbial community structure could be explained by measured factors.Among them,NO₃^--N,NH₄⁺-N consumption,and p H were the dominant factors.For unique OTUs under different moisture content,the unique microbial community was positively correlated with NH₄⁺-N consumption in paddy soil under 20% moisture content,and the unique microbial community was positively correlated with p H and NO₃^--N consumption under 70% moisture content.