Mechanism Of Responding Microbial And The Capacity Of N₂O Consumption In Paddy Soil

Nitrous oxide(N2O)is a potent greenhouse gas,who's global warming potential is 320 times that of CO2.Paddy soil is the most important source of N2O and important N2O sink.Typical denitrifying bacteria(nosZ-?)and atypical denitrifying bacteria(nosZ-?)are the only biological pathways to catalyze N2O uptake in soil,though the capacity of N2O consumption and the response mechanism of related functional microorganisms in paddy fields is not yet clear.We collected intact soil cores of typical flooding paddy fields with different soil parent materials that derived from lateritic soil,river alluvium and quaternary red soil.Exogenous N2O gas was input through the bottom of flooding paddy soil cores in laboratory.The dynamic of N2O and N2 concentration and key soil factors were systematically monitored.Meanwhile,the community composition and structure of nosZ-? and nosZ-?-containing population were investigated by high-throughput sequencing approaches,with the purpose of revealing the N2O uptake ability and the response mechanism of nosZ-? and nosZ-?-containing population of flooded paddy soils.This study has important guiding significance in improving soil nitrogen utilization efficiency and reducing soil N2O emission in rice field.The main research results are as follows:(1)The addition of exogenous N2O significantly promoted the rate of N2O uptake and increased N2 emissions of paddy soils.Absorption capacity of N2O in different flooded paddy soil column was as follows:lateritic soil? river alluvium?quaternary red soil,and which is stronger in the 0-5 cm soil layer.(2)The addition of exogenous N2O significantly promoted the consumption of NH4+-N,NO3--N,and DOC in flooded paddy soils.The consumption capacity of NH4+-N was stronger in the 5-10 cm soil layer,and which was as follows:laterite soil ?river alluvium ?quaternary red soil;The consumption capacity of NO3--N and DOC was stronger in the 0-5 cm soil layer,and that was as follows:laterite soil? river alluvium? quaternary red soil.(3)While the diversity of nosZ-? and nosZ-?-containing community had no significant change after the addition of N2O,which has significant difference between different paddy soils,and the diversity of nosZ-? and nosZ-?-containing community was weaker in the soil layer of 0-5 cm than that of 5-10 cm.Meantime the diversity of nosZ-?-containing community was higher than that of nosZ-?-containing community in the individual sample,indicating that nosZ-II-containing community has potential N2O absorption capacity.(4)The community composition of nosZ-? and nosZ-?-containing bacteria had significant difference in the three types of rice soil.The N2O reduction process of soil was mainly effected the community composition and relative abundance of each nitrous oxide reducing bacterial on OTU level of different paddy soil.Compared with nosZ-?-containing community,the relative abundance of nosZ-?-containing dominant community was higher in each paddy soil;The relative abundance of nosZ-?-containing dominant community and a few non-dominant community(OTU level)had significant changes in each paddy soil after adding exogenous N2O,and which was as follows:laterite? river alluvium? quaternary red soil.However the relative abundance of nosZ-?-containing superiority community(OTU level)had slight changes between different types paddy soils,and that was as follows:the river alluvium? quaternary red soil? laterite.On the whole,compared with 5-10 cm,the relative abundance of nosZ-?-containing dominant community(OTU level)varied significantly from 0-5 cm depth.In addtion,the relative abundance of nosZ-?-containing dominant community(OTU level)varied significantly from 5-10 cm.