Effects Of Full Straw Retruning Combined With Nitrogen Fertilization On Paddy Soil Bacterial Gene Diversity And Greenhouse Gas Emission Flux

This study is based on field plot tests, we utilized research methods, such as PCR-DGGE, RT-PCR and static chamber-gas chromatography to investigate the effects of full rape straw returning combined with gradient nitrogen fertilizer on genetic diversity of soil bacteria, the abundance of amoA gene in ammonia-oxidizing Achaea, greenhouse gas emissions flux and the physical and chemical properties of the paddy soil. To explore appropriate straw returning measures,ecological conditions and greenhouse gas emissions reduction for local agricultural production, and provide theoretical and practical basis for perfecting the local straw returning technology, soil fertilization and ecological environment protection. The research results indicate that straw return significantly affected the bacterial diversity of paddy soil, the diversity index and richness index of SU treatments are higher than U treatments in Seedling stage, tillering stage and elongation stage, and it lower than U treatments in filling stage and maturation stage; With the increase of applied fertilizer, the diversity index and richness index of SU or U treatments showed different chang trends, and the evenness index has no significant changes. Specific strains appeared in different rice stages, these strains mainly attributable to Alphaproteobacteria, Actinobacteria, Methylomonadaceae, Nitrospira and Firmicutes. Straw returning combined with N fertilizer significantly increased amoA gene abundance in tillering stage, and the amoA gene abundance of straw returning with N fertilizer is significantly lower than the treatments of N fertilizer only.Treatments ?SU1-SU4? of straw returning with nitrogen fertilizer the highest carbon sequestration was 147.74 kg-hm^-2,38% more than only nitrogen fertilizer treatments ?U1-U4? on average. It suggested the straw-returning with nitrogen fertilizer could increase the soil carbon sequestration in contrast to the only nitrogen fertilizer treatments. Meanwhile, compared to the only nitrogen fertilizer treatment, straw returning with nitrogen fertilizer could reduce the N2O and CO2 emission, however, it increased CH4 emission slightly. The GHGI and GWPs of straw returning with nitrogen fertilizer, only nitrogen fertilizer and only straw returning were 0.372,5394.22 CO2-eq kg-hm^-2,0.630,9339.94 CO2-eq kg-hm^-2 and 0.816,9872.2 CO2-eq kg-hm^-2, respectively. It suggested the straw returning with nitrogen fertilizer could reduce GHGI emission and mitigate the global warming efficiently.