| CH4 is the second greenhouse gas, next to CO2. Flooded rice soil is an important source of atmospheric CH4. Heilongjiang province belongs to the cold rice region in northeast. The increased rice planting area produced huge amout of rice straw, and rice planting area reached 3.997 millon hectare in 2014. Straw returning can improve soil physical and chemical properties, soil organic matter, benefit the succeeding crops, and avoide the environmental pollution caused by str aw burning. So straw returning is a development direction for rice production in cold region. Straw returning affected CH4 emission and bacterial communities in rice soil. This experiment conducted with plot experiment and incubation experiment to study the effect of straw returning and temperature on CH4 emission, using static chamer method. Using the technology of high-throughput sequencing on Illumina platform to study the effect of straw returning on methanogens and methanotrophs. The results showed:Straw returning had a significant impact on dynamics of CH4 emission fluxes. The maximum CH4 emission fluxes of straw returning were observed in June 18 to June 28, the maximum CH4 emission fluxes of straw removal were observed in August 17 to August 27. The maximum and average CH4 emission fluxes increased with the increasing of straw returning amount. We carried out regression analyses for straw returning amount and CH4 emission fluxes, the fitted equations were y ?=0.0012x+5.886, R2=0.9795; y ?=0.0006x+1.3647, R2=0.9801.Rice straw returning only affacted CH4 emissions on current year. Total CH4 emission increased with the increasing of straw returning amount, the fitted equation was y=0.016x+37.874, R2=0.9767,total CH4 emission increased 16 kg·ha-2·y-1 with the straw returning amount increased 1000 kg·ha-2, the increased CH4 amount was 1.60% of the straw returning amount.Straw returning changed the correlation with air temperature and soil temperature. CH4 emission fluxes of straw removal were sigificant correlation with air temperature, and not siginificant with soil temperature. Methane emission fluxes of low amount and high amount straw returning were not significant correlation with air temperature, but highly significant correlation with the temperature of soil surface, 5 cm and 10 cm depth. The correlation coefficient was soil surface>5 cm depth>10 cm depth.Straw returning increased methangens relative abundance in rice soil. The methangens relative abundance of straw returning increased in the la te season, while the straw removal was decreased in the late season. Straw returning increased the abundance of acetoclastic methangens.The relative abundance of methanotrophs with straw returning was higher than straw removal. The relative abundance of methantrophs with straw returning increased in the late season, while the straw removal decreased. |
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