Spatial-temporal Variation of Methane Emissions from Rice Fields and Influencing Factors in Liaoning Province

Rice fields are main source of methane（CH₄）emissions, accuracy of DNDC model was verified by eddy covariance, and then DNDC model was used to simulate methane emissions of Liaoning Province from 2016 to 2020．Results suggested that there was a good agreement between DNDC model and eddy covariance（P<0.001）．Average annual methane emission was 71 000 tons and mainly distributed in Shenyang City and Panjin City．Methane emission rate increased with temperature, soil organic carbon and soil bulk density．However, there was a threshold value for influence of precipitation on methane emission rate．When accumulated precipitation in June and July was from 158 mm to 317 mm, methane emission rate had a positive correlation with precipitation．Otherwise there was an negative correlation between methane emission rate and precipitation．Within threshold, precipitation changed soil enviroment and directly affected methane emission rate, but when precipitation was too much or too little, it indirectly affected methane emission rate through temperature．Maximum lengthening sun-drying time was an effective operation to reduce methane emission．Research results could provide theoretical support for assessment, prediction and control measures of methane emission of rice fields in Liaoning Province．