Characteristics Of Greenhouse Gas Emission From Paddy Fields During Fallow Period And Its Influencing Factors

China is a big agricultural country,agricultural production plays an important role in China,and the environmental effects brought by agricultural production can not be ignored.In order to improve the sustainable development of agricultural production and fill the gap of unknown environmental effects in farmland ecosystem,this experiment was designed to study the greenhouse gas emissions of typical red soil paddy fields in southern China during the fallow period.The field experiment was carried out in Taoyuan agroecological experimental station of Chinese Academy of Sciences,and the indoor cultivation experiment was carried out in paddy red soil during leisure period.In which the soil was divided into three fertilization treatments:（1）CK treatment.（2）NPK treatment.（3）NPKC treatment.Two kinds of water changes were set simultaneously in the indoor culture experiment:（1）40%moisture content of soil in simulated leisure period;（2）100%water content in soil flooding state during the simulation growth period.Two kinds of straw changes were set:（1）Straw was added,and ¹³C marker was added to the straw;（2）Straw was not added.One was temperature condition:constant temperature 25℃.The results of field experiment show that:（1）The long-term input of carbon and nitrogen will make soil organic carbon and total nitrogen reach saturation,resulting in the loss of excess carbon and nitrogen from paddy fields in different forms,and greenhouse gas emission is one of the main ways.Fallow period is an important period of N₂O emission,which accounts for more than 64%of the annual emission.No matter in the fallow period or growth period,the N₂O emission was significantly increased by returning organic matter to the field（P<0.05）.The results of laboratory culture experiment show that:（1）Under the condition of submerged water:N₂O is discharged in large quantities,and its discharge accounts for 28.65%of the total discharge.The average emission of CO₂ is 28.0%.（2）It can be obtained by ¹³C mark,the main discharge of CO₂ is not flooded,but CH₄ is less;CH₄ emission increases when flooding,and CO₂ and CH₄ are higher.（3）Under different water conditions,the straw addition increased the comprehensive potential of temperature increase（P<0.05）,and the average increase of temperature potential was 267.4%and 1517.5%under the two water conditions.Under different straw addition conditions,the potential of comprehensive temperature increase was significantly increased by flooding（P<0.05）,which mainly showed that it promoted the production and release of CH₄,and the average increase of the potential of temperature increase of no straw and straw increased by 712.5%and 1363.6%.（4）According to the correlation analysis,the straw addition and CH₄ emission were significantly positive correlation（P<0.05）,and the CO₂ emission was significantly positive correlation（P<0.01）;the straw addition and CH₄ emission were significantly negative correlation（P<0.01）,and the CO₂ emission was significantly positive（P<0.01）,and the N₂O emission was significantly positive（P<0.05）.The straw addition significantly affected the emission of greenhouse gases.（5）When the water is not flooded,the microbial biomass carbon and nitrogen content significantly affect the emission of three greenhouse gases,the NH₄⁺-N content significantly affects the emissions of CH₄ and CO₂;the NH₄⁺-N significantly affects the emissions of three greenhouse gases in flooding.