Characteristics And Influencing Factors Of Greenhouse Gas Emissions From Yellow Soil Paddy Fields Replaced By Organic Fertilizer For 26 Year

In order to clarify the characteristics of greenhouse gas emissions from long-term organic fertilizer replacement in the yellow soil paddy field in central Guizhou and its relationship with environmental factors,the study was based the long-term fertilization experiment of yellow soil fertility and fertilizer efficiency in Scientific Observing and Experimental Station of Arable Land Conservation and Agricultural Environment（Guizhou）,Ministry of Agriculture,four treatments including balanced application of chemical fertilizer（NPK）,100%organic fertilizer nitrogen instead of chemical fertilizer nitrogen（100%ON）,50%organic fertilizer nitrogen instead of chemical fertilizer nitrogen（50%ON）,and 25%organic fertilizer nitrogen instead of chemical fertilizer nitrogen（25%ON）were selected,static closed chamber and gas chromatography was used to monitor the CH₄,CO₂and N₂O emissions of paddy fields during the growth period and idle period after 26 years of continuous fertilization,in order to explore the characteristics of greenhouse gas emissions from yellow soil rice fields under the influence of different long-term fertilization treatments.Soil samples were collected during the growth stages of rice（seedling stage,tillering stage,jointing stage,heading stage,and maturity stage）,determination of soil microbial biomass carbon（SMBC）,microbial biomass nitrogen（SMBN）,ammonium nitrogen（NH₄⁺-N）,nitrate nitrogen（NO₃^--N）,total dissolved nitrogen（TDN）and labile organic carbon（LOC）content,in order to clarify the long-term effects of different proportions of organic fertilizer replacement on soil-related carbon and nitrogen nutrients,and then combined with correlation analysis and path analysis to comprehensively explore the relationship between greenhouse gas emission characteristics and environmental factors.Draw the following conclusions:（1）The variation range of CH₄emission flux was:-0.10 mg·m^-2·h^-1-15.90 mg·m^-2·h^-1;organic fertilizer application increased CH₄emission,and the emission increased with the increase of organic fertilizer replacement ratio,compared with NPK treatment,the total CH₄emissions were increased by 357.75%,156.13%and 42.80%when the replacement ratio was100%,50%and 25%,respectively.The variation range of CO₂emission flux was:6.71mg·m^-2·h^-1-1866.18 mg·m^-2·h^-1;the total CO₂emission was in descending order:100%ON>25%ON>NPK>50%ON,compared with NPK treatment,100%ON was significantly increased by 31.60%,and there was no significant difference among other treatments.The variation range of N₂O emission flux was:-21.24 ug·m^-2·h^-1-61.73 ug·m^-2·h^-1;the total N₂O emission was in descending order:25%ON>50%ON>NPK>100%ON,compared with NPK,100%ON treatment significantly decreased by 32.16%,and there was no significant difference among other treatments.Both the warming potential and emission intensity were as follows:100%organic substitution>50%organic substitution>25%organic substitution>balanced application of chemical fertilizers.Compared with balanced application of chemical fertilizers,the warming potential and emission intensity of 100%organic substitution were significantly increased.292.82%and 306.25%,50%organic substitution increased significantly by 131.20%and 131.25%,25%organic substitution increased by 38.31%and50.00%,but the difference was not significant.（2）The application of organic fertilizer increased the soil organic carbon content,and the treatment of organic substitution significantly increased by 47.06%-79.98%compared with the balanced application of chemical fertilizer.The contents of SMBC and LOC in each organic replacement treatment were higher than those in the NPK treatment,and the higher the organic fertilizer application rate,the higher the content.The content of SMBC was higher at the seedling,jointing and maturity stages,and decreased at the tillering and heading stages,while the LOC content fluctuated less during the whole growth period.After the tillering stage,the content of SMBN in the organic replacement treatment was higher than that in the NPK treatment,and the content of SMBN in the tillering and jointing stages was higher.The content of NH₄⁺-N in the three treatments of organic substitution in tillering stage was significantly higher than that in the treatment with balanced application of chemical fertilizer,the difference was not significant in other stages,and the NH₄⁺-N content in the whole growth period showed a decreasing trend.The NO₃^--N content fluctuated less before heading stage,and the NO₃^--N content increased significantly at the maturity stage,and there was no significant difference in NO₃^--N content among the treatments.The content of TDN gradually decreased with the progress of the growth process,and was the highest at the seedling stage,and decreased to the lowest at the heading and maturity stages.（3）Compared with the balanced application of chemical fertilizers,the net global warming potential decreased by 18.50%,27.00%and 71.10%when the organic fertilizer replacement ratio was 100%,50%and 25%,respectively,and the differences among treatments were significant except for 100%organic replacement.There was a very significant positive correlation between CH₄emission flux and LOC,SMBN,soil water content,0-5 cm soil temperature,5-10 cm soil temperature,air temperature（P<0.01）,but a very significant negative correlation with NO₃^--N relationship.There was a very significant positive correlation between CO₂emission flux and air temperature,a significant positive correlation between soil water content,0-5 cm soil temperature,5-10 cm soil temperature,and precipitation（P<0.05）,and a significant negative correlation with SMBC,a very significant negative correlation between NO₃^--N and TDN.The N₂O emission flux has a very significant positive correlation with the NO₃^--N content,and has a very significant negative correlation with NH₄⁺-N,soil water content,0-5 cm soil temperature,5-10 cm soil temperature,and air temperature,and has a significant negative correlation with LOC and SMBN.SMBC,LOC,SMBN,NH₄⁺-N content,TDN,0-5 cm soil temperature,5-10 cm soil temperature,precipitation,organic carbon input directly affect greenhouse gas emissions.