| Based on Arc GIS software and Denitrification-Decomposition（DNDC）model,this paper analyzed the dynamic characteristics and influencing factors of soil organic carbon in Huainan farmland from 1980 to 2021.Firstly,the GIS database and meteorological database required for model operation were established by superimposing land use type map and soil type map.Secondly,the accuracy of the model was verified by comparing with the measured data,in order to simulate the changes of soil organic carbon and carbon sequestration potential in Huainan City.The correlation between soil organic carbon content and p H,soil bulk density,soil cation exchange capacity and clay content was analyzed,and the influence mechanism of these factors on soil organic carbon content was discussed.Then,the differences of soil organic carbon content under different rotation systems were compared and analyzed.Finally,using the different emission scenarios proposed by the United Nations Intergovernmental Panel on Climate Change（IPCC）,the low emission scenario（RCP2.6）and the medium emission scenario（RCP6.0）were selected as the future scenarios to simulate the characteristics of soil organic carbon and greenhouse gas emissions in Huainan City in the next 40 years.The main conclusions are as follows:（1）Organic carbon in farmland soil（0-20cm）in Huainan City increased from159.01×105 t C in 1980 increased to 2.48×107 t C in 2021,with a growth rate of 55.97%and an average annual growth rate of 1.33%,can increase organic carbon by 2.07 t per year.The highest soil organic carbon content in Tianjia’an District is 18.71 g·kg-1,and Shouxian County has the largest organic carbon storage.In 2021,the organic carbon content reached 1.53×107 t C,the change rate of soil organic carbon density in Fengtai County was the largest,reaching 105.22%,while the lowest increase rate was 35.99%in Datong District.The organic carbon content of farmland soil in Huainan is negatively correlated with gravel volume content,sand content,p H,and soil bulk density,while positively correlated with silt content,soil cation exchange capacity,and clay content.（2）Among the six simulation scenarios set up by,Huainan City generally has organic carbon storage under different simulation scenarios:no-tillage+chemical fertilizer combined with organic fertilizer+straw returning 90%（MFO）>less tillage+chemical fertilizer combined with organic fertilizer+straw returning 90%（SFO）>traditional tillage+chemical fertilizer combined with organic fertilizer+straw returning 90%（TFO）>traditional tillage+single application of chemical fertilizer+straw returning 90%（TFH）>traditional tillage+single application of organic fertilizer+straw returning 90%（TOH）>traditional tillage+single application of chemical fertilizer+straw not returning（TFN）.The increase rate of soil organic carbon in Huainan City under SFO and MFO treatments was higher than that under other management modes.Under the current farmland management mode,the soil organic carbon potential in Huainan was 6.34×108 t C,and the carbon sequestration potential was TFO>MFO>SFO>TFH>TOH>TFN.The organic carbon content of maize-soybean,rice-wheat and cotton-rape rotation systems was higher,and the soil organic carbon content of maize-soybean rotation system was the highest,which could increase organic carbon by 0.42 g·kg-1 per year on average.（3）Compared with conventional climate’Huainan’s SOC storage increased under both RCP2.6 and RCP6.0 emission scenarios.Under RCP2.6 climate mode,average annual SOC increased by 4.44×105 t C,under RCP6.0 scenario,average annual SOC increased by 4.88×105 t C.In 2060,RCP2.6 and RCP6.0 CH4 emissions were higher than conventional climate by 0.29 t C·hm-2 and 0.96 t C·hm-2 respectively.N2O emissions were lower than CH4,RCP2.6 and RCP6.0 N2O emissions were higher than conventional climate by135.62 kg N·hm-2 and 213.76 kg N·hm-2 respectively.Figure[32]table[7]reference[144]... |
